openssl_private_encrypt Encrypts data with private key boolopenssl_private_encrypt stringdata stringcrypted mixedkey intpadding openssl_private_encrypt encrypts data with private key and stores the result into crypted. Encrypted data can be decrypted via openssl_public_decrypt. padding defaults to OPENSSL_PKCS1_PADDING, but can also be OPENSSL_NO_PADDING. &return.success; This function can be used e.g. to sign data (or its hash) to prove that it is not written by someone else. See also openssl_public_decrypt and openssl_public_encrypt.