Output size after AES256 encryption?

[chakriv]

Hello,

I have to encrypt the data with AES256 encryption algorithm.
If my input data is 256 bytes after the encryption it will 256bytes of data??

Thanks in advance.

[paulej]

Not with AES Crypt. The program will put a header on the front of it to identify that it's an AES Crypt encrypted file. It will also insert a session key that is encrypted in the front. There are also HMAC values inserted to ensure message integrity. There could be as many as 292 octets added, I think. It's a sizeable footprint. However, there are some pieces of the header that could be removed. You would need to modify the source code, but all of the "Extension identifier" information could be removed. You can see the format of the files documented here:
http://www.aescrypt.com/aes_file_format.html