Verifies digital signature of x509 certificate against a public key

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- PHP Manual
- OpenSSL Functions
- Verifies digital signature of x509 certificate against a public key

# openssl_x509_verify

(PHP 7 >= 7.4.0, PHP 8)

openssl_x509_verify — Verifies digital signature of x509 certificate against a public key

### Description

openssl_x509_verify(OpenSSLCertificate|string `$certificate`, OpenSSLAsymmetricKey|OpenSSLCertificate|array|string `$public_key`): int

openssl_x509_verify() verifies that the `certificate` certificate was signed by the private key corresponding to public key `public_key`.

### Parameters

`x509`

  See Key/Certificate parameters for a list of valid values.

`public_key`

  OpenSSLAsymmetricKey - a key, returned by openssl_get_publickey()

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

### Return Values

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

### Changelog

Version | Description
--- | ---
8.0.0 | `certificate` accepts an OpenSSLCertificate instance now; previously, a resource of type `OpenSSL X.509` was accepted.
8.0.0 | `public_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_x509_verify() example

    <?php
    $hostname = "news.php.net";
    $ssloptions = array(
        "capture_peer_cert" => true,
        "capture_peer_cert_chain" => true,
        "allow_self_signed"=> false,
        "CN_match" => $hostname,
        "verify_peer" => true,
        "SNI_enabled" => true,
        "SNI_server_name" => $hostname,
    );

    $ctx = stream_context_create( array("ssl" => $ssloptions) );
    $result = stream_socket_client("ssl://$hostname:443", $errno, $errstr, 30, STREAM_CLIENT_CONNECT, $ctx);
    $cont = stream_context_get_params($result);
    $x509 = $cont["options"]["ssl"]["peer_certificate"];
    $certparsed = openssl_x509_parse($x509);

    foreach($cont["options"]["ssl"]["peer_certificate_chain"] as $chaincert)
    {
        $chainparsed = openssl_x509_parse($chaincert);
        $chain_public_key = openssl_get_publickey($chaincert);
        $r = openssl_x509_verify($x509, $chain_public_key);
        if ($r==1)
        {
            echo $certparsed['subject']['CN'];
            echo " was digitally signed by ";
            echo $chainparsed['subject']['CN']."\n";
        }
    }
    ?>

### See Also

- openssl_verify() - Verify signature
- openssl_get_publickey() - Alias of openssl_pkey_get_public