Erlang R13B01 ssh and crypto module patch of aes128-cbc support on ssh
Kenji Rikitake
kenji.rikitake@REDACTED
Thu Aug 13 12:09:26 CEST 2009
The following patch includes a feature enhancement of Erlang R13B01 ssh
and crypto modules to support aes128-cbc mode on SSH.
BUG FOUND: ssh_transport:unpack/3 causes crypto:aes_cbc_ivec/1 to crash,
by passing a null binary (<<>>), which causes erlang:split_binary/2 to
crash by badarg.
By tracing the exchange between a FreeBSD OpenSSH implementation, I
found a case where the internal variable SshLength in
ssh_transport:unpack/3 goes to zero, which leads to passing a null
binary as an argument to ssh_transport:decrypt_blocks/3 and to
aes_cbc_ivec/1. So I added a case statement to avoid calling the
decrypt_blocks/3 when SshLength = 0.
Patches follow.
Kenji Rikitake
--- lib/ssh/src/ssh_transport.erl.FCS 2009-06-05 21:55:34.000000000 +0900
+++ lib/ssh/src/ssh_transport.erl 2009-08-13 17:42:28.000000000 +0900
@@ -228,8 +228,10 @@
cookie = Random,
kex_algorithms = ["diffie-hellman-group1-sha1"],
server_host_key_algorithms = ["ssh-rsa", "ssh-dss"],
- encryption_algorithms_client_to_server = ["3des-cbc"],
- encryption_algorithms_server_to_client = ["3des-cbc"],
+ %% encryption_algorithms_client_to_server = ["3des-cbc"],
+ %% encryption_algorithms_server_to_client = ["3des-cbc"],
+ encryption_algorithms_client_to_server = ["aes128-cbc","3des-cbc"],
+ encryption_algorithms_server_to_client = ["aes128-cbc","3des-cbc"],
mac_algorithms_client_to_server = ["hmac-sha1"],
mac_algorithms_server_to_client = ["hmac-sha1"],
compression_algorithms_client_to_server = Compression,
@@ -243,8 +245,10 @@
cookie = Random,
kex_algorithms = ["diffie-hellman-group1-sha1"],
server_host_key_algorithms = ["ssh-dss"],
- encryption_algorithms_client_to_server = ["3des-cbc"],
- encryption_algorithms_server_to_client = ["3des-cbc"],
+ %% encryption_algorithms_client_to_server = ["3des-cbc"],
+ %% encryption_algorithms_server_to_client = ["3des-cbc"],
+ encryption_algorithms_client_to_server = ["aes128-cbc","3des-cbc"],
+ encryption_algorithms_server_to_client = ["aes128-cbc","3des-cbc"],
mac_algorithms_client_to_server = ["hmac-sha1"],
mac_algorithms_server_to_client = ["hmac-sha1"],
compression_algorithms_client_to_server = Compression,
@@ -703,6 +707,9 @@
unpack(EncodedSoFar, ReminingLenght, #ssh{recv_mac_size = MacSize} = Ssh0) ->
SshLength = ReminingLenght - MacSize,
+ %%?dbg(?DBG_CRYPTO,
+ %% "unpack: EncodedsoFar=~p SshLength=~p ReminingLenght=~p MacSize=~p ~n",
+ %% [EncodedSoFar, SshLength, ReminingLenght, MacSize]),
{NoMac, Mac, Rest} = case MacSize of
0 ->
<<NoMac0:SshLength/binary,
@@ -714,8 +721,16 @@
Rest0/binary>> = EncodedSoFar,
{NoMac0, Mac0, Rest0}
end,
- {Ssh1, DecData, <<>>} =
- ssh_transport:decrypt_blocks(NoMac, SshLength, Ssh0),
+ %%?dbg(?DBG_CRYPTO, "unpack: NoMac=~p Mac=~p Rest=~p ~n",
+ %% [NoMac, Mac, Rest]),
+ {Ssh1, DecData, <<>>} = case SshLength of
+ 0 ->
+ {Ssh0, <<>>, <<>>};
+ _ ->
+ ssh_transport:decrypt_blocks(NoMac, SshLength, Ssh0)
+ end,
+ %%?dbg(?DBG_CRYPTO, "unpack: Ssh1=~p DecData=~p Rest=~p Mac=~p ~n",
+ %% [Ssh1, DecData, Rest, Mac]),
{Ssh1, DecData, Rest, Mac}.
