PHP - Function openssl_pkey_get_public()

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Definition and Usage

The openssl_pkey_get_public() function will return you the public key.

Description

The function openssl_pkey_get_public() returns public key from the given certificate so that it can be used with other functions.

Syntax

openssl_pkey_get_public ( mixed $certificate ) : resource

Parameters

Return Values

PHP openssl_pkey_get_public() function returns a positive resource identifier if there is no error. It will return false if it fails.

PHP Version

This function will work from PHP Version greater than 5.0.0.

Example 1

Working of openssl_pkey_get_public() with X.509 certificate −

<?php
   $dn = array(
      "countryName" => "IN",
      "stateOrProvinceName" => "Karnataka",
      "localityName" => "test1",
      "organizationName" => "test2",
      "organizationalUnitName" => "test3",
      "commonName" => "www.test.com",
      "emailAddress" => "xyz@test.com"
   );

   // Generate a new private /public key pair
   $privkey = openssl_pkey_new();

   // Generate a certificate
   $csr = openssl_csr_new($dn, $privkey, array('digest_alg' => 'sha256'));
   $res_cert = openssl_csr_sign($csr, null, $privkey, 365);
   openssl_x509_export($res_cert, $x_509_certificate);
   echo $res_pubkey = openssl_pkey_get_public($x_509_certificate);
?>

This will produce following result −

Resource id #5

Example 2

Working of openssl_pkey_get_public() using .pem file −

<?php
   $dn = array(
      "countryName" => "IN",
      "stateOrProvinceName" => "Karnataka",
      "localityName" => "test1",
      "organizationName" => "test2",
      "organizationalUnitName" => "test3",
      "commonName" => "www.test.com",
      "emailAddress" => "xyz@test.com"
   );

   // Generate a new private /public key pair
   $privkey = openssl_pkey_new();

   // Generate a certificate
   $csr = openssl_csr_new($dn, $privkey, array('digest_alg' => 'sha256'));
   $res_cert = openssl_csr_sign($csr, null, $privkey, 365);
   openssl_x509_export_to_file($res_cert, 'C:/xampp/htdocs/modules/openssl/x_509.pem');
   echo $res_pubkey = openssl_pkey_get_public(file_get_contents('C:/xampp/htdocs/modules/openssl/x_509.pem'));
?>

This will produce following result −

Resource id #7