Other Constants

OPENSSL_RAW_DATA (bool)
If OPENSSL_RAW_DATA is set in the openssl_encrypt() or openssl_decrypt(), the returned data is returned as-is. When it is not specified, Base64 encoded data is returned to the caller.
OPENSSL_ZERO_PADDING (bool)
By default encryption operations are padded using standard block padding and the padding is checked and removed when decrypting. If OPENSSL_ZERO_PADDING is set in the openssl_encrypt() or openssl_decrypt() options then no padding is performed, the total amount of data encrypted or decrypted must then be a multiple of the block size or an error will occur.
OPENSSL_ENCODING_SMIME (int)
Indicates that encoding is S/MIME.
OPENSSL_ENCODING_DER (int)
Indicates that encoding is DER (Distinguished Encoding Rules).
OPENSSL_ENCODING_PEM (int)
Indicates that encoding is PEM (Privacy-Enhanced Mail).