The EVP API is documented here: https://www.openssl.org/docs/crypto/EVP_EncryptInit.html#
There is some example code there too. It doesn't use AES or CTR, but the principle is the same. Just replace EVP_bf_cbc() with EVP_aes_256_ctr(), and ensure you use an appropriately sized key and IV. Matt On 14 January 2013 20:44, Rohit Bansal <banr...@gmail.com> wrote: > Thanks Matt. Is there a sample code i can look into? > > In my case the key is unique across different messages, so having same IV > across messages should not lead me into problem > > Thanks, > Rohit Bansal > > > On Mon, Jan 14, 2013 at 12:22 PM, Matt Caswell <fr...@baggins.org> wrote: > >> Yes, you can use CTR mode for AES-256: use the EVP interface with the >> EVP_CIPHER of EVP_aes_256_ctr(). >> >> However it is a fundamental requirement of CTR mode that the IV must be >> unique across messages. If you reuse the IV then your messages can be >> broken quite trivially. Therefore, if by a fixed IV, you mean that it is >> fixed across multiple messages then CTR mode is not suitable for you. >> >> Matt >> >> >> On 14 January 2013 19:25, Rohit Bansal <banr...@gmail.com> wrote: >> >>> Hi, >>> >>> Can somebody help me if CTR mode is supported in openssl for AES-256 >>> encryption? >>> >>> I dont want to use CBC and i have a fixed IV. >>> >>> Thanks, >>> Rohit >>> >> >> > > > -- > Rohit Bansal >
