Hy guys, another problem about openssl:
I have this command:
openssl enc -aes-192-cbc -pbkdf2 -e -in <infile> -out <outfile> -pass pass:password
Now i have only the ciphertext of this command and i know the password and then i know also the salt that is the first 8 bytes of the ciphertext after the string "Salted__". I know also that openssl as default parameter take 1000 iteration count and sha256 as a digest. My problem is: how i can go back to the derived key and derived iv from c language?
My code is this but it not return the right values:
void decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *plaintext, const char *password, unsigned char* salt){
EVP_CIPHER_CTX *ctx;
int len;
int plaintext_len;
//unsigned char* key = "EF04020D6979FC09CC1859A2BFB832FFFCF57C64BA61F682"; right value
//unsigned char* iv = "722EDDC813763C9AAB96A0A6885CE1DB"; right value
unsigned char key[24], iv[16];
int i;
PKCS5_PBKDF2_HMAC(password, strlen(password), (unsigned char*)salt, strlen(salt), 1000, EVP_sha256(), 16, key);
EVP_BytesToKey(EVP_aes_192_cbc(), EVP_sha256(), (unsigned char*)salt, (unsigned char*)password, strlen(password), 1000, key+16, iv);
printf("Key: "); for(i=0; i < 24; ++i){ printf("%02x", key[i]); } printf("\n");
printf("IV: "); for(i=0; i < 16; ++i){ printf("%02x", iv[i]); } printf("\n\n");
//Create and initialise the context
if(!(ctx = EVP_CIPHER_CTX_new()))
handleErrors();
//Initialise the decryption operation. IMPORTANT - ensure you use a key
//and IV size appropriate for your cipher
if(1 != EVP_DecryptInit_ex(ctx, EVP_aes_192_cbc(), NULL, key, iv))
handleErrors();
//Provide the message to be decrypted, and obtain the plaintext output.
//EVP_DecryptUpdate can be called multiple times if necessary.
if(1 != EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len))
handleErrors();
plaintext_len = len;
//Finalise the decryption. Further plaintext bytes may be written at
//this stage.
if(1 != EVP_DecryptFinal_ex(ctx, plaintext + len, &len))
handleErrors();
plaintext_len += len;
//Clean up
EVP_CIPHER_CTX_free(ctx);
}
The right values are commented and i take it from the terminal.... but my c code don't return that values. I think this depends by the fact that i don't translate well the -pbkdf2 derivation key...Help me please
