crypto

v5.8.3

crypto

Crypto Functions

This module provides a set of cryptographic functions.

Hash functions -

SHA1, SHA2 - Secure Hash Standard (FIPS PUB180-4)

SHA3 - SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions (FIPS PUB 202)

BLAKE2 - BLAKE2 — fast secure hashing

SM3 - The SM3 Hash Function (GM/T 0004-2012)

MD5 - The MD5 Message Digest Algorithm (RFC 1321)

MD4 - The MD4 Message Digest Algorithm (RFC 1320)

MACs - Message Authentication Codes -

Hmac functions - Keyed-Hashing for Message Authentication (RFC 2104)

Cmac functions - The AES-CMAC Algorithm (RFC 4493)

POLY1305 - ChaCha20 and Poly1305 for IETF Protocols (RFC 7539)

Symmetric Ciphers -

DES, 3DES and AES - Block Cipher Techniques (NIST)

Blowfish - Fast Software Encryption, Cambridge Security Workshop Proceedings (December 1993), Springer-Verlag, 1994, pp. 191-204.

Chacha20 - ChaCha20 and Poly1305 for IETF Protocols (RFC 7539)

Chacha20_poly1305 - ChaCha20 and Poly1305 for IETF Protocols (RFC 7539)

SM4 - The SM4 Block Cipher Algorithm

Modes -

ECB, CBC, CFB, OFB and CTR - Recommendation for Block Cipher Modes of Operation: Methods and Techniques (NIST SP 800-38A)

GCM - Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC (NIST SP 800-38D)

CCM - Recommendation for Block Cipher Modes of Operation: The CCM Mode for Authentication and Confidentiality (NIST SP 800-38C)

Asymmetric Ciphers - Public Key Techniques -

RSA - PKCS #1: RSA Cryptography Specifications (RFC 3447)

DSS - Digital Signature Standard (DSS) (FIPS 186-4)

ECDSA - Elliptic Curve Digital Signature Algorithm (ECDSA)

SRP - The SRP Authentication and Key Exchange System (RFC 2945)

Note

The actual supported algorithms and features depends on their availability in the actual libcrypto used. See the crypto (App) about dependencies.

Enabling FIPS mode will also disable algorithms and features.

The CRYPTO User's Guide has more information on FIPS, Engines and Algorithm Details like key lengths.

Exceptions

Atoms - the older style

The exception error:badarg signifies that one or more arguments are of wrong data type, or are otherwise badly formed.

The exception error:notsup signifies that the algorithm is known but is not supported by current underlying libcrypto or explicitly disabled when building that.

For a list of supported algorithms, see supports(ciphers).

3-tuples - the new style

The exception is:

error:{Tag, C_FileInfo, Description}

Tag = badarg | notsup | error
C_FileInfo = term()    % Usually only useful for the OTP maintainer
Description = string() % Clear text, sometimes only useful for the OTP maintainer

The exception tags are:

badarg - Signifies that one or more arguments are of wrong data type or are otherwise badly formed.

notsup - Signifies that the algorithm is known but is not supported by current underlying libcrypto or explicitly disabled when building that one.

error - An error condition that should not occur, for example a memory allocation failed or the underlying cryptolib returned an error code, for example "Can't initialize context, step 1". Those text usually needs searching the C-code to be understood.

Usually there are more information in the call stack about which argument caused the exception and what the values where.

To catch the exception, use for example:

try crypto:crypto_init(Ciph, Key, IV, true)
    catch
        error:{Tag, _C_FileInfo, Description} ->
            do_something(......)
         .....
end

Summary

Types: Ciphers

cipher()

cipher_aead()

Ciphers known by the CRYPTO application.

cipher_iv()

cipher_no_iv()

crypto_opt()

Selects encryption ({encrypt,true}) or decryption ({encrypt,false}).

crypto_opts()

Equivalent to crypto_opt().

cryptolib_padding()

The cryptolib_padding are paddings that may be present in the underlying cryptolib linked to the Erlang/OTP crypto app.

otp_padding()

Erlang/OTP adds a either padding of zeroes or padding with random bytes.

padding()

This option handles padding in the last block. If not set, no padding is done and any bytes in the last unfilled block is silently discarded.

Types: Diffie-Hellman Keys and parameters

dh_params()

dh_private()

dh_public()

Equivalent to dh_private().

ecdh_params()

ecdh_private()

Equivalent to ecdh_params().

ecdh_public()

Equivalent to ecdh_params().

Types: Digests and hash

blake2()

cmac_cipher_algorithm()

compatibility_only_hash()

The compatibility_only_hash/0 algorithms are recommended only for compatibility with existing applications.

dss_digest_type()

ecdsa_digest_type()

hash_algorithm()

hash_xof_algorithm()

hmac_hash_algorithm()

rsa_digest_type()

sha1()

Equivalent to blake2().

sha2()

Equivalent to blake2().

sha3()

Equivalent to blake2().

sha3_xof()

Equivalent to blake2().

Types: Elliptic Curves

ec_basis()

Curve definition details.

ec_characteristic_two_field()

Equivalent to ec_basis().

ec_curve()

Parametric curve definition.

ec_explicit_curve()

Equivalent to ec_curve().

ec_field()

Equivalent to ec_curve().

ec_named_curve()

Equivalent to edwards_curve_ed().

ec_prime_field()

Equivalent to ec_basis().

edwards_curve_dh()

Equivalent to edwards_curve_ed().

edwards_curve_ed()

Note that some curves are disabled if FIPS is enabled.

Types: Internal data types

crypto_state()

Equivalent to mac_state().

hash_state()

Equivalent to mac_state().

mac_state()

Contexts with an internal state that should not be manipulated but passed between function calls.

Types: Key Encapsulation Mechanism

kem()

Key encapsulation mechanisms.

Types: Keys

key_integer()

Always binary/0 when used as return value

Types: Public Key Ciphers

pk_encrypt_decrypt_algs()

Algorithms for public key encrypt/decrypt. Only RSA is supported.

pk_encrypt_decrypt_opts()

Equivalent to rsa_padding().

rsa_compat_opts()

Those option forms are kept only for compatibility and should not be used in new code.

rsa_opt()

Equivalent to rsa_padding().

rsa_padding()

Options for public key encrypt/decrypt. Only RSA is supported.

Types: Public Key Sign and Verify

pk_sign_verify_algs()

Algorithms for sign and verify.

pk_sign_verify_opts()

Equivalent to rsa_sign_verify_padding().

rsa_sign_verify_opt()

Equivalent to rsa_sign_verify_padding().

rsa_sign_verify_padding()

Options for sign and verify.

Types: Public/Private Keys

dss_private()

dss_public()

Equivalent to dss_private().

ecdsa_params()

ecdsa_private()

Equivalent to ecdsa_params().

ecdsa_public()

Equivalent to ecdsa_params().

eddsa_params()

eddsa_private()

Equivalent to eddsa_params().

eddsa_public()

Equivalent to eddsa_params().

rsa_params()

rsa_private()

Equivalent to rsa_params().

rsa_public()

Equivalent to rsa_params().

srp_comp_params()

Equivalent to srp_host_comp_params().

srp_gen_params()

Equivalent to srp_host_comp_params().

srp_host_comp_params()

Where Verifier is v, Generator is g and Prime isN, DerivedKey is X, and Scrambler is u (optional will be generated if not provided) from SRP design Version = '3' | '6' | '6a'

srp_host_gen_params()

Equivalent to srp_host_comp_params().

srp_private()

srp_public()

Equivalent to srp_private().

srp_user_comp_params()

Equivalent to srp_host_comp_params().

srp_user_gen_params()

Equivalent to srp_host_comp_params().

Types: Types for Engines

engine_cmnd()

Pre and Post commands for engine_load/3 and /4.

engine_key_ref()

Equivalent to engine_ref().

engine_method_type()

engine_ref()

The result of a call to engine_load/3.

key_id()

Identifies the key to be used. The format depends on the loaded engine. It is passed to the ENGINE_load_(private|public)_key functions in libcrypto.

password()

The password of the key stored in an engine.

Types

crypto_integer()

mldsa()

mldsa_private()

mldsa_public()

rand_cache_state()

rand_plugin_aes_state()

rand_plugin_prng1_init_state()

rand_plugin_prng1_state()

rand_plugin_state()

slh_dsa()

slh_dsa_private()

slh_dsa_public()

Cipher API

crypto_final(State)

Finalize a streaming encryptions or decryptions operation and delivers the final bytes of the final block.

crypto_get_data(State)

Return information about a crypto_state/0.

crypto_init(Cipher, Key, FlagOrOptions)

Initialize the state for a streaming encryption or decryption operation.

crypto_init(Cipher, Key, IV, FlagOrOptions)

Initialize the state for a streaming encryptions or decryptions operation.

crypto_one_time(Cipher, Key, Data, FlagOrOptions)

Do a complete encrypt or decrypt of the full text.

crypto_one_time(Cipher, Key, IV, Data, FlagOrOptions)

Do a complete encrypt or decrypt of the full text.

crypto_one_time_aead(State, IV, InText, AAD)

Do a complete encrypt or decrypt with an AEAD cipher of the full text.

crypto_one_time_aead(Cipher, Key, IV, InText, AAD, EncFlag)

Do a complete encrypt with an AEAD cipher of the full text with the default tag length.

crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagOrTagLength, EncFlag)

Do a complete encrypt or decrypt with an AEAD cipher of the full text.

crypto_one_time_aead_init(Cipher, Key, TagLength, EncFlag)

Initializes AEAD cipher.

crypto_update(State, Data)

Add data to a streaming encryption or decryption operation.

Deprecated API

enable_fips_mode(Enable) deprecated

Enable or disable FIPs mode.

start() deprecated

Use application:start(crypto) instead.

stop() deprecated

Use application:stop(crypto) instead.

Engine API

engine_add(Engine)

Add the engine to OpenSSL's internal list.

engine_by_id(EngineId)

Get a reference to an already loaded engine with EngineId. An error tuple is returned if the engine cannot be unloaded.

engine_ctrl_cmd_string(Engine, CmdName, CmdArg)

Send ctrl commands to an OpenSSL engine.

engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional)

Send ctrl commands to an OpenSSL engine.

engine_get_all_methods()

Return a list of all possible engine methods.

engine_get_id(Engine)

Return the ID for the engine, or an empty binary if there is no id set.

engine_get_name(Engine)

Return the name (eg a description) for the engine, or an empty binary if there is no name set.

engine_list()

List the id's of all engines in OpenSSL's internal list.

engine_load(EngineId, PreCmds, PostCmds)

Load an OpenSSL engine.

engine_register(Engine, EngineMethods)

Register engine to handle some type of methods, for example engine_method_digests.

engine_remove(Engine)

Remove the engine from OpenSSL's internal list.

engine_unload(Engine)

Unload an OpenSSL engine.

engine_unregister(Engine, EngineMethods)

Unregister engine so it does not handle some type of methods.

ensure_engine_loaded(EngineId, LibPath)

Load a dynamic engine if not already done.

pbkdf2_hmac(Digest, Pass, Salt, Iter, KeyLen)

PKCS #5 PBKDF2 (Password-Based Key Derivation Function 2) in combination with HMAC.

privkey_to_pubkey(Type, EnginePrivateKeyRef)

Fetch public key from a private key stored in an Engine.

