openssl_verify

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

openssl_verify — Verify signature

Description

openssl_verify(
    string $data,
    string $signature,
    OpenSSLAsymmetricKey|OpenSSLCertificate|array|string $public_key,
    string|int $algorithm = OPENSSL_ALGO_SHA1,
    int $padding = 0
): int|false

openssl_verify() verifies that the signature is correct for the specified data using the public key associated with public_key. This must be the public key corresponding to the private key used for signing.

Parameters

data

The string of data used to generate the signature previously

signature

A raw binary string, generated by openssl_sign() or similar means

public_key

OpenSSLAsymmetricKey - a key, returned by openssl_get_publickey()

string - a PEM formatted key (e.g. -----BEGIN PUBLIC KEY----- MIIBCgK...)

algorithm

int - one of these Signature Algorithms.

string - a valid string returned by openssl_get_md_methods() example, "sha1WithRSAEncryption" or "sha512".

padding
RSA PSS padding to use.

Return Values

Returns 1 if the signature is correct, 0 if it is incorrect, and -1 or false on error.

Changelog

VersionDescription
8.5.0The optional parameter padding has been added.
8.0.0public_key accepts an OpenSSLAsymmetricKey or OpenSSLCertificate instance now; previously, a resource of type OpenSSL key or OpenSSL X.509 was accepted.

Examples

Example #1 openssl_verify() example

<?php
// $data and $signature are assumed to contain the data and the signature

// fetch public key from certificate and ready it
$pubkeyid = openssl_pkey_get_public("file://src/openssl-0.9.6/demos/sign/cert.pem");

// state whether signature is okay or not
$ok = openssl_verify($data, $signature, $pubkeyid);
if ($ok == 1) {
echo "good";
} elseif ($ok == 0) {
echo "bad";
} else {
echo "ugly, error checking signature";
}
// free the key from memory
openssl_free_key($pubkeyid);
?>

Example #2 openssl_verify() example

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

//create new private and public key
$private_key_res = openssl_pkey_new(array(
"private_key_bits" => 2048,
"private_key_type" => OPENSSL_KEYTYPE_RSA,
));
$details = openssl_pkey_get_details($private_key_res);
$public_key_res = openssl_pkey_get_public($details['key']);

//create signature
openssl_sign($data, $signature, $private_key_res, "sha256WithRSAEncryption");

//verify signature
$ok = openssl_verify($data, $signature, $public_key_res, OPENSSL_ALGO_SHA256);
if ($ok == 1) {
echo "valid";
} elseif ($ok == 0) {
echo "invalid";
} else {
echo "error: ".openssl_error_string();
}
?>

See Also