msg_data(PacketData) ->
@@ -800,6 +815,18 @@
<<K1:8/binary, K2:8/binary, K3:8/binary>> = hash(Ssh, "D", 192),
{ok, Ssh#ssh{encrypt_keys = {K1,K2,K3},
encrypt_block_size = 8,
+ encrypt_ctx = IV}};
+encrypt_init(#ssh{encrypt = 'aes128-cbc', role = client} = Ssh) ->
+ IV = hash(Ssh, "A", 128),
+ <<K:16/binary>> = hash(Ssh, "C", 128),
+ {ok, Ssh#ssh{encrypt_keys = K,
+ encrypt_block_size = 16,
+ encrypt_ctx = IV}};
+encrypt_init(#ssh{encrypt = 'aes128-cbc', role = server} = Ssh) ->
+ IV = hash(Ssh, "B", 128),
+ <<K:16/binary>> = hash(Ssh, "D", 128),
+ {ok, Ssh#ssh{encrypt_keys = K,
+ encrypt_block_size = 16,
encrypt_ctx = IV}}.
encrypt_final(Ssh) ->
@@ -815,10 +842,19 @@
encrypt_keys = {K1,K2,K3},
encrypt_ctx = IV0} = Ssh, Data) ->
%%?dbg(?DBG_CRYPTO, "encrypt: IV=~p K1=~p, K2=~p, K3=~p ~n",
- %% [IV0,K1,K2,K3]),
+ %% [IV0,K1,K2,K3]),
Enc = crypto:des3_cbc_encrypt(K1,K2,K3,IV0,Data),
%%?dbg(?DBG_CRYPTO, "encrypt: ~p -> ~p ~n", [Data, Enc]),
IV = crypto:des_cbc_ivec(Enc),
+ {Ssh#ssh{encrypt_ctx = IV}, Enc};
+encrypt(#ssh{encrypt = 'aes128-cbc',
+ encrypt_keys = K,
+ encrypt_ctx = IV0} = Ssh, Data) ->
+ %%?dbg(?DBG_CRYPTO, "encrypt: IV=~p K=~p ~n",
+ %% [IV0,K]),
+ Enc = crypto:aes_cbc_128_encrypt(K,IV0,Data),
+ %%?dbg(?DBG_CRYPTO, "encrypt: ~p -> ~p ~n", [Data, Enc]),
+ IV = crypto:aes_cbc_ivec(Enc),
{Ssh#ssh{encrypt_ctx = IV}, Enc}.
@@ -840,7 +876,21 @@
hash(Ssh, "C", 192)},
<<K1:8/binary, K2:8/binary, K3:8/binary>> = KD,
{ok, Ssh#ssh{decrypt_keys = {K1, K2, K3}, decrypt_ctx = IV,
- decrypt_block_size = 8}}.
+ decrypt_block_size = 8}};
+
+decrypt_init(#ssh{decrypt = 'aes128-cbc', role = client} = Ssh) ->
+ {IV, KD} = {hash(Ssh, "B", 128),
+ hash(Ssh, "D", 128)},
+ <<K:16/binary>> = KD,
+ {ok, Ssh#ssh{decrypt_keys = K, decrypt_ctx = IV,
+ decrypt_block_size = 16}};
+
+decrypt_init(#ssh{decrypt = 'aes128-cbc', role = server} = Ssh) ->
+ {IV, KD} = {hash(Ssh, "A", 128),
+ hash(Ssh, "C", 128)},
+ <<K:16/binary>> = KD,
+ {ok, Ssh#ssh{decrypt_keys = K, decrypt_ctx = IV,
+ decrypt_block_size = 16}}.