Hash API

hash(Type, Data)

Compute a message digest.

hash_final(State)

Finalize a streaming hash calculation.

hash_init(Type)

Initialize the state for a streaming hash digest calculation.

hash_update(State, Data)

Add data to a streaming digest calculation.

hash_xof(Type, Data, Length)

Compute a message digest for an xof_algorithm.

Key API

compute_key(Type, OthersPublicKey, MyPrivateKey, Params)

Compute the shared secret from the private key and the other party's public key.

decapsulate_key(Type, MyPrivKey, EncapSecret)

Regenerate shared secret from encapsulated secret and private key.

encapsulate_key(Type, OthersPublicKey)

Generate encapsulated shared secret from the other party's public key.

generate_key(Type, Params)

Equivalent to generate_key/3.

generate_key(Type, Params, PrivKeyIn)

Generate a public key.

Legacy RSA Encryption API

private_decrypt(Algorithm, CipherText, PrivateKey, Options)

Decrypt using a private key.

private_encrypt(Algorithm, PlainText, PrivateKey, Options)

Encrypt using a private key.

public_decrypt(Algorithm, CipherText, PublicKey, Options)

Decrypt using a public key.

public_encrypt(Algorithm, PlainText, PublicKey, Options)

Encrypt using a public key.

MAC API

mac(Type, Key, Data)

Compute a poly1305 MAC (Message Authentication Code).

mac(Type, SubType, Key, Data)

Compute a MAC (Message Authentication Code).

mac_final(State)

Finalize a streaming MAC operation.

mac_finalN(State, MacLength)

Finalize a MAC operation with a custom length.

mac_init(Type, Key)

Initialize a state for streaming poly1305 MAC calculation.

mac_init(Type, SubType, Key)

Initialize the state for streaming MAC calculation.

mac_update(State0, Data)

Add data to a streaming MAC calculation.

macN(Type, Key, Data, MacLength)

Compute a poly1305 MAC (Message Authentication Code) with a limited length.

macN(Type, SubType, Key, Data, MacLength)

Compute a MAC (Message Authentication Code) with a limited length.

Plug-In Generators

rand_seed()

Create a generator for rand and save it in the process dictionary.

rand_seed_alg(Alg)

Create a generator for rand with specified algorithm, and save it in the process dictionary.

rand_seed_alg(Alg, Seed)

Create and seed a generator for rand with specified algorithm, and save it in the process dictionary.

rand_seed_alg_s/1

Create a generator for rand with specified algorithm.

rand_seed_alg_s(Alg, Seed)

Create and seed a generator for rand with specified algorithm.

rand_seed_s()

Create a generator for rand.

Random API

rand_seed(Seed)

Mixes in the bytes of the given binary into the internal state of OpenSSL's random number generator.

rand_uniform/2 deprecated

Generate a random integer number.

strong_rand_bytes(N)

Generate bytes with randomly uniform values 0..255.

strong_rand_range/1

Generate a random integer in a specified range.

Sign/Verify API

sign(Algorithm, DigestType, Msg, Key)

Equivalent to sign/5.

sign(Algorithm, DigestType, Msg, Key, Options)

Create a digital signature.

verify(Algorithm, DigestType, Msg, Signature, Key)

Equivalent to verify/6.

verify(Algorithm, DigestType, Msg, Signature, Key, Options)

Verify a digital signature.

Utility Functions

bytes_to_integer(Bin)

Convert binary representation, of an integer, to an Erlang integer.

cipher_info(Type)

Get information about a cipher algorithm.

ec_curve(CurveName)

Return the defining parameters of a elliptic curve.

ec_curves()

Return all supported named elliptic curves.

exor(Bin1, Bin2)

Perform bit-wise XOR (exclusive or) on the data supplied.

hash_equals(BinA, BinB)

Compare two binaries in constant time, such as results of HMAC computations.

hash_info(Type)

Get information about a hash algorithm.

info()

Get information about crypto and the OpenSSL backend.

info_fips()

Get information about the operating status of FIPS.

info_lib()

Get the name and version of the libraries used by crypto.

mod_pow(N, P, M)

Compute the function N^P mod M.

supports(Type)

Get which crypto algorithms that are supported by the underlying libcrypto library.

Types: Ciphers

cipher()

(not exported)

-type cipher() :: cipher_no_iv() | cipher_iv() | cipher_aead().

cipher_aead()

(not exported)

-type cipher_aead() ::
          aes_128_ccm | aes_192_ccm | aes_256_ccm | aes_ccm | aes_128_gcm | aes_192_gcm | aes_256_gcm |
          aes_gcm | sm4_gcm | sm4_ccm | chacha20_poly1305.

Ciphers known by the CRYPTO application.

Note that this list might be reduced if the underlying libcrypto does not support all of them.

cipher_iv()

(not exported)

-type cipher_iv() ::
          aes_128_cbc | aes_192_cbc | aes_256_cbc | aes_cbc | aes_128_ofb | aes_192_ofb | aes_256_ofb |
          aes_128_cfb128 | aes_192_cfb128 | aes_256_cfb128 | aes_cfb128 | aes_128_cfb8 | aes_192_cfb8 |
          aes_256_cfb8 | aes_cfb8 | aes_128_ctr | aes_192_ctr | aes_256_ctr | aes_ctr | sm4_cbc |
          sm4_ofb | sm4_cfb | sm4_ctr | blowfish_cbc | blowfish_cfb64 | blowfish_ofb64 | chacha20 |
          des_ede3_cbc | des_ede3_cfb | des_cbc | des_cfb | rc2_cbc.

cipher_no_iv()

(not exported)

-type cipher_no_iv() ::
          aes_128_ecb | aes_192_ecb | aes_256_ecb | aes_ecb | blowfish_ecb | des_ecb | sm4_ecb | rc4.

crypto_opt()

(not exported)

-type crypto_opt() :: {encrypt, boolean()} | {padding, padding()}.

Selects encryption ({encrypt,true}) or decryption ({encrypt,false}).

crypto_opts()

(not exported)

-type crypto_opts() :: boolean() | [crypto_opt()].

Equivalent to crypto_opt().

cryptolib_padding()

(not exported)

-type cryptolib_padding() :: none | pkcs_padding.

The cryptolib_padding are paddings that may be present in the underlying cryptolib linked to the Erlang/OTP crypto app.

For OpenSSL, see the OpenSSL documentation. and find EVP_CIPHER_CTX_set_padding() in cryptolib for your linked version.

otp_padding()

(not exported)

-type otp_padding() :: zero | random.

Erlang/OTP adds a either padding of zeroes or padding with random bytes.

padding()

(not exported)

-type padding() :: cryptolib_padding() | otp_padding().

This option handles padding in the last block. If not set, no padding is done and any bytes in the last unfilled block is silently discarded.

Types: Diffie-Hellman Keys and parameters

dh_params()

(not exported)

-type dh_params() :: [key_integer()].

dh_params() = [P, G] | [P, G, MaxPrivateKeyBitLength]

dh_private()

-type dh_private() :: key_integer().

dh_public()

-type dh_public() :: key_integer().

Equivalent to dh_private().

ecdh_params()

(not exported)

-type ecdh_params() :: ec_named_curve() | edwards_curve_dh() | ec_explicit_curve().

ecdh_private()

(not exported)

-type ecdh_private() :: key_integer().

Equivalent to ecdh_params().

ecdh_public()

(not exported)

-type ecdh_public() :: key_integer().

Equivalent to ecdh_params().

Types: Digests and hash

blake2()

(not exported)

-type blake2() :: blake2b | blake2s.

cmac_cipher_algorithm()

-type cmac_cipher_algorithm() ::
          aes_128_cbc | aes_192_cbc | aes_256_cbc | aes_cbc | blowfish_cbc | des_cbc | des_ede3_cbc |
          rc2_cbc.

compatibility_only_hash()

(not exported)

-type compatibility_only_hash() :: md5 | md4.

The compatibility_only_hash/0 algorithms are recommended only for compatibility with existing applications.

dss_digest_type()

-type dss_digest_type() :: sha1() | sha2().

ecdsa_digest_type()

-type ecdsa_digest_type() :: sha1() | sha2().

hash_algorithm()

(not exported)

-type hash_algorithm() ::
          sha1() | sha2() | sha3() | sha3_xof() | blake2() | ripemd160 | sm3 | compatibility_only_hash().

hash_xof_algorithm()

(not exported)

-type hash_xof_algorithm() :: sha3_xof().

hmac_hash_algorithm()

-type hmac_hash_algorithm() :: sha1() | sha2() | sha3() | sm3 | compatibility_only_hash().

rsa_digest_type()

-type rsa_digest_type() :: sha1() | sha2() | md5 | ripemd160.

sha1()

-type sha1() :: sha.

Equivalent to blake2().

sha2()

-type sha2() :: sha224 | sha256 | sha384 | sha512 | sha512_224 | sha512_256.

Equivalent to blake2().

sha3()

-type sha3() :: sha3_224 | sha3_256 | sha3_384 | sha3_512.

Equivalent to blake2().

sha3_xof()

(not exported)

-type sha3_xof() :: shake128 | shake256.

Equivalent to blake2().

Types: Elliptic Curves

ec_basis()

(not exported)

-type ec_basis() ::
          {tpbasis, K :: non_neg_integer()} |
          {ppbasis, K1 :: non_neg_integer(), K2 :: non_neg_integer(), K3 :: non_neg_integer()} |
          onbasis.

Curve definition details.

ec_characteristic_two_field()

(not exported)

-type ec_characteristic_two_field() :: {characteristic_two_field, M :: integer(), Basis :: ec_basis()}.

Equivalent to ec_basis().

ec_curve()

(not exported)

-type ec_curve() :: {A :: binary(), B :: binary(), Seed :: none | binary()}.

Parametric curve definition.

ec_explicit_curve()

(not exported)

-type ec_explicit_curve() ::
          {Field :: ec_field(),
           Curve :: ec_curve(),
           BasePoint :: binary(),
           Order :: binary(),
           CoFactor :: none | binary()}.

Equivalent to ec_curve().

ec_field()

(not exported)

-type ec_field() :: ec_prime_field() | ec_characteristic_two_field().

Equivalent to ec_curve().

ec_named_curve()

-type ec_named_curve() ::
          brainpoolP160r1 | brainpoolP160t1 | brainpoolP192r1 | brainpoolP192t1 | brainpoolP224r1 |
          brainpoolP224t1 | brainpoolP256r1 | brainpoolP256t1 | brainpoolP320r1 | brainpoolP320t1 |
          brainpoolP384r1 | brainpoolP384t1 | brainpoolP512r1 | brainpoolP512t1 | c2pnb163v1 |
          c2pnb163v2 | c2pnb163v3 | c2pnb176v1 | c2pnb208w1 | c2pnb272w1 | c2pnb304w1 | c2pnb368w1 |
          c2tnb191v1 | c2tnb191v2 | c2tnb191v3 | c2tnb239v1 | c2tnb239v2 | c2tnb239v3 | c2tnb359v1 |
          c2tnb431r1 | ipsec3 | ipsec4 | prime192v1 | prime192v2 | prime192v3 | prime239v1 |
          prime239v2 | prime239v3 | prime256v1 | secp112r1 | secp112r2 | secp128r1 | secp128r2 |
          secp160k1 | secp160r1 | secp160r2 | secp192k1 | secp192r1 | secp224k1 | secp224r1 |
          secp256k1 | secp256r1 | secp384r1 | secp521r1 | sect113r1 | sect113r2 | sect131r1 |
          sect131r2 | sect163k1 | sect163r1 | sect163r2 | sect193r1 | sect193r2 | sect233k1 |
          sect233r1 | sect239k1 | sect283k1 | sect283r1 | sect409k1 | sect409r1 | sect571k1 |
          sect571r1 | wtls1 | wtls10 | wtls11 | wtls12 | wtls3 | wtls4 | wtls5 | wtls6 | wtls7 | wtls8 |
          wtls9.

