[openssl-users] using openssl to validate an external AES program

[Erwann Abalea]

Bonjour,

> Le 9 oct. 2015 à 12:20, karel-de-macil at wanadoo.fr a écrit :
> 
[…]
> Case #1: Encrypting 16 bytes (1 block) using AES-CBC with 128-bit key
> Key : 0x06a9214036b8a15b512e03d534120006
> IV : 0x3dafba429d9eb430b422da802c9fac41
> Plaintext : "Single block msg"
> Ciphertext: 0xe353779c1079aeb82708942dbe77181a
> 
> the command line i launch is the following
> 
> :~/git/aes/openssl$ od -c clear3.txt
> 0000000 S i n g l e b l o c k m s g
> 0000020
> openssl enc -nosalt -aes-128-cbc -in clear3.txt -e -out test.enc -K 06a9214036b8a15b512e03d534120006 -iv 3dafba429d9eb430b422da802c9fac41
> 
> :~/git/aes/openssl$ od -x test.enc
> 0000000 53e3 9c77 7910 b8ae 0827 2d94 77be 1a18
> 0000020 7cb9 5e82 781c 4651 2d54 6939 bc41 5de5
> 0000040
> 
> The first 16 bit are the answer given but what are the 16 following one ?

Padding, so the decryption process knows how many useful octets were encrypted. In your case, since the block is full, padding adds another block.

> 
> bellow that, my own program is AES-128 , not aes-128-cbc but for a msg of 16 bit only and a nul iv there should be no difference for what i understand.
> 
> but when i use the following number found here :
> 
> http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
> 
> PLAINTEXT: 00112233445566778899aabbccddeeff
> KEY:
> 000102030405060708090a0b0c0d0e0f
> 
> round[10].output 69c4e0d86a7b0430d8cdb78070b4c55a
> 
> i get the following
> 
> :~/git/aes/openssl$ od -x clear2.txt
> 0000000 1100 3322 5544 7766 9988 bbaa ddcc ffee
> 0000020
> :~/git/aes/openssl$ openssl enc -nosalt -in clear2.txt -out encrypted.dat -e -aes-128-cbc -k 000102030405060708090a0b0c0d0e0f -iv 00000000000000000000000000000000

-k is not the same as -K.


Cordialement,
Erwann Abalea