decrypt_final(Ssh) ->
{ok, Ssh#ssh {decrypt = none,
@@ -858,6 +908,14 @@
Dec = crypto:des3_cbc_decrypt(K1,K2,K3,IV0,Data),
%%?dbg(?DBG_CRYPTO, "decrypt: ~p -> ~p ~n", [Data, Dec]),
IV = crypto:des_cbc_ivec(Data),
+ {Ssh#ssh{decrypt_ctx = IV}, Dec};
+decrypt(#ssh{decrypt = 'aes128-cbc', decrypt_keys = Key,
+ decrypt_ctx = IV0} = Ssh, Data) ->
+ %%?dbg(?DBG_CRYPTO, "decrypt: IV=~p Key=~p ~n",
+ %% [IV0,Key]),
+ Dec = crypto:aes_cbc_128_decrypt(Key,IV0,Data),
+ %%?dbg(?DBG_CRYPTO, "decrypt: ~p -> ~p ~n", [Data, Dec]),
+ IV = crypto:aes_cbc_ivec(Data),
{Ssh#ssh{decrypt_ctx = IV}, Dec}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
--- lib/crypto/src/crypto.erl.FCS 2009-03-12 21:28:35.000000000 +0900
+++ lib/crypto/src/crypto.erl 2009-08-13 13:27:09.000000000 +0900
@@ -45,6 +45,7 @@
%% -export([idea_cbc_encrypt/3, idea_cbc_decrypt/3]).
-export([aes_cbc_128_encrypt/3, aes_cbc_128_decrypt/3]).
-export([aes_cbc_256_encrypt/3, aes_cbc_256_decrypt/3]).
+-export([aes_cbc_ivec/1]).
-export([dh_generate_parameters/2, dh_check/1]). %% Testing see below
@@ -469,6 +470,19 @@
control(?AES_CBC_256_DECRYPT, [Key, IVec, Data]).
%%
+%% aes_cbc_ivec(Data) -> binary()
+%%
+%% Returns the IVec to be used in the next iteration of
+%% aes_cbc_*_[encrypt|decrypt].
+%% IVec size: 16 bytes
+%%
+aes_cbc_ivec(Data) when is_binary(Data) ->
+ {_, IVec} = split_binary(Data, size(Data) - 16),
+ IVec;
+aes_cbc_ivec(Data) when is_list(Data) ->
+ aes_cbc_ivec(list_to_binary(Data)).
+
+%%
%% XOR - xor to iolists and return a binary
%% NB doesn't check that they are the same size, just concatenates
%% them and sends them to the driver
-------------- next part --------------
--- lib/ssh/src/ssh_transport.erl.FCS 2009-06-05 21:55:34.000000000 +0900
+++ lib/ssh/src/ssh_transport.erl 2009-08-13 17:42:28.000000000 +0900
@@ -228,8 +228,10 @@
cookie = Random,
kex_algorithms = ["diffie-hellman-group1-sha1"],
server_host_key_algorithms = ["ssh-rsa", "ssh-dss"],
- encryption_algorithms_client_to_server = ["3des-cbc"],
- encryption_algorithms_server_to_client = ["3des-cbc"],
+ %% encryption_algorithms_client_to_server = ["3des-cbc"],
+ %% encryption_algorithms_server_to_client = ["3des-cbc"],
+ encryption_algorithms_client_to_server = ["aes128-cbc","3des-cbc"],
+ encryption_algorithms_server_to_client = ["aes128-cbc","3des-cbc"],
mac_algorithms_client_to_server = ["hmac-sha1"],
mac_algorithms_server_to_client = ["hmac-sha1"],
compression_algorithms_client_to_server = Compression,
@@ -243,8 +245,10 @@
cookie = Random,
kex_algorithms = ["diffie-hellman-group1-sha1"],
server_host_key_algorithms = ["ssh-dss"],
- encryption_algorithms_client_to_server = ["3des-cbc"],