Equivalent to edwards_curve_ed().

ec_prime_field()

(not exported)

-type ec_prime_field() :: {prime_field, Prime :: integer()}.

Equivalent to ec_basis().

edwards_curve_dh()

(not exported)

-type edwards_curve_dh() :: x25519 | x448.

Equivalent to edwards_curve_ed().

edwards_curve_ed()

(not exported)

-type edwards_curve_ed() :: ed25519 | ed448.

Note that some curves are disabled if FIPS is enabled.

Types: Internal data types

crypto_state()

-opaque crypto_state()

Equivalent to mac_state().

hash_state()

-opaque hash_state()

Equivalent to mac_state().

mac_state()

-opaque mac_state()

Contexts with an internal state that should not be manipulated but passed between function calls.

Types: Key Encapsulation Mechanism

kem()

-type kem() :: mlkem512 | mlkem768 | mlkem1024.

Key encapsulation mechanisms.

Types: Keys

key_integer()

(not exported)

-type key_integer() :: integer() | binary().

Always binary/0 when used as return value

Types: Public Key Ciphers

pk_encrypt_decrypt_algs()

(not exported)

-type pk_encrypt_decrypt_algs() :: rsa.

Algorithms for public key encrypt/decrypt. Only RSA is supported.

pk_encrypt_decrypt_opts()

-type pk_encrypt_decrypt_opts() :: [rsa_opt()] | rsa_compat_opts().

Equivalent to rsa_padding().

rsa_compat_opts()

(not exported)

-type rsa_compat_opts() :: [{rsa_pad, rsa_padding()}] | rsa_padding().

Those option forms are kept only for compatibility and should not be used in new code.

rsa_opt()

(not exported)

-type rsa_opt() ::
          {rsa_padding, rsa_padding()} |
          {signature_md, atom()} |
          {rsa_mgf1_md, sha} |
          {rsa_oaep_label, binary()} |
          {rsa_oaep_md, sha}.

Equivalent to rsa_padding().

rsa_padding()

(not exported)

-type rsa_padding() :: rsa_pkcs1_padding | rsa_pkcs1_oaep_padding | rsa_x931_padding | rsa_no_padding.

Options for public key encrypt/decrypt. Only RSA is supported.

Warning

The RSA options are experimental.

The exact set of options and there syntax may be changed without prior notice.

Types: Public Key Sign and Verify

pk_sign_verify_algs()

(not exported)

-type pk_sign_verify_algs() :: rsa | dss | ecdsa | eddsa | mldsa() | slh_dsa().

Algorithms for sign and verify.

pk_sign_verify_opts()

-type pk_sign_verify_opts() :: [rsa_sign_verify_opt()].

Equivalent to rsa_sign_verify_padding().

rsa_sign_verify_opt()

(not exported)

-type rsa_sign_verify_opt() ::
          {rsa_padding, rsa_sign_verify_padding()} |
          {rsa_pss_saltlen, integer()} |
          {rsa_mgf1_md, sha2()}.

Equivalent to rsa_sign_verify_padding().

rsa_sign_verify_padding()

(not exported)

-type rsa_sign_verify_padding() ::
          rsa_pkcs1_padding | rsa_pkcs1_pss_padding | rsa_x931_padding | rsa_no_padding.

Options for sign and verify.

Warning

The RSA options are experimental.

The exact set of options and there syntax may be changed without prior notice.

Types: Public/Private Keys

dss_private()

(not exported)

-type dss_private() :: [key_integer()].

dss_public() = [P, Q, G, Y]

Where P, Q and G are the dss parameters and Y is the public key.

dss_private() = [P, Q, G, X]

Where P, Q and G are the dss parameters and X is the private key.

dss_public()

(not exported)

-type dss_public() :: [key_integer()].

Equivalent to dss_private().

ecdsa_params()

(not exported)

-type ecdsa_params() :: ec_named_curve() | ec_explicit_curve().

ecdsa_private()

(not exported)

-type ecdsa_private() :: key_integer().

Equivalent to ecdsa_params().

ecdsa_public()

(not exported)

-type ecdsa_public() :: key_integer().

Equivalent to ecdsa_params().

eddsa_params()

(not exported)

-type eddsa_params() :: edwards_curve_ed().

eddsa_private()

(not exported)

-type eddsa_private() :: key_integer().

Equivalent to eddsa_params().

eddsa_public()

(not exported)

-type eddsa_public() :: key_integer().

Equivalent to eddsa_params().

rsa_params()

(not exported)

-type rsa_params() :: {ModulusSizeInBits :: integer(), PublicExponent :: key_integer()}.

rsa_public() = [E, N]

rsa_private() = [E, N, D] | [E, N, D, P1, P2, E1, E2, C]

Where E is the public exponent, N is public modulus and D is the private exponent. The longer key format contains redundant information that will make the calculation faster. P1 and P2 are first and second prime factors. E1 and E2 are first and second exponents. C is the CRT coefficient. The terminology is taken from RFC 3447.

rsa_private()

(not exported)

-type rsa_private() :: [key_integer()].

Equivalent to rsa_params().

rsa_public()

(not exported)

-type rsa_public() :: [key_integer()].

Equivalent to rsa_params().

srp_comp_params()

(not exported)

-type srp_comp_params() :: {user, srp_user_comp_params()} | {host, srp_host_comp_params()}.

Equivalent to srp_host_comp_params().

srp_gen_params()

(not exported)

-type srp_gen_params() :: {user, srp_user_gen_params()} | {host, srp_host_gen_params()}.

Equivalent to srp_host_comp_params().

srp_host_comp_params()

(not exported)

-type srp_host_comp_params() :: [binary() | atom()].

Where Verifier is v, Generator is g and Prime isN, DerivedKey is X, and Scrambler is u (optional will be generated if not provided) from SRP design Version = '3' | '6' | '6a'

srp_host_gen_params()

(not exported)

-type srp_host_gen_params() :: [binary() | atom() | list()].

Equivalent to srp_host_comp_params().

srp_private()

(not exported)

-type srp_private() :: key_integer().

srp_public() = key_integer()

Where is A or B from SRP design

srp_private() = key_integer()

Where is a or b from SRP design

srp_public()

(not exported)

-type srp_public() :: key_integer().

Equivalent to srp_private().

srp_user_comp_params()

(not exported)

-type srp_user_comp_params() :: [binary() | atom()].

Equivalent to srp_host_comp_params().

srp_user_gen_params()

(not exported)

-type srp_user_gen_params() :: [binary() | atom() | list()].

Equivalent to srp_host_comp_params().

Types: Types for Engines

engine_cmnd()

(not exported)

-type engine_cmnd() :: {unicode:chardata(), unicode:chardata()}.

Pre and Post commands for engine_load/3 and /4.

engine_key_ref()

(not exported)

-type engine_key_ref() ::
          #{engine := engine_ref(), key_id := key_id(), password => password(), term() => term()}.

Equivalent to engine_ref().

engine_method_type()

(not exported)

-type engine_method_type() ::
          engine_method_rsa | engine_method_dsa | engine_method_dh | engine_method_rand |
          engine_method_ecdh | engine_method_ecdsa | engine_method_ciphers | engine_method_digests |
          engine_method_store | engine_method_pkey_meths | engine_method_pkey_asn1_meths |
          engine_method_ec.

engine_ref()

-type engine_ref() :: term().

The result of a call to engine_load/3.

key_id()

-type key_id() :: string() | binary().

Identifies the key to be used. The format depends on the loaded engine. It is passed to the ENGINE_load_(private|public)_key functions in libcrypto.

password()

-type password() :: string() | binary().

The password of the key stored in an engine.

Types

crypto_integer()

(not exported)

-type crypto_integer() :: binary() | integer().

mldsa()

-type mldsa() :: mldsa44 | mldsa65 | mldsa87.

mldsa_private()

(not exported)

-type mldsa_private() :: {seed | expandedkey, binary()}.

mldsa_public()

(not exported)

-type mldsa_public() :: binary().

rand_cache_state()

(not exported)

-type rand_cache_state() :: binary().

rand_plugin_aes_state()

(not exported)

-type rand_plugin_aes_state() :: dynamic().

rand_plugin_prng1_init_state()

(not exported)

-type rand_plugin_prng1_init_state() :: {cipher_iv(), binary(), binary(), binary()}.

rand_plugin_prng1_state()

(not exported)

-type rand_plugin_prng1_state() ::
          rand_plugin_prng1_init_state() | maybe_improper_list(binary(), {crypto_state(), binary()}).

rand_plugin_state()

(not exported)

-type rand_plugin_state() :: no_state.

slh_dsa()

-type slh_dsa() ::
          slh_dsa_shake_128s | slh_dsa_shake_128f | slh_dsa_sha2_128s | slh_dsa_sha2_128f |
          slh_dsa_shake_192s | slh_dsa_shake_192f | slh_dsa_sha2_192s | slh_dsa_sha2_192f |
          slh_dsa_shake_256s | slh_dsa_shake_256f | slh_dsa_sha2_256s | slh_dsa_sha2_256f.

slh_dsa_private()

(not exported)

-type slh_dsa_private() :: binary().

slh_dsa_public()

(not exported)

-type slh_dsa_public() :: binary().

Cipher API

crypto_final(State)

(since OTP 23.0)

-spec crypto_final(State) -> FinalResult when State :: crypto_state(), FinalResult :: binary().

Finalize a streaming encryptions or decryptions operation and delivers the final bytes of the final block.

The data returned from this function may be empty if no padding was enabled in crypto_init/3 or crypto_init/4.

Uses the 3-tuple style for error handling.

crypto_get_data(State)

(since OTP 23.0)

-spec crypto_get_data(State) -> Result when State :: crypto_state(), Result :: map().

Return information about a crypto_state/0.

The information returned is a map, which currently contains at least:

size - The number of bytes encrypted or decrypted so far.

padding_size - After a call to crypto_final/1 it contains the number of bytes padded. Otherwise 0.

padding_type - The type of the padding as provided in the call to crypto_init/3 or crypto_init/4.

encrypt - Is true if encryption is performed. It is false otherwise.

Uses the 3-tuple style for error handling.

crypto_init(Cipher, Key, FlagOrOptions)

(since OTP 22.0)

-spec crypto_init(Cipher, Key, FlagOrOptions) -> State
                     when
                         Cipher :: cipher_no_iv(),
                         Key :: iodata(),
                         FlagOrOptions :: crypto_opts() | boolean(),
                         State :: crypto_state().

Initialize the state for a streaming encryption or decryption operation.

Equivalent to the call crypto_init(Cipher, Key, <<>>, FlagOrOptions). It is intended for ciphers without an IV (nounce).

