Decrypts "plaintext" using the block cipher specified by "ciphername", placing the decrypted data into "plaintext".
crypto_evp_decrypt( ciphername, key, iv, encrypted, plaintext var )
Return 1 on success, 0 on failure.
- ciphername = The OpenSSL identifier of the cipher, such as "bf-cbc" or "des-ede3-cbc".
- key = The key used for encryption.
- iv = The initialization vector used for encryption. returned by crypto_cipher_iv_length().
- encrypted = The ciphertext to be decrypted
- plaintext = [output] Receives the plaintext