- encryption_algorithms_server_to_client = ["3des-cbc"],
+ %% encryption_algorithms_client_to_server = ["3des-cbc"],
+ %% encryption_algorithms_server_to_client = ["3des-cbc"],
+ encryption_algorithms_client_to_server = ["aes128-cbc","3des-cbc"],
+ encryption_algorithms_server_to_client = ["aes128-cbc","3des-cbc"],
mac_algorithms_client_to_server = ["hmac-sha1"],
mac_algorithms_server_to_client = ["hmac-sha1"],
compression_algorithms_client_to_server = Compression,
@@ -703,6 +707,9 @@
unpack(EncodedSoFar, ReminingLenght, #ssh{recv_mac_size = MacSize} = Ssh0) ->
SshLength = ReminingLenght - MacSize,
+ %%?dbg(?DBG_CRYPTO,
+ %% "unpack: EncodedsoFar=~p SshLength=~p ReminingLenght=~p MacSize=~p ~n",
+ %% [EncodedSoFar, SshLength, ReminingLenght, MacSize]),
{NoMac, Mac, Rest} = case MacSize of
0 ->
<<NoMac0:SshLength/binary,
@@ -714,8 +721,16 @@
Rest0/binary>> = EncodedSoFar,
{NoMac0, Mac0, Rest0}
end,
- {Ssh1, DecData, <<>>} =
- ssh_transport:decrypt_blocks(NoMac, SshLength, Ssh0),
+ %%?dbg(?DBG_CRYPTO, "unpack: NoMac=~p Mac=~p Rest=~p ~n",
+ %% [NoMac, Mac, Rest]),
+ {Ssh1, DecData, <<>>} = case SshLength of
+ 0 ->
+ {Ssh0, <<>>, <<>>};
+ _ ->
+ ssh_transport:decrypt_blocks(NoMac, SshLength, Ssh0)
+ end,
+ %%?dbg(?DBG_CRYPTO, "unpack: Ssh1=~p DecData=~p Rest=~p Mac=~p ~n",
+ %% [Ssh1, DecData, Rest, Mac]),
{Ssh1, DecData, Rest, Mac}.
msg_data(PacketData) ->
@@ -800,6 +815,18 @@
<<K1:8/binary, K2:8/binary, K3:8/binary>> = hash(Ssh, "D", 192),
{ok, Ssh#ssh{encrypt_keys = {K1,K2,K3},
encrypt_block_size = 8,
+ encrypt_ctx = IV}};
+encrypt_init(#ssh{encrypt = 'aes128-cbc', role = client} = Ssh) ->
+ IV = hash(Ssh, "A", 128),
+ <<K:16/binary>> = hash(Ssh, "C", 128),
+ {ok, Ssh#ssh{encrypt_keys = K,
+ encrypt_block_size = 16,
+ encrypt_ctx = IV}};
+encrypt_init(#ssh{encrypt = 'aes128-cbc', role = server} = Ssh) ->
+ IV = hash(Ssh, "B", 128),
+ <<K:16/binary>> = hash(Ssh, "D", 128),
+ {ok, Ssh#ssh{encrypt_keys = K,
+ encrypt_block_size = 16,
encrypt_ctx = IV}}.
encrypt_final(Ssh) ->
@@ -815,10 +842,19 @@
encrypt_keys = {K1,K2,K3},
encrypt_ctx = IV0} = Ssh, Data) ->
%%?dbg(?DBG_CRYPTO, "encrypt: IV=~p K1=~p, K2=~p, K3=~p ~n",
- %% [IV0,K1,K2,K3]),
+ %% [IV0,K1,K2,K3]),
Enc = crypto:des3_cbc_encrypt(K1,K2,K3,IV0,Data),
%%?dbg(?DBG_CRYPTO, "encrypt: ~p -> ~p ~n", [Data, Enc]),
IV = crypto:des_cbc_ivec(Enc),
+ {Ssh#ssh{encrypt_ctx = IV}, Enc};
+encrypt(#ssh{encrypt = 'aes128-cbc',
+ encrypt_keys = K,
+ encrypt_ctx = IV0} = Ssh, Data) ->
+ %%?dbg(?DBG_CRYPTO, "encrypt: IV=~p K=~p ~n",
+ %% [IV0,K]),
+ Enc = crypto:aes_cbc_128_encrypt(K,IV0,Data),
+ %%?dbg(?DBG_CRYPTO, "encrypt: ~p -> ~p ~n", [Data, Enc]),
+ IV = crypto:aes_cbc_ivec(Enc),
{Ssh#ssh{encrypt_ctx = IV}, Enc}.