Uses the 3-tuple style for error handling.

crypto_init(Cipher, Key, IV, FlagOrOptions)

(since OTP 22.0)

-spec crypto_init(Cipher, Key, IV, FlagOrOptions) -> State
                     when
                         Cipher :: cipher_iv(),
                         Key :: iodata(),
                         IV :: iodata(),
                         FlagOrOptions :: crypto_opts(),
                         State :: crypto_state().

Initialize the state for a streaming encryptions or decryptions operation.

The returned state should be used as argument to crypto_update/2 and crypto_final/1 to do the actual encryption or decryption.

If IV = <<>>, no IV is used. This is intended for ciphers without an IV (nounce). See crypto_init/3.

For encryption, set the FlagOrOptions to true or [{encrypt,true}]. For decryption, set it to false or [{encrypt,false}].

Padding could be enabled with the option {padding,Padding}. The cryptolib_padding enables pkcs_padding or no padding (none). The paddings zero or random fills the last part of the last block with zeroes or random bytes. If the last block is already full, nothing is added.

In decryption, the cryptolib_padding removes such padding, if present. The otp_padding is not removed - it has to be done elsewhere.

If padding is {padding,none} or not specified and the total data from all subsequent crypto_updates does not fill the last block fully, that last data is lost. In case of {padding,none} there will be an error in this case. If padding is not specified, the bytes of the unfilled block is silently discarded.

The actual padding is performed by crypto_final/1.

For blocksizes call cipher_info/1.

Uses the 3-tuple style for error handling.

See examples in the User's Guide.

crypto_one_time(Cipher, Key, Data, FlagOrOptions)

(since OTP 22.0)

-spec crypto_one_time(Cipher, Key, Data, FlagOrOptions) -> Result
                         when
                             Cipher :: cipher_no_iv(),
                             Key :: iodata(),
                             Data :: iodata(),
                             FlagOrOptions :: crypto_opts() | boolean(),
                             Result :: binary().

Do a complete encrypt or decrypt of the full text.

As crypto_one_time/5 but for ciphers without IVs.

Uses the 3-tuple style for error handling.

crypto_one_time(Cipher, Key, IV, Data, FlagOrOptions)

(since OTP 22.0)

-spec crypto_one_time(Cipher, Key, IV, Data, FlagOrOptions) -> Result
                         when
                             Cipher :: cipher_iv(),
                             Key :: iodata(),
                             IV :: iodata(),
                             Data :: iodata(),
                             FlagOrOptions :: crypto_opts() | boolean(),
                             Result :: binary().

Do a complete encrypt or decrypt of the full text.

Argument Data is the text to be encrypted or decrypted.

For encryption, set the FlagOrOptions to true. For decryption, set it to false. For setting other options, see crypto_init/4.

Uses the 3-tuple style for error handling.

See examples in the User's Guide.

crypto_one_time_aead(State, IV, InText, AAD)

(since OTP 28.0)

-spec crypto_one_time_aead(State, IV, InText, AAD) -> Result
                              when
                                  State :: crypto_state(),
                                  IV :: iodata(),
                                  InText :: iodata(),
                                  AAD :: iodata(),
                                  Result :: EncryptResult | DecryptResult,
                                  EncryptResult :: binary(),
                                  DecryptResult :: binary() | error.

Do a complete encrypt or decrypt with an AEAD cipher of the full text.

Similar to 'crypto_one_time_aead/7' but uses the handle from 'crypto_one_time_aead_init/4'.

Appends the tag of the specified 'TagLength' to the end of the encrypted data, when doing encryption. Strips the tag from the end of 'InText' and verifies it when doing decryption.

crypto_one_time_aead(Cipher, Key, IV, InText, AAD, EncFlag)

(since OTP 22.0)

-spec crypto_one_time_aead(Cipher, Key, IV, InText, AAD, EncFlag :: true) -> Result
                              when
                                  Cipher :: cipher_aead(),
                                  Key :: iodata(),
                                  IV :: iodata(),
                                  InText :: iodata(),
                                  AAD :: iodata(),
                                  Result :: EncryptResult,
                                  EncryptResult :: {OutCryptoText, OutTag},
                                  OutCryptoText :: binary(),
                                  OutTag :: binary().

Do a complete encrypt with an AEAD cipher of the full text with the default tag length.

Equivalent to crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagLength, true) where TagLength is the default tag length for the given Cipher.

crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagOrTagLength, EncFlag)

(since OTP 22.0)

-spec crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagOrTagLength, EncFlag) -> Result
                              when
                                  Cipher :: cipher_aead(),
                                  Key :: iodata(),
                                  IV :: iodata(),
                                  InText :: iodata(),
                                  AAD :: iodata(),
                                  TagOrTagLength :: EncryptTagLength | DecryptTag,
                                  EncryptTagLength :: non_neg_integer(),
                                  DecryptTag :: iodata(),
                                  EncFlag :: boolean(),
                                  Result :: EncryptResult | DecryptResult,
                                  EncryptResult :: {OutCryptoText, OutTag},
                                  DecryptResult :: OutPlainText | error,
                                  OutCryptoText :: binary(),
                                  OutTag :: binary(),
                                  OutPlainText :: binary().

Do a complete encrypt or decrypt with an AEAD cipher of the full text.

For encryption, set the EncryptFlag to true and set the TagOrTagLength to the wanted size (in bytes) of the tag, that is, the tag length. If the default length is wanted, the crypto_one_time_aead/6 form may be used.

For decryption, set the EncryptFlag to false and put the tag to be checked in the argument TagOrTagLength.

Warning

The length of the tag at decryption is not checked by the function. It is the caller's responsibility to ensure that the length of the tag matches the length of the tag used when the data was encrypted. Otherwise the decryption may succeed if the given tag only matches the start of the proper tag.

Additional Authentication Data (AAD) is plaintext data that will not be encrypted, but will be covered by authenticity protection. It should be provided through the AAD argument, but can be an empty binary as well (<<>>) if not needed. In that case, a plain AE (Authenticated Encryption) is performed instead of AEAD (Authenticated Encryption with Associated Data). This function only supports ciphers that can be used both with and without AAD.

Uses the 3-tuple style for error handling.

See examples in the User's Guide.

crypto_one_time_aead_init(Cipher, Key, TagLength, EncFlag)

(since OTP 28.0)

-spec crypto_one_time_aead_init(Cipher, Key, TagLength, EncFlag) -> Result
                                   when
                                       Cipher :: cipher_aead(),
                                       Key :: iodata(),
                                       TagLength :: non_neg_integer(),
                                       EncFlag :: boolean(),
                                       Result :: crypto_state().

Initializes AEAD cipher.

Similar to 'crypto_one_time_aead/7' but only does the initialization part, returns a handle that can be used with 'crypto_one_time_aead/4' serveral times.

crypto_update(State, Data)

(since OTP 22.0)

-spec crypto_update(State, Data) -> Result
                       when State :: crypto_state(), Data :: iodata(), Result :: binary().

Add data to a streaming encryption or decryption operation.

If the part is less than a number of full blocks, only the full blocks (possibly none) are encrypted or decrypted and the remaining bytes are saved to the next crypto_update operation. The State should be created with crypto_init/3 or crypto_init/4.

Uses the 3-tuple style for error handling.

See examples in the User's Guide.

Deprecated API

enable_fips_mode(Enable)

(since OTP 21.1)

This function is deprecated. crypto:enable_fips_mode/1 is deprecated; use config parameter fips_mode.

-spec enable_fips_mode(Enable) -> Result when Enable :: boolean(), Result :: boolean().

Enable or disable FIPs mode.

Argument Enable should be true to enable and false to disable FIPS mode. Returns true if the operation was successful or false otherwise.

Note that to enable FIPS mode successfully, OTP must be built with the configure option --enable-fips, and the underlying libcrypto must also support FIPS.

See also info_fips/0.

start()

This function is deprecated. crypto:start/0 is deprecated; use application:start(crypto) instead.

-spec start() -> ok | {error, Reason :: term()}.

Use application:start(crypto) instead.

Warning

This function does not work if FIPS mode is to be enabled. FIPS mode will be disabled even if configuration parameter fips_mode is set to true. Use application:start(crypto) instead.

stop()

This function is deprecated. crypto:stop/0 is deprecated; use application:stop(crypto) instead.

-spec stop() -> ok | {error, Reason :: term()}.

Use application:stop(crypto) instead.

Engine API

engine_add(Engine)

(since OTP 21.0.6)

-spec engine_add(Engine) -> Result when Engine :: engine_ref(), Result :: ok | {error, Reason :: term()}.

Add the engine to OpenSSL's internal list.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_by_id(EngineId)

(since OTP 21.0.6)

-spec engine_by_id(EngineId) -> Result
                      when
                          EngineId :: unicode:chardata(),
                          Result :: {ok, Engine :: engine_ref()} | {error, Reason :: term()}.

Get a reference to an already loaded engine with EngineId. An error tuple is returned if the engine cannot be unloaded.

The function raises a error:badarg if the parameter is in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_ctrl_cmd_string(Engine, CmdName, CmdArg)

(since OTP 20.2)

-spec engine_ctrl_cmd_string(Engine, CmdName, CmdArg) -> Result
                                when
                                    Engine :: term(),
                                    CmdName :: unicode:chardata(),
                                    CmdArg :: unicode:chardata(),
                                    Result :: ok | {error, Reason :: term()}.

Send ctrl commands to an OpenSSL engine.

This function is the same as calling engine_ctrl_cmd_string/4 with Optional set to false.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional)

(since OTP 20.2)

-spec engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional) -> Result
                                when
                                    Engine :: term(),
                                    CmdName :: unicode:chardata(),
                                    CmdArg :: unicode:chardata(),
                                    Optional :: boolean(),
                                    Result :: ok | {error, Reason :: term()}.

Send ctrl commands to an OpenSSL engine.

Optional is a boolean argument that can relax the semantics of the function. If set to true it will only return failure if the ENGINE supported the given command name but failed while executing it, if the ENGINE does not support the command name it will simply return success without doing anything. In this case we assume the user is only supplying commands specific to the given ENGINE so we set this to false.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_get_all_methods()

(since OTP 20.2)

-spec engine_get_all_methods() -> Result when Result :: [engine_method_type()].

Return a list of all possible engine methods.

May raise exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_get_id(Engine)

(since OTP 21.0.6)

-spec engine_get_id(Engine) -> EngineId when Engine :: engine_ref(), EngineId :: unicode:chardata().

Return the ID for the engine, or an empty binary if there is no id set.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_get_name(Engine)

(since OTP 21.0.6)

-spec engine_get_name(Engine) -> EngineName
                         when Engine :: engine_ref(), EngineName :: unicode:chardata().

Return the name (eg a description) for the engine, or an empty binary if there is no name set.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_list()

(since OTP 20.2)

-spec engine_list() -> Result when Result :: [EngineId :: unicode:chardata()].

List the id's of all engines in OpenSSL's internal list.

It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

May raise exception error:notsup in case engine functionality is not supported by the underlying OpenSSL implementation.

engine_load(EngineId, PreCmds, PostCmds)

(since OTP 20.2)

-spec engine_load(EngineId, PreCmds, PostCmds) -> Result
                     when
                         EngineId :: unicode:chardata(),
                         PreCmds :: [engine_cmnd()],
                         PostCmds :: [engine_cmnd()],
                         Result :: {ok, Engine :: engine_ref()} | {error, Reason :: term()}.

