PHP | openssl_pkey_get_public() Function

Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP openssl_pkey_get_public() Function.

The openssl_pkey_get_public() function returns the public key.

This built-in function returns the public key from the given certificate so that it can be used with other functions.

syntax

Following below is the syntax to use this function -

openssl_pkey_get_public ( mixed $certificate ) : resource

READ: PHP | openssl_pkey_get_private Function

Parameter Details

Sr.No	Parameter	Description
1	certificate	You can make use of following certificates : 1. An X.509 certificate resource 2. Public key from the file in the format file://path/to/file.pem. 3. A PEM formatted public key.

Return Value

This built-in PHP function returns a positive resource identifier if there is no error, else it returns false if it fails.

PHP Version

This PHP function works from PHP version greater than 5.0.0.

Example1

The following example illustrates the usage of PHP openssl_pkey_get_public() function with X.509 certificate -

<?php
   $dn = array(
      "countryName" => "NRA",
      "stateOrProvinceName" => "Rivers",
      "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);
?>

Output

When the above code is executed, it will produce the following result -

Resource id #5

Example2

The following example illustrates the usage of PHP openssl_pkey_get_public() function using .pem file -

<?php
   $dn = array(
      "countryName" => "NRA",
      "stateOrProvinceName" => "Rivers",
      "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'));
?>

Output

When the above code is executed, it will produce the following result -

Resource id #7

READ: PHP | openssl_pkey_new() Function

Alright guys! This is where we are going to be rounding up for this tutorial post. In our next tutorial, we will be studying about the openssl_pkey_export_to_file() Function.

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