Hi Matthew,

Awesome, thanks and sorry for contacting the wrong list!

Since then, I found the answer to the 14 bytes question:
https://hg.mozilla.org/projects/nss/rev/fc636973ad06392d11597620b602779b4af312f6#l6.49
Basically the DER encoding is used instead for compatibility with a bugged
implementation.

I tried prepending b'\x04\x0e' to DER-encode the IV. However, the value I
get makes no sense (and even has an incorrect padding according to pkcs7
<https://tools.ietf.org/html/rfc2315>).


Best,

Louis

Le ven. 27 mars 2020 à 19:57, Matthew N. <ma...@mozilla.com> a écrit :

> Hi Louis,
>
> The dev-tech-crypto mailing list I'm redirecting this to should be able to
> get you an answer.
>
> Thanks,
> MattN
>
>
> On Fri, Mar 27, 2020 at 8:51 AM Louis Abraham <louis.abra...@yahoo.fr>
> wrote:
>
>> Hi,
>>
>> I'm the main developer of https://github.com/louisabraham/ffpass
>> We are currently trying to accommodate the (not so) recent cryptographic
>> changes in key4.db.
>>
>> If I understand correctly, key4.db contains a table metadata. The value
>> item2 defines a cryptographic algorithm in the DER format.
>>
>> In the latest version of Firefox, this algorithm is PBES2, using
>> aes256-CBC as the encryption algorithm.
>>
>> I'm facing a little problem when trying to execute aes256-CBC because the
>> IV size is only 14 bytes (56 bits) instead of the 64 bits defined in the
>> spec.
>>
>> Could you please help me to understand?
>>
>> Best,
>> Louis
>>
>
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