Thanks for the comments. > If you are implementing HMAC, perhaps for PBKDF2 (which does > that prehash-if-too-long), I hope you mean the code does... Yes it does. The man page (the one online from OpenSSL project - SHA256.html) gives a description using SHA1() which computes a message digest. Being generally new to OpenSSL at that level, what is then the difference between using, say, SHA1() vs. using SHA1_Init, SHA1_Update and SHA1_Final ? Is it only that the latter allows for continuously add data until _Final is called ? -- View this message in context: http://openssl.6102.n7.nabble.com/SHA256-to-EVP-tp57774p57791.html Sent from the OpenSSL - User mailing list archive at Nabble.com.