On Wed, November 21, 2007 2:39 pm, Lidia Fernández wrote:
> I have to encrypt a file in c with openssl and then i have to decrypt in
> Java.
>
> In Java i use to decrypt the algorithm
>
> Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
>
> With OpenSSL i use
>
> openssl enc -a -des-ecb -in file -out file.enc -pass pass:abcdefgh
>
> but i have an error message in Java that say
>
> javax.crypto.BadPaddingException: Given final block not properly padded
>
>
> What padding does OpenSSL use??? How can i specify the padding??
Having just recently been grappling with this, you need to make sure, in
your OpenSSL code, that the EVP_EncryptFinal_ex() function is being
executed correctly on the last block of data.
Left to the defaults, EVP_EncryptFinal_ex worries about the padding, you
do not need to do anything.
One problem that I did encounter was issues with the length of the
encrypted block. In my code, I was encrypting the block, and then base64
encoding the result. I then un-base64-encoded the result, and then applied
the decryption to reverse the process. The problem was in my case that the
length I was using to decrypt the code was the length returned by the
base64 decoder, which was adding 1 to the real length to be a terminating
0 character.
OpenSSL then complained that it could not decrypt the final block.
In other words, double check your lengths and make sure they are correct
all the way through.
Regards,
Graham
--
______________________________________________________________________
OpenSSL Project http://www.openssl.org
User Support Mailing List openssl-users@openssl.org
Automated List Manager [EMAIL PROTECTED]