Load an OpenSSL engine.

Loads the OpenSSL engine given by EngineId if it is available and intialize it. Returns ok and an engine handle, or if the engine cannot be loaded an error tuple is returned.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_register(Engine, EngineMethods)

(since OTP 25.1)

-spec engine_register(Engine, EngineMethods) -> Result
                         when
                             Engine :: engine_ref(),
                             EngineMethods :: [engine_method_type()],
                             Result :: ok | {error, Reason :: term()}.

Register engine to handle some type of methods, for example engine_method_digests.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_remove(Engine)

(since OTP 21.0.6)

-spec engine_remove(Engine) -> Result
                       when Engine :: engine_ref(), Result :: ok | {error, Reason :: term()}.

Remove the engine from OpenSSL's internal list.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_unload(Engine)

(since OTP 20.2)

-spec engine_unload(Engine) -> Result
                       when Engine :: engine_ref(), Result :: ok | {error, Reason :: term()}.

Unload an OpenSSL engine.

Unloads the OpenSSL engine given by Engine. An error tuple is returned if the engine cannot be unloaded.

The function raises a error:badarg if the parameter is in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_unregister(Engine, EngineMethods)

(since OTP 25.1)

-spec engine_unregister(Engine, EngineMethods) -> Result
                           when
                               Engine :: engine_ref(),
                               EngineMethods :: [engine_method_type()],
                               Result :: ok | {error, Reason :: term()}.

Unregister engine so it does not handle some type of methods.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

ensure_engine_loaded(EngineId, LibPath)

(since OTP 21.0.6)

-spec ensure_engine_loaded(EngineId, LibPath) -> Result
                              when
                                  EngineId :: unicode:chardata(),
                                  LibPath :: unicode:chardata(),
                                  Result :: {ok, Engine :: engine_ref()} | {error, Reason :: term()}.

Load a dynamic engine if not already done.

Loada the engine given by EngineId and the path to the dynamic library implementing the engine. An error tuple is returned if the engine cannot be loaded.

This function differs from the normal engine_load in the sense that it also add the engine id to OpenSSL's internal engine list. The difference between the first call and the following is that the first loads the engine with the dynamical engine and the following calls fetch it from the OpenSSL's engine list. All references that is returned are equal.

Use engine_unload/1 function to remove the references. But remember that engine_unload/1 just removes the references to the engine and not the tag in OpenSSL's engine list. That has to be done with the engine_remove/1 function when needed (just called once, from any of the references you got).

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

pbkdf2_hmac(Digest, Pass, Salt, Iter, KeyLen)

(since OTP 24.2)

-spec pbkdf2_hmac(Digest, Pass, Salt, Iter, KeyLen) -> Result
                     when
                         Digest :: sha | sha224 | sha256 | sha384 | sha512 | sha512_224 | sha512_256,
                         Pass :: binary(),
                         Salt :: binary(),
                         Iter :: pos_integer(),
                         KeyLen :: pos_integer(),
                         Result :: binary().

PKCS #5 PBKDF2 (Password-Based Key Derivation Function 2) in combination with HMAC.

Uses the 3-tuple style for error handling.

privkey_to_pubkey(Type, EnginePrivateKeyRef)

(since OTP 20.2)

-spec privkey_to_pubkey(Type, EnginePrivateKeyRef) -> PublicKey
                           when
                               Type :: rsa | dss,
                               EnginePrivateKeyRef :: engine_key_ref(),
                               PublicKey :: rsa_public() | dss_public().

Fetch public key from a private key stored in an Engine.

The key must be of the type indicated by the Type parameter.

Hash API

hash(Type, Data)

(since OTP R15B02)

-spec hash(Type, Data) -> Digest when Type :: hash_algorithm(), Data :: iodata(), Digest :: binary().

Compute a message digest.

Argument Type is the digest type and argument Data is the full message.

Uses the 3-tuple style for error handling.

hash_final(State)

(since OTP R15B02)

-spec hash_final(State) -> Digest when State :: hash_state(), Digest :: binary().

Finalize a streaming hash calculation.

Argument State as returned from the last call to hash_update. The size of Digest is determined by the type of hash function used to generate it.

Uses the 3-tuple style for error handling.

hash_init(Type)

(since OTP R15B02)

-spec hash_init(Type) -> State when Type :: hash_algorithm(), State :: hash_state().

Initialize the state for a streaming hash digest calculation.

Argument Type determines which digest to use. The returned state should be used as argument to hash_update/2.

Uses the 3-tuple style for error handling.

hash_update(State, Data)

(since OTP R15B02)

-spec hash_update(State, Data) -> NewState
                     when State :: hash_state(), NewState :: hash_state(), Data :: iodata().

Add data to a streaming digest calculation.

Update the digest using the given Data of any length.

Argument State must have been generated by hash_init or a previous call to this function.

Returns NewState that must be passed into the next call to hash_update/2 or hash_final/1.

Uses the 3-tuple style for error handling.

hash_xof(Type, Data, Length)

(since OTP 26.0)

-spec hash_xof(Type, Data, Length) -> Digest
                  when
                      Type :: hash_xof_algorithm(),
                      Data :: iodata(),
                      Length :: non_neg_integer(),
                      Digest :: binary().

Compute a message digest for an xof_algorithm.

Argument Type is the type of digest, Data is the full text and Length is the digest length in bits.

Uses the 3-tuple style for error handling.

May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.

Key API

compute_key(Type, OthersPublicKey, MyPrivateKey, Params)

(since OTP R16B01)

-spec compute_key(Type, OthersPublicKey, MyPrivateKey, Params) -> SharedSecret
                     when
                         Type :: dh | ecdh | eddh | srp,
                         SharedSecret :: binary(),
                         OthersPublicKey :: dh_public() | ecdh_public() | srp_public(),
                         MyPrivateKey :: dh_private() | ecdh_private() | {srp_public(), srp_private()},
                         Params :: dh_params() | ecdh_params() | srp_comp_params().

Compute the shared secret from the private key and the other party's public key.

See also public_key:compute_key/2.

Uses the 3-tuple style for error handling.

decapsulate_key(Type, MyPrivKey, EncapSecret)

(since OTP 28.1)

-spec decapsulate_key(Type, MyPrivKey, EncapSecret) -> Secret
                         when
                             Type :: kem(),
                             MyPrivKey :: binary(),
                             EncapSecret :: binary(),
                             Secret :: binary().

Regenerate shared secret from encapsulated secret and private key.

Returns a shared secret for encryption/decryption by local party.

Supported encapsulation methods can be obtained with supports(kems).

encapsulate_key(Type, OthersPublicKey)

(since OTP 28.1)

-spec encapsulate_key(Type, OthersPublicKey) -> {Secret, EncapSecret}
                         when
                             Type :: kem(),
                             OthersPublicKey :: binary(),
                             Secret :: binary(),
                             EncapSecret :: binary().

Generate encapsulated shared secret from the other party's public key.

Returns both a shared secret for encryption/decryption by local party and an encapsulated format of the same secret to be safely sent to the other party. With its private key, the other party can decapsulate the received secret (with decapsulate_key/3 for example) to regenerate the same shared secret.

Supported encapsulation methods can be obtained with supports(kems).

generate_key(Type, Params)

(since OTP R16B01)

-spec generate_key(Type, Params) -> {PublicKey, PrivKeyOut}
                      when
                          Type ::
                              dh | ecdh | eddh | eddsa | rsa |
                              mldsa() |
                              mlkem512 | mlkem768 | mlkem1024 |
                              slh_dsa() |
                              srp,
                          PublicKey :: dh_public() | ecdh_public() | rsa_public() | srp_public(),
                          PrivKeyOut ::
                              dh_private() |
                              ecdh_private() |
                              rsa_private() |
                              {srp_public(), srp_private()},
                          Params ::
                              dh_params() |
                              ecdh_params() |
                              eddsa_params() |
                              rsa_params() |
                              srp_gen_params() |
                              [].

Equivalent to generate_key/3.

generate_key(Type, Params, PrivKeyIn)

(since OTP R16B01)

-spec generate_key(Type, Params, PrivKeyIn) -> {PublicKey, PrivKeyOut}
                      when
                          Type ::
                              dh | ecdh | eddh | eddsa | rsa |
                              mldsa() |
                              mlkem512 | mlkem768 | mlkem1024 | srp |
                              slh_dsa(),
                          PublicKey :: dh_public() | ecdh_public() | rsa_public() | srp_public(),
                          PrivKeyIn ::
                              undefined |
                              dh_private() |
                              ecdh_private() |
                              rsa_private() |
                              {srp_public(), srp_private()},
                          PrivKeyOut ::
                              dh_private() |
                              ecdh_private() |
                              rsa_private() |
                              {srp_public(), srp_private()},
                          Params ::
                              dh_params() |
                              ecdh_params() |
                              eddsa_params() |
                              rsa_params() |
                              srp_comp_params() |
                              [].

Generate a public key.

See also public_key:generate_key/1.

Uses the 3-tuple style for error handling.

Note

If the linked version of cryptolib is OpenSSL 3.0

and the Type is dh (diffie-hellman)

and the parameter P (in dh_params/0) is one of the MODP groups (see RFC 3526)

and the optional MaxPrivateKeyBitLength parameter (in dh_params/0) is present,

then the optional key length parameter must be at least 224, 256, 302, 352 and 400 for group sizes of 2048, 3072, 4096, 6144 and 8192, respectively.

Legacy RSA Encryption API

private_decrypt(Algorithm, CipherText, PrivateKey, Options)

(since OTP R16B01)

-spec private_decrypt(Algorithm, CipherText, PrivateKey, Options) -> PlainText
                         when
                             Algorithm :: pk_encrypt_decrypt_algs(),
                             CipherText :: binary(),
                             PrivateKey :: rsa_private() | engine_key_ref(),
                             Options :: pk_encrypt_decrypt_opts(),
                             PlainText :: binary().

Decrypt using a private key.

Decrypts the CipherText, encrypted with public_encrypt/4 (or equivalent function) using the PrivateKey, and returns the plaintext (message digest). This is a low level signature verification operation used for instance by older versions of the SSL protocol. See also public_key:decrypt_private/2,3

Uses the 3-tuple style for error handling.

Warning

This is a legacy function, for security reasons do not use with rsa_pkcs1_padding.

private_encrypt(Algorithm, PlainText, PrivateKey, Options)

(since OTP R16B01)

-spec private_encrypt(Algorithm, PlainText, PrivateKey, Options) -> CipherText
                         when
                             Algorithm :: pk_encrypt_decrypt_algs(),
                             PlainText :: binary(),
                             PrivateKey :: rsa_private() | engine_key_ref(),
                             Options :: pk_encrypt_decrypt_opts(),
                             CipherText :: binary().

Encrypt using a private key.

Encrypts the PlainText using the PrivateKey and returns the ciphertext. This is a low level signature operation used for instance by older versions of the SSL protocol. See also public_key:encrypt_private/2,3

Uses the 3-tuple style for error handling.

