openssl_sign

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

Generate signature

bool openssl_sign ( string $data, string &$signature, mixed $priv_key_id [, mixed $signature_alg = OPENSSL_ALGO_SHA1 ] )

openssl_sign() computes a signature for the specified data by generating a cryptographic digital signature using the private key associated with priv_key_id. Note that the data itself is not encrypted.

Parameters:

data

The string of data you wish to sign

signature

If the call was successful the signature is returned in signature.

priv_key_id

resource - a key, returned by openssl_get_privatekey()

string - a PEM formatted key

signature_alg

int - one of these Signature Algorithms.

string - a valid string returned by openssl_get_md_methods() example, "sha256WithRSAEncryption" or "sha384".

Returns:

Returns TRUE on success or FALSE on failure.

Examples:

openssl_sign() example

<?php
// $data is assumed to contain the data to be signed

// fetch private key from file and ready it
$pkeyid = openssl_pkey_get_private("file://src/openssl-0.9.6/demos/sign/key.pem");

// compute signature
openssl_sign($data, $signature, $pkeyid);

// free the key from memory
openssl_free_key($pkeyid);
?>

openssl_sign() example

<?php
//data you want to sign
$data = 'my data';

//create new private and public key
$new_key_pair = openssl_pkey_new(array(
    "private_key_bits" => 2048,
    "private_key_type" => OPENSSL_KEYTYPE_RSA,
));
openssl_pkey_export($new_key_pair, $private_key_pem);

$details = openssl_pkey_get_details($new_key_pair);
$public_key_pem = $details['key'];

//create signature
openssl_sign($data, $signature, $private_key_pem, OPENSSL_ALGO_SHA256);

//save for later
file_put_contents('private_key.pem', $private_key_pem);
file_put_contents('public_key.pem', $public_key_pem);
file_put_contents('signature.dat', $signature);

//verify signature
$r = openssl_verify($data, $signature, $public_key_pem, "sha256WithRSAEncryption");
var_dump($r);
?>