Encrypts "plaintext" using the block cipher specified by "ciphername", placing the encrypted data into "encrypted".
Syntax
crypto_evp_encrypt( ciphername, key, iv, plaintext, encrypted var )
returns 1 on success, 0 on failure
ciphername = The OpenSSL identifier of the cipher, such as "bf-cbc" or "des-ede3-cbc".
key = The encryption key. Must be exactly the number of bytes required by the cipher, as returned by crypto_cipher_key_length.
iv = An initialization vector, if required by the cipher. Must be exactly the number of bytes required by the cipher, as returned by crypto_cipher_iv_length.