Public-key decryption using the private key. See also crypto:private_decrypt/4

Warning

This is a legacy function, for security reasons do not use with rsa_pkcs1_padding. For digital signatures use of sign/4 together with verify/5 is the prefered solution.

public_decrypt(Algorithm, CipherText, PublicKey, Options)

(since OTP R16B01)

-spec public_decrypt(Algorithm, CipherText, PublicKey, Options) -> PlainText
                        when
                            Algorithm :: pk_encrypt_decrypt_algs(),
                            CipherText :: binary(),
                            PublicKey :: rsa_public() | engine_key_ref(),
                            Options :: pk_encrypt_decrypt_opts(),
                            PlainText :: binary().

Decrypt using a public key.

Decrypts the CipherText, encrypted with private_encrypt/4(or equivalent function) using the PublicKey, and returns the plaintext (message digest). This is a low level signature verification operation used for instance by older versions of the SSL protocol. See also public_key:decrypt_public/2,3

Uses the 3-tuple style for error handling.

Warning

This is a legacy function, for security reasons do not use with rsa_pkcs1_padding. For digital signatures use of verify/5 together with sign/4 is the prefered solution.

public_encrypt(Algorithm, PlainText, PublicKey, Options)

(since OTP R16B01)

-spec public_encrypt(Algorithm, PlainText, PublicKey, Options) -> CipherText
                        when
                            Algorithm :: pk_encrypt_decrypt_algs(),
                            PlainText :: binary(),
                            PublicKey :: rsa_public() | engine_key_ref(),
                            Options :: pk_encrypt_decrypt_opts(),
                            CipherText :: binary().

Encrypt using a public key.

Encrypts the PlainText (message digest) using the PublicKey and returns the CipherText. This is a low level signature operation used for instance by older versions of the SSL protocol. See also public_key:encrypt_public/2,3

Uses the 3-tuple style for error handling.

Warning

This is a legacy function, for security reasons do not use together with rsa_pkcs1_padding.

MAC API

mac(Type, Key, Data)

(since OTP 22.1)

-spec mac(Type :: poly1305, Key, Data) -> Mac when Key :: iodata(), Data :: iodata(), Mac :: binary().

Compute a poly1305 MAC (Message Authentication Code).

Same as mac(Type, undefined, Key, Data).

Uses the 3-tuple style for error handling.

mac(Type, SubType, Key, Data)

(since OTP 22.1)

-spec mac(Type, SubType, Key, Data) -> Mac
             when
                 Type :: hmac | cmac | poly1305,
                 SubType :: hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined,
                 Key :: iodata(),
                 Data :: iodata(),
                 Mac :: binary().

Compute a MAC (Message Authentication Code).

Argument Type is the type of MAC and Data is the full message.

SubType depends on the MAC Type:

For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.

For cmac it is a cipher suitable for cmac, see Algorithm Details in the User's Guide.

For poly1305 it should be set to undefined or the mac/2 function could be used instead, see Algorithm Details in the User's Guide.

Key is the authentication key with a length according to the Type and SubType. The key length could be found with the hash_info/1 (hmac) for and cipher_info/1 (cmac) functions. For poly1305 the key length is 32 bytes. Note that the cryptographic quality of the key is not checked.

The Mac result will have a default length depending on the Type and SubType. To set a shorter length, use macN/4 or macN/5 instead. The default length is documented in Algorithm Details in the User's Guide.

Uses the 3-tuple style for error handling.

mac_final(State)

(since OTP 22.1)

-spec mac_final(State) -> Mac when State :: mac_state(), Mac :: binary().

Finalize a streaming MAC operation.

Argument State is the state as returned by the last call to mac_update/2.

The Mac result will have a default length depending on the Type and SubType in the mac_init/2,3 call. To set a shorter length, use mac_finalN/2 instead. The default length is documented in Algorithm Details in the User's Guide.

Uses the 3-tuple style for error handling.

mac_finalN(State, MacLength)

(since OTP 22.1)

-spec mac_finalN(State, MacLength) -> Mac
                    when State :: mac_state(), MacLength :: pos_integer(), Mac :: binary().

Finalize a MAC operation with a custom length.

Argument State is the state as returned by the last call to mac_update/2.

Mac will be a binary with at most MacLength bytes. Note that if MacLength is greater than the actual number of bytes returned from the underlying hash, the returned hash will have that shorter length instead.

The max MacLength is documented in Algorithm Details in the User's Guide.

Uses the 3-tuple style for error handling.

mac_init(Type, Key)

(since OTP 22.1)

-spec mac_init(Type :: poly1305, Key) -> State when Key :: iodata(), State :: mac_state().

Initialize a state for streaming poly1305 MAC calculation.

Same as mac_init(Type, undefined, Key).

Uses the 3-tuple style for error handling.

mac_init(Type, SubType, Key)

(since OTP 22.1)

-spec mac_init(Type, SubType, Key) -> State
                  when
                      Type :: hmac | cmac | poly1305,
                      SubType :: hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined,
                      Key :: iodata(),
                      State :: mac_state().

Initialize the state for streaming MAC calculation.

Type determines which mac algorithm to use in the MAC operation.

SubType depends on the MAC Type:

For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.

For cmac it is a cipher suitable for cmac, see Algorithm Details in the User's Guide.

For poly1305 it should be set to undefined or the mac/2 function could be used instead, see Algorithm Details in the User's Guide.

Key is the authentication key with a length according to the Type and SubType. The key length could be found with the hash_info/1 (hmac) for and cipher_info/1 (cmac) functions. For poly1305 the key length is 32 bytes. Note that the cryptographic quality of the key is not checked.

The returned State should be used in one or more subsequent calls to mac_update/2. The MAC value is finally returned by calling mac_final/1 or mac_finalN/2.

Uses the 3-tuple style for error handling.

See examples in the User's Guide.

mac_update(State0, Data)

(since OTP 22.1)

-spec mac_update(State0, Data) -> State
                    when Data :: iodata(), State0 :: mac_state(), State :: mac_state().

Add data to a streaming MAC calculation.

Update the MAC represented by State0 using the given Data which could be of any length.

The State0 is the State value originally from a MAC init function, that is mac_init/2, mac_init/3 or the last call to mac_update/2. The value State0 is returned unchanged by the function as a reference to a mutated internal state. Hence, it is not possible to branch off a data stream by reusing old states.

Uses the 3-tuple style for error handling.

macN(Type, Key, Data, MacLength)

(since OTP 22.1)

-spec macN(Type :: poly1305, Key, Data, MacLength) -> Mac
              when Key :: iodata(), Data :: iodata(), Mac :: binary(), MacLength :: pos_integer().

Compute a poly1305 MAC (Message Authentication Code) with a limited length.

Same as macN(Type, undefined, Key, Data, MacLength).

Uses the 3-tuple style for error handling.

macN(Type, SubType, Key, Data, MacLength)

(since OTP 22.1)

-spec macN(Type, SubType, Key, Data, MacLength) -> Mac
              when
                  Type :: hmac | cmac | poly1305,
                  SubType :: hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined,
                  Key :: iodata(),
                  Data :: iodata(),
                  Mac :: binary(),
                  MacLength :: pos_integer().

Compute a MAC (Message Authentication Code) with a limited length.

Works like mac/3 and mac/4 but MacLength will limit the size of the resultant Mac to at most MacLength bytes. Note that if MacLength is greater than the actual number of bytes returned from the underlying hash, the returned hash will have that shorter length instead.

The max MacLength is documented in Algorithm Details in the User's Guide.

Plug-In Generators

rand_seed()

(since OTP 20.0)

-spec rand_seed() -> {rand:alg_handler(crypto), rand_plugin_state()}.

Create a generator for rand and save it in the process dictionary.

Equivalent to rand_seed_s/0 but also saves the returned state object (generator) in the process dictionary. That is, it is equivalent to rand:seed(rand_seed_s()).

See rand:seed/1 and rand_seed_s/0.

Example

_ = crypto:rand_seed(),
IntegerValue = rand:uniform(42), % 1 .. 42
FloatValue = rand:uniform().     % [0.0, 1.0)

Note

Note that when using the process dictionary for cryptographically secure random numbers one has to ensure that no code called between initializing the generator and between generating numbers accidentally alters the generator state in the process dictionary.

The safe approach is to use the rand functions that do not use the process dictionary but take an explicit state argument: the ones suffixed _s. Thereby it is rather rand_seed_s/0 that should be used instead of this function.

rand_seed_alg(Alg)

(since OTP 21.0)

-spec rand_seed_alg(Alg :: crypto) -> {rand:alg_handler(crypto), rand_plugin_state()};
                   (Alg :: crypto_cache) -> {rand:alg_handler(crypto_cache), rand_cache_state()};
                   (ExportState :: {crypto, rand_plugin_state()}) ->
                       {rand:alg_handler(crypto), rand_plugin_state()};
                   (ExportState :: {crypto_cache, rand_cache_state()}) ->
                       {rand:alg_handler(crypto_cache), rand_cache_state()};
                   (ExportState :: {crypto_aes, rand_plugin_aes_state()}) ->
                       {rand:alg_handler(crypto_aes), rand_plugin_aes_state()};
                   (ExportState :: {crypto_prng1, rand_plugin_prng1_init_state()}) ->
                       {rand:alg_handler(crypto_prng1), rand_plugin_prng1_init_state()};
                   (State) -> State
                       when
                           State ::
                               {rand:alg_handler(crypto), rand_plugin_state()} |
                               {rand:alg_handler(crypto_cache), rand_cache_state()} |
                               {rand:alg_handler(crypto_aes), rand_plugin_aes_state()} |
                               {rand:alg_handler(crypto_prng1), rand_plugin_prng1_state()}.

Create a generator for rand with specified algorithm, and save it in the process dictionary.

Equivalent to rand_seed_alg_s/1 but also saves the returned state object (generator) in the process dictionary. That is, equivalent to rand:seed(rand_seed_alg_s(Alg)).

See rand:seed/1 and rand_seed_alg_s/1. Note the warning about the usage of the process dictionary in rand_seed/0.

Example

_ = crypto:rand_seed_alg(crypto_cache),
IntegerValue = rand:uniform(42), % 1 .. 42
FloatValue = rand:uniform().     % [0.0, 1.0)

rand_seed_alg(Alg, Seed)

(since OTP-22.0)

-spec rand_seed_alg(Alg :: crypto_aes, Seed :: iodata()) ->
                       {rand:alg_handler(crypto_aes), rand_plugin_aes_state()};
                   (Alg :: crypto_prng1, Seed :: iodata()) ->
                       {rand:alg_handler(crypto_prng1), rand_plugin_prng1_state()}.

Create and seed a generator for rand with specified algorithm, and save it in the process dictionary.

Equivalent to rand_seed_alg_s/2 but also saves the returned state object (generator) in the process dictionary. That is, equivalent to rand:seed(rand_seed_alg_s(Alg, Seed)).

See rand:seed/1 and rand_seed_alg_s/2. Note the warning about the usage of the process dictionary in rand_seed/0.