@@ -840,7 +876,21 @@
hash(Ssh, "C", 192)},
<<K1:8/binary, K2:8/binary, K3:8/binary>> = KD,
{ok, Ssh#ssh{decrypt_keys = {K1, K2, K3}, decrypt_ctx = IV,
- decrypt_block_size = 8}}.
+ decrypt_block_size = 8}};
+
+decrypt_init(#ssh{decrypt = 'aes128-cbc', role = client} = Ssh) ->
+ {IV, KD} = {hash(Ssh, "B", 128),
+ hash(Ssh, "D", 128)},
+ <<K:16/binary>> = KD,
+ {ok, Ssh#ssh{decrypt_keys = K, decrypt_ctx = IV,
+ decrypt_block_size = 16}};
+
+decrypt_init(#ssh{decrypt = 'aes128-cbc', role = server} = Ssh) ->
+ {IV, KD} = {hash(Ssh, "A", 128),
+ hash(Ssh, "C", 128)},
+ <<K:16/binary>> = KD,
+ {ok, Ssh#ssh{decrypt_keys = K, decrypt_ctx = IV,
+ decrypt_block_size = 16}}.
decrypt_final(Ssh) ->
{ok, Ssh#ssh {decrypt = none,
@@ -858,6 +908,14 @@
Dec = crypto:des3_cbc_decrypt(K1,K2,K3,IV0,Data),
%%?dbg(?DBG_CRYPTO, "decrypt: ~p -> ~p ~n", [Data, Dec]),
IV = crypto:des_cbc_ivec(Data),
+ {Ssh#ssh{decrypt_ctx = IV}, Dec};
+decrypt(#ssh{decrypt = 'aes128-cbc', decrypt_keys = Key,
+ decrypt_ctx = IV0} = Ssh, Data) ->
+ %%?dbg(?DBG_CRYPTO, "decrypt: IV=~p Key=~p ~n",
+ %% [IV0,Key]),
+ Dec = crypto:aes_cbc_128_decrypt(Key,IV0,Data),
+ %%?dbg(?DBG_CRYPTO, "decrypt: ~p -> ~p ~n", [Data, Dec]),
+ IV = crypto:aes_cbc_ivec(Data),
{Ssh#ssh{decrypt_ctx = IV}, Dec}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-------------- next part --------------
--- lib/crypto/src/crypto.erl.FCS 2009-03-12 21:28:35.000000000 +0900
+++ lib/crypto/src/crypto.erl 2009-08-13 13:27:09.000000000 +0900
@@ -45,6 +45,7 @@
%% -export([idea_cbc_encrypt/3, idea_cbc_decrypt/3]).
-export([aes_cbc_128_encrypt/3, aes_cbc_128_decrypt/3]).
-export([aes_cbc_256_encrypt/3, aes_cbc_256_decrypt/3]).
+-export([aes_cbc_ivec/1]).
-export([dh_generate_parameters/2, dh_check/1]). %% Testing see below
@@ -469,6 +470,19 @@
control(?AES_CBC_256_DECRYPT, [Key, IVec, Data]).
%%
+%% aes_cbc_ivec(Data) -> binary()
+%%
+%% Returns the IVec to be used in the next iteration of
+%% aes_cbc_*_[encrypt|decrypt].
+%% IVec size: 16 bytes
+%%
+aes_cbc_ivec(Data) when is_binary(Data) ->
+ {_, IVec} = split_binary(Data, size(Data) - 16),
+ IVec;
+aes_cbc_ivec(Data) when is_list(Data) ->
+ aes_cbc_ivec(list_to_binary(Data)).
+
+%%
%% XOR - xor to iolists and return a binary
%% NB doesn't check that they are the same size, just concatenates
%% them and sends them to the driver
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