On Thu, Feb 09, 2006, Dave wrote:

> Hi,
> I am performing an AES encryption with 16 bytes of data with a 128
> bit key, CBC mode, and PKCS5 padding enabled through OpenSSL 0.9.8a.
> When trying to decrypt the data (with different code), I was receiving
> padding errors, so I decrypted the data without padding to take a look
>
> Turns out the pad byte was computed correctly (16), but was only
> applied to the last 8 bytes (maybe the AES block size of 16 is being
> ignored?):
>
> (32) 66, 66, 83, 101, 110, 100, 101, 114, 67, 45, 48, 45, 49, 48, 48,
> 49, -57, 37, 16, -82, 115, -25, 23, 96, 16, 16, 16, 16, 16, 16, 16,
> 16,
>
> this of course, should be:
>
> (32) 66, 66, 83, 101, 110, 100, 101, 114, 67, 45, 48, 45, 49, 48, 48,
> 49, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
>


Well it works OK on the command line:

echo -n 0123456789abcdef | openssl enc -aes-128-cbc -pass pass:hello -nosalt |
openssl enc -aes-128-cbc -d -pass pass:hello -nosalt -nopad | hd
00000000 30 31 32 33 34 35 36 37 38 39 61 62 63 64 65 66 |0123456789abcdef|
00000010 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 |................|
00000020

Steve.
--
Dr Stephen N. Henson. Email, S/MIME and PGP keys: see homepage
OpenSSL project core developer and freelance consultant.
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