[erlang-questions] blowfish cbc mode decrypt

[Dmitry Kolesnikov]

Hello,

I would double check that you are
 * using same key on both side
 * IV is properly serialized and de-serialize to packet frame

BTW, What is the size of Rest? and Can you share minimal viable example of encryption?

- Dmitry

> On Nov 9, 2015, at 11:38 AM, Bogdan Andu <bog495@REDACTED> wrote:
> 
> 
> hi,
> 
> I really need some pointers about this issue
> 
> as i tried all kinds of combinations of IV and body
> to be decrypted.
> 
> Am i missing something or there is a bug in cipher
> blowfish_cbc ?
> 
> 
> 
> On Thu, Nov 5, 2015 at 3:51 PM, Bogdan Andu <bog495@REDACTED> wrote:
>  Data to be decrypted (arrived on socket, etc) is:
> <<IvSpec:8/binary, IV:8/binary, Rest/binary>> = EncryptedData
> 
> IV is ectracted form the 8-byte prepanded value preceding 
> IvSpec which has the value RandomIV.
> 
> decryption of Rest should be initialized with IV.
> 
> 
> On Thu, Nov 5, 2015 at 3:38 PM, Radoslaw Gruchalski <radek@REDACTED> wrote:
> You say your data is:
> 
> <<IvSpec>> == <<RandomIv>>
> 
> But you read:
> 
> Is your data <<IvSpec:8/binary, IV:8/binary, Rest/binary>>
> 
> Should it not be just:
> 
> <<IV:8/binary, Rest/binary>>
> 
> ?
> 
> Sent from Outlook
> 
> _____________________________
> From: Bogdan Andu <bog495@REDACTED>
> Sent: Thursday, November 5, 2015 2:26 p.m.
> Subject: [erlang-questions] blowfish cbc mode decrypt
> To: Erlang <erlang-questions@REDACTED>
> 
> 
> 
> Hi, 
> 
> I have a stream of data called EncryptedData (with randomiv header specification). 
> I want to decrypt  using: 
> crypto:block_decrypt(blowfish_cbc, hexstr2bin(Key), IV, Rest). 
> 
> where: 
> 
> EncryptedData is formatted as follows: 
> <<IvSpec:8/binary, IV:8/binary, Rest/binary>> 
> 
> IvSpec == <<"RandomIV">> 
> 
> However the decryption does not works and garbage is generated 
> (the function  ) . 
> 
> What could be done given the fact that IV is an 8-byte quantity 
> the Key is formatted according to crypto test suites and is 16 bytes long 
> 
> Am I missing something? 
> 
> Thanks, 
> 
> Bogdan 
> 
> 
> 
> 
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