Example

_ = crypto:rand_seed_alg(crypto_aes, "my seed"),
IntegerValue = rand:uniform(42), % 1 .. 42
FloatValue = rand:uniform(),     % [0.0, 1.0)
_ = crypto:rand_seed_alg(crypto_aes, "my seed"),
IntegerValue = rand:uniform(42), % Same values
FloatValue = rand:uniform().     % again

rand_seed_alg_s/1

(since OTP 21.0)

-spec rand_seed_alg_s(Alg :: crypto) -> {rand:alg_handler(crypto), rand_plugin_state()};
                     (Alg :: crypto_cache) -> {rand:alg_handler(crypto_cache), rand_cache_state()};
                     (ExportState :: {crypto, rand_plugin_state()}) ->
                         {rand:alg_handler(crypto), rand_plugin_state()};
                     (ExportState :: {crypto_cache, rand_cache_state()}) ->
                         {rand:alg_handler(crypto_cache), rand_cache_state()};
                     (ExportState :: {crypto_aes, rand_plugin_aes_state()}) ->
                         {rand:alg_handler(crypto_aes), rand_plugin_aes_state()};
                     (ExportState :: {crypto_prng1, rand_plugin_prng1_init_state()}) ->
                         {rand:alg_handler(crypto_prng1), rand_plugin_prng1_init_state()};
                     (State) -> State
                         when
                             State ::
                                 {rand:alg_handler(crypto), rand_plugin_state()} |
                                 {rand:alg_handler(crypto_cache), rand_cache_state()} |
                                 {rand:alg_handler(crypto_aes), rand_plugin_aes_state()} |
                                 {rand:alg_handler(crypto_prng1), rand_plugin_prng1_state()}.

Create a generator for rand with specified algorithm.

Create a state object (generator) for random number generation, which when used by the rand functions produce cryptographically strong random number.

See rand:seed_s/1 and for example rand:uniform_s/2.

With Alg = crypto

The created generator uses OpenSSL's BN_rand_range for uniform integers and floats.

The generator also implements generating bytes efficiently with OpenSSL's RAND_bytes, just like strong_rand_bytes/1. See also rand:bytes_s/2. Since OTP @OTP-19882@.

Because the OpenSSL library is called for every request, this generator has got a very small generator state, but a large call overhead, so for numbers and small numbers of bytes (about 10), it becomes very slow compared to the default PRNG in the rand module. This is an unfair comparison because a PRNG is not cryptographically strong. Still, for a larger numbers of bytes, (about 1 000 or more) this generator is the fastest.

This function is equivalent to rand_seed_s/0.

With Alg = crypto_cache

The created generator fetches random data with OpenSSL's RAND_bytes, just like strong_rand_bytes/1, and caches it in the generator's state. Then 56 bit numbers are extracted from the cache, which makes operations in module rand fast on 64 bit machines.

The generator also implements extracting bytes efficiently. See also rand:bytes_s/2. Since OTP @OTP-19882@.

Caching random data improves amortized performance a lot so for numbers it becomes less than a factor 2 slower than the default PRNG in the rand module. For bytes it performs very much like for Alg = crypto above.

Since this generator caches random data it is a bad idea to copy its state in an attempt to fork into multiple generators. The forked generators will produce the same numbers until their caches are empty, which cannot be regarded as cryptographically strong, and is probably never useful.

Example

S0 = crypto:rand_seed_alg_s(crypto_cache),
{IntegerValue, S1} = rand:uniform(42, S0), % 1 .. 42
{FloatValue, S2} = rand:uniform(S1).       % [0.0, 1.0)

These generators may cause the rand functions using the returned state object to raise the exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

The cache size can be changed from its default value using the crypto app's configuration parameter rand_cache_size.

Note

The state returned from this function cannot be used to get a reproducible random sequence as from the other rand functions, since that would not be cryptographically safe.

In fact when random data is cached some numbers may get reproduced, but this is unpredictable.

The only supported usage is to generate one distinct random sequence.

With argument ExportState

For completeness, this function accepts an ExportState from rand:export_seed_s/1 used on one of this module's generators. This function can probably only be useful for algorithm crypto_aes.

For algorithm crypto it is not very useful since the produced numbers are as unpredictable for a new generator as for one re-created with this function.

The same goes for algorithm crypto_cache, but its exported state may contain cached random numbers which might delay having to call OpenSSL the first time, so there is a possible slight performance gain.

For algorithm crypto_aes this function works as described in rand:export_seed_s/1 and rand:seed_s/1.

For algorithm crypto_prng1 this function only works as described in rand:export_seed_s/1 and rand:seed_s/1 on the initial state after creation (seeding). After the first random number has been created, the state contains a crypto_state/0 that does not survive a roundtrip through Erlang's external term format.

With argument State

For completeness, this function accepts a State just as rand:seed_s does. Calling this function with a State from one of the algorithms in this module only passes the state through, it is a no-op.

rand_seed_alg_s(Alg, Seed)

(since OTP 22.0)

-spec rand_seed_alg_s(Alg :: crypto_aes, Seed :: iodata()) ->
                         {rand:alg_handler(crypto_aes), rand_plugin_aes_state()};
                     (Alg :: crypto_prng1, Seed :: iodata()) ->
                         {rand:alg_handler(crypto_prng1), rand_plugin_prng1_state()}.

Create and seed a generator for rand with specified algorithm.

Create a state object (generator) for random number generation, which when used by the rand functions produce cryptographically unpredictable random numbers, that can be reproduced by re-using the same Seed.

See rand:seed_s/1, and for example rand:uniform_s/2, and compare to rand_seed_alg/1.

The state objects created by this function has cached data so they use much more memory than the generators in the rand module.

With Alg = crypto_aes

The Xoroshiro928 generator from the rand module is used as a counter. The generator's state is scrambled through AES-256 to create a 58-bit pseudo random value. This gives a long period (2^928 - 1).

The result should be statistically completely unpredictable random values, since the scrambling is cryptographically strong and the period is extremely long. But the generated numbers are not to be regarded as cryptographically strong since there is no re-keying schedule, and since the sequence is repeated for the same seed.

If you need cryptographically strong random numbers use rand_seed_alg_s/1 with Alg =:= crypto or Alg =:= crypto_cache.

If you need to be able to repeat the sequence use this function with Alg =:= crypto_aes (or Alg =:= crypto_prng1, below).

If you do not need the statistical quality of these generators, there are faster generators in the rand module. The amortized speed of this generator is about 3 times slower than the rand module's default algorithm.

Example

1> S0 = crypto:rand_seed_alg_s(crypto_aes, "my seed").
2> %% 1..42
   {IntegerValue, S1} = rand:uniform_s(42, S0).
3> %% [0.0, 1.0)
   {FloatValue, S2} = rand:uniform_s(S1).
4> {IntegerValue,FloatValue}.
{9,0.7624867055217882}
5> S3 = crypto:rand_seed_alg_s(crypto_aes, "my seed").
6> %% Same values
   {IntegerValue, S4} = rand:uniform_s(42, S3).
7> %% again
   {FloatValue, S5} = rand:uniform_s(S4).

Thanks to the used generator the state object supports the rand:jump/0,1 function with distance 2^512.

Numbers are generated in batches and for speed reasons cached in the generator's state. The cache size can be changed from its default value using the crypto app's configuration parameter rand_cache_size.

Generating bytes, see rand:bytes_s/2, is done from the cached numbers, which limits the performance as for generating numbers. Alg = crypto, is faster, for larger numbers of bytes significantly faster, but cannot be used to reproduce a sequence. Another alternative is Alg = crypto_prng1 that follows here.

With Alg = crypto_prng1 Since OTP @OTP-19882@.

The created generator uses a stream cipher to encrypt data blocks of zeros, which effectively results in the stream cipher's key stream as binary data. The binary data is cached in the generator's state to achieve good amortized speed. From the cached data 58 bit numbers are extracted, to facilitate fast operations in the rand module. The cache size can be changed from its default value using the crypto app's configuration parameter rand_cache_size.

This generator also implements extracting bytes efficiently through rand:bytes_s/2.

The key stream from a stream cipher is cryptographically unpredictable, which should result in statistically completely unpredictable random values, but the generated numbers are not to be regarded as cryptographically strong since there is no re-keying schedule, and since the sequence is repeated for the same seed.

For generating numbers, this generator is about 2 times slower than the default PRNG in the rand module. For generating bytes, it is significantly faster, for any number of bytes. Compared to Alg = crypto, this generator has much less overhead, so for small numbers of bytes it is much faster. Break-even is a bit above the cache size, and over that Alg = crypto is faster, but cannot be used to reproduce a sequence.

Example

1> S0 = crypto:rand_seed_alg_s(crypto_prng1, "my seed").
2> %% 1..42
   {IntegerValue, S1} = rand:uniform_s(42, S0).
3> {Bytes, S2} = rand:bytes_s(7, S1).
4> {IntegerValue,Bytes}.
{20,<<52,185,212,38,248,228,127>>}
5> S3 = crypto:rand_seed_alg_s(crypto_prng1, "my seed").
6> %% Same values
   {IntegerValue, S4} = rand:uniform_s(42, S3).
7> %% again
   {Bytes, S5} = rand:bytes_s(7, S4).

The generator's state contains a crypto_state/0 which refers to the same encryption state even when copied, and the generator's state contains cached random data. It is therefore a bad idea to copy the state in an attempt to fork into multiple generators. The forked generators will produce the same numbers until their caches are empty, and then refill their caches with different sections of the keystream. This is probably never useful.

The created initial state, however, can be copied and exported, as descrided for rand:export_seed_s/1 and rand:seed_s/1, since the crypto_state/0 is not created until the first random value is generated. An exported subsequent generator state cannot be passed intact through Erlang's external term format, and rand_seed_alg_s/1 will fail for an exported state of this generator that is not an initial state.

rand:jump/1 is implemented for this generator, but also only for its initial state. A jump, for this generator, is implemented by incrementing the cipher's IV to create a distinct keystream. This is not much different from using different seed values, but avoids a call to the hash function that is used when seeding.

Example

1> Sa0 = crypto:rand_seed_alg_s(crypto_prng1, "my seed").
2> Sb0 = rand:jump(Sa0).
3> {BytesA, Sa1} = rand:bytes_s(7, Sa0).
4> {BytesB, Sb1} = rand:bytes_s(7, Sb0).
5> BytesA.
<<77,185,41,162,118,82,190>>
6> BytesB.
<<160,61,224,29,177,30,68>>
7> SA0 = crypto:rand_seed_alg_s(crypto_prng1, "my seed").
8> SB0 = rand:jump(SA0).
%% Same values again
9> {BytesA, SA1} = rand:bytes_s(7, SA0).
10> {BytesB, SB1} = rand:bytes_s(7, SB0).

Algorithm details

The Seed is hashed with SHA-384 to create a Key and IV for AES-256 that is run in CTR mode over blocks of zero data.

rand_seed_s()

(since OTP 20.0)

-spec rand_seed_s() -> {rand:alg_handler(crypto), rand_plugin_state()}.

Create a generator for rand.

Create a state object (generator) for random number generation, which when used by the rand functions produce cryptographically strong random numbers (based on OpenSSL's BN_rand_range function). See rand:seed_s/1, and for example rand:uniform_s/2.

This generator also implements generating bytes efficiently (based on OpenSSL's RAND_bytes function). See rand:bytes_s/2 and strong_rand_bytes/1. Since OTP @OTP-19882@.

Example

S0 = crypto:rand_seed_s(),
{RandomInteger, S1} = rand:uniform_s(1000, S0).

May cause the rand functions using this state object to raise the exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

Note

The state returned from this function cannot be used to get a reproducible random sequence as from the other rand functions, since that would not be cryptographically safe.

The only supported usage is to generate one distinct random sequence.

Random API

rand_seed(Seed)

(since OTP 17.0)

-spec rand_seed(binary()) -> ok.

