OpenSSL Functions
PHP Manual

openssl_verify

Verify signature

Description

int openssl_verify ( string $data , string $signature , mixed $pub_key_id [, mixed $signature_alg = OPENSSL_ALGO_SHA1 ] )

openssl_verify verifies that the signature is correct for the specified data using the public key associated with pub_key_id. 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

pub_key_id

resource - a key, returned by openssl_get_publickey

string - a PEM formatted key, example, "-----BEGIN PUBLIC KEY----- MIIBCgK..."

signature_alg

int - one of these Signature Algorithms.

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

Return Values

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

Changelog

Version Description
5.2.0 The signature_alg parameter was added.

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, "sha1WithRSAEncryption");

//verify signature
$ok = openssl_verify($data, $signature, $public_key_res, OPENSSL_ALGO_SHA1);
if ($ok == 1) {
    echo "valid";
} elseif ($ok == 0) {
    echo "invalid";
} else {
    echo "error: ".openssl_error_string();
}
?>

See Also

  • openssl_sign