Mixes in the bytes of the given binary into the internal state of OpenSSL's random number generator.

This calls the RAND_seed function from OpenSSL. Only use this if the system you are running on does not have enough "randomness" built in. Normally this is when strong_rand_bytes/1 or a generator from rand_seed_alg_s/1 raises error:low_entropy.

rand_uniform/2

This function is deprecated. crypto:rand_uniform/2 is deprecated; use strong_rand_range/1 instead.

-spec rand_uniform(crypto_integer(), crypto_integer()) -> crypto_integer().

Generate a random integer number.

The interval is From =< N < To. Uses the crypto library pseudo-random number generator. To must be larger than From.

Note

This function is deprecated because it originally used the OpenSSL method BN_pseudo_rand_range that was not cryptographically strong and could not run out of entropy. That behaviour changed in OpenSSL and this function cannot be fixed without making it raise error:low_entropy, which is not backwards compatible.

Instead, use strong_rand_range(To - From) + From

Be aware of the possible error:low_entropy exception.

strong_rand_bytes(N)

(since OTP R14B03)

-spec strong_rand_bytes(N :: non_neg_integer()) -> binary().

Generate bytes with randomly uniform values 0..255.

Returns the result in a binary with N bytes.

Uses a cryptographically secure PRNG seeded and periodically mixed with operating system provided entropy. By default this is the RAND_bytes method from OpenSSL.

May raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

strong_rand_range/1

(since OTP 28.3)

-spec strong_rand_range(Range :: pos_integer()) -> N :: non_neg_integer();
                       (Range :: binary()) -> N :: binary().

Generate a random integer in a specified range.

The returned random integer is in the interval is 0 =< N < Range.

Uses the crypto library random number generator BN_rand_range.

If the Range argument is a pos_integer/0 the return value is a non_neg_integer/0. If the Range argument is a positive integer in a binary/0, the return value is a non-negative integer in a binary/0.

May raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

Sign/Verify API

sign(Algorithm, DigestType, Msg, Key)

(since OTP R16B01)

-spec sign(Algorithm, DigestType, Msg, Key) -> Signature
              when
                  Algorithm :: pk_sign_verify_algs(),
                  DigestType :: rsa_digest_type() | dss_digest_type() | ecdsa_digest_type() | none,
                  Msg :: iodata() | {digest, iodata()},
                  Key ::
                      rsa_private() |
                      dss_private() |
                      [ecdsa_private() | ecdsa_params()] |
                      [eddsa_private() | eddsa_params()] |
                      mldsa_private() |
                      slh_dsa_private() |
                      engine_key_ref(),
                  Signature :: binary().

Equivalent to sign/5.

sign(Algorithm, DigestType, Msg, Key, Options)

(since OTP 20.1)

-spec sign(Algorithm, DigestType, Msg, Key, Options) -> Signature
              when
                  Algorithm :: pk_sign_verify_algs(),
                  DigestType :: rsa_digest_type() | dss_digest_type() | ecdsa_digest_type() | none,
                  Msg :: iodata() | {digest, iodata()},
                  Key ::
                      rsa_private() |
                      dss_private() |
                      [ecdsa_private() | ecdsa_params()] |
                      [eddsa_private() | eddsa_params()] |
                      mldsa_private() |
                      slh_dsa_private() |
                      engine_key_ref(),
                  Options :: pk_sign_verify_opts(),
                  Signature :: binary().

Create a digital signature.

The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).

Algorithm dss can only be used together with digest type sha.

Uses the 3-tuple style for error handling.

See also public_key:sign/3.

verify(Algorithm, DigestType, Msg, Signature, Key)

(since OTP R16B01)

-spec verify(Algorithm, DigestType, Msg, Signature, Key) -> Result
                when
                    Algorithm :: pk_sign_verify_algs(),
                    DigestType :: rsa_digest_type() | dss_digest_type() | ecdsa_digest_type() | none,
                    Msg :: iodata() | {digest, iodata()},
                    Signature :: binary(),
                    Key ::
                        rsa_public() |
                        dss_public() |
                        [ecdsa_public() | ecdsa_params()] |
                        [eddsa_public() | eddsa_params()] |
                        mldsa_public() |
                        slh_dsa_public() |
                        engine_key_ref(),
                    Result :: boolean().

Equivalent to verify/6.

verify(Algorithm, DigestType, Msg, Signature, Key, Options)

(since OTP 20.1)

-spec verify(Algorithm, DigestType, Msg, Signature, Key, Options) -> Result
                when
                    Algorithm :: pk_sign_verify_algs(),
                    DigestType :: rsa_digest_type() | dss_digest_type() | ecdsa_digest_type() | none,
                    Msg :: iodata() | {digest, iodata()},
                    Signature :: binary(),
                    Key ::
                        rsa_public() |
                        dss_public() |
                        [ecdsa_public() | ecdsa_params()] |
                        [eddsa_public() | eddsa_params()] |
                        mldsa_public() |
                        slh_dsa_public() |
                        engine_key_ref(),
                    Options :: pk_sign_verify_opts(),
                    Result :: boolean().

Verify a digital signature.

The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).

Algorithm dss can only be used together with digest type sha.

Uses the 3-tuple style for error handling.

See also public_key:verify/4.

Utility Functions

bytes_to_integer(Bin)

(since OTP R16B01)

-spec bytes_to_integer(binary()) -> integer().

Convert binary representation, of an integer, to an Erlang integer.

cipher_info(Type)

(since OTP 22.0)

-spec cipher_info(Type) -> Result
                     when
                         Type :: cipher(),
                         Result ::
                             #{key_length := integer(),
                               iv_length := integer(),
                               block_size := integer(),
                               mode := CipherModes,
                               type := undefined | integer(),
                               prop_aead := boolean()},
                         CipherModes ::
                             undefined | cbc_mode | ccm_mode | cfb_mode | ctr_mode | ecb_mode |
                             gcm_mode | ige_mode | ocb_mode | ofb_mode | wrap_mode | xts_mode.

Get information about a cipher algorithm.

Returns a map with information about block size, key length, IV length, aead support and possibly other properties of the cipher algorithm in question.

Note

The ciphers aes_cbc, aes_cfb8, aes_cfb128, aes_ctr, aes_ecb, aes_gcm and aes_ccm has no keylength in the Type as opposed to for example aes_128_ctr. They adapt to the length of the key provided in the encrypt and decrypt function. Therefore it is impossible to return a valid keylength in the map.

Always use a Type with an explicit key length,

For a list of supported cipher algorithms, see supports(ciphers).

ec_curve(CurveName)

(since OTP 17.0)

-spec ec_curve(CurveName) -> ExplicitCurve
                  when CurveName :: ec_named_curve(), ExplicitCurve :: ec_explicit_curve().

Return the defining parameters of a elliptic curve.

ec_curves()

(since OTP 17.0)

-spec ec_curves() -> [EllipticCurve]
                   when EllipticCurve :: ec_named_curve() | edwards_curve_dh() | edwards_curve_ed().

Return all supported named elliptic curves.

exor(Bin1, Bin2)

-spec exor(iodata(), iodata()) -> binary().

Perform bit-wise XOR (exclusive or) on the data supplied.

The two byte sequences must be of equal length.

hash_equals(BinA, BinB)

(since OTP 25.0)

-spec hash_equals(BinA, BinB) -> Result when BinA :: binary(), BinB :: binary(), Result :: boolean().

Compare two binaries in constant time, such as results of HMAC computations.

Returns true if the binaries are identical, false if they are of the same length but not identical. The function raises an error:badarg exception if the binaries are of different size.

hash_info(Type)

(since OTP 22.0)

-spec hash_info(Type) -> Result
                   when
                       Type :: hash_algorithm(),
                       Result :: #{size := integer(), block_size := integer(), type := integer()}.

Get information about a hash algorithm.

Returns a map with information about block_size, size and possibly other properties of the hash algorithm in question.

For a list of supported hash algorithms, see supports(hashs).

info()

(since OTP 24.2)

-spec info() ->
              #{compile_type := normal | debug | valgrind | asan,
                cryptolib_version_compiled := string() | undefined,
                cryptolib_version_linked := string(),
                link_type := dynamic | static,
                otp_crypto_version := string(),
                fips_provider_available => boolean(),
                fips_provider_buildinfo => string()}.

Get information about crypto and the OpenSSL backend.

Returns a map with information about the compilation and linking of crypto.

Example:

 1> crypto:info().
 #{compile_type => normal,
   cryptolib_version_compiled => "OpenSSL 3.0.0 7 sep 2021",
   cryptolib_version_linked => "OpenSSL 3.0.0 7 sep 2021",
   link_type => dynamic,
   otp_crypto_version => "5.0.2",
   fips_provider_available => true,
   fips_provider_buildinfo => "3.0.0"}
 2>

More association types than documented may be present in the map. Some of the associations (like fips) may be absent if not supported.

info_fips()

(since OTP 20.0)

-spec info_fips() -> not_supported | not_enabled | enabled.

Get information about the operating status of FIPS.

Returns the FIPS operating status of crypto and the underlying libcrypto library. If crypto was built with FIPS support this can be either enabled (when running in FIPS mode) or not_enabled. For other builds this value is always not_supported.

See configuration parameter fips_mode about how to enable FIPS mode.

Warning

In FIPS mode all non-FIPS compliant algorithms are disabled and raise exception error:notsup. Check supports(ciphers) that in FIPS mode returns the restricted list of available algorithms.

info_lib()

-spec info_lib() -> [{Name, VerNum, VerStr}]
                  when Name :: binary(), VerNum :: integer(), VerStr :: binary().

Get the name and version of the libraries used by crypto.

Name is the name of the library. VerNum is the numeric version according to the library's own versioning scheme. VerStr contains a text variant of the version.

> info_lib().
[{<<"OpenSSL">>,269484095,<<"OpenSSL 1.1.0c  10 Nov 2016"">>}]

Note

From OTP R16 the numeric version represents the version of the OpenSSL header files (openssl/opensslv.h) used when crypto was compiled. The text variant represents the libcrypto library used at runtime. In earlier OTP versions both numeric and text was taken from the library.

mod_pow(N, P, M)

(since OTP R16B01)

-spec mod_pow(N, P, M) -> Result
                 when
                     N :: binary() | integer(),
                     P :: binary() | integer(),
                     M :: binary() | integer(),
                     Result :: binary() | error.

Compute the function N^P mod M.

supports(Type)

(since OTP 22.0)

-spec supports(Type) -> Support
                  when
                      Type :: hashs | ciphers | kems | public_keys | macs | curves | rsa_opts,
                      Support :: Hashs | Ciphers | KEMs | PKs | Macs | Curves | RSAopts,
                      Hashs ::
                          [sha1() |
                           sha2() |
                           sha3() |
                           sha3_xof() |
                           blake2() |
                           ripemd160 |
                           compatibility_only_hash()],
                      Ciphers :: [cipher()],
                      KEMs :: [kem()],
                      PKs :: [rsa | dss | ecdsa | dh | ecdh | eddh | ec_gf2m],
                      Macs :: [hmac | cmac | poly1305],
                      Curves :: [ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()],
                      RSAopts :: [rsa_sign_verify_opt() | rsa_opt()].

Get which crypto algorithms that are supported by the underlying libcrypto library.

See hash_info/1 and cipher_info/1 for information about the hash and cipher algorithms.