PHP - Function openssl_pkey_new()

Quiz

Definition and Usage

The openssl_pkey_new() function will return resource identifier that has new private and public key pair.

Description

The function openssl_pkey_new() returns a resource identifier. You can make use of openssl_pkey_get_details() function to get all the details of the key generated. The key (public/private pair) is used later with other openssl function like openssl_sign(), openssl_csr_new() - to get CSR certificate, that helps to create cryptographic digital signature.

Syntax

openssl_pkey_new ([ array $configargs ] ) : resource

Parameters

Sr.No	Parameter	Description
1	configargs	The parameter configargs is the configuration details that need to be given to the function to generate the private/public key pair. The details are described below.

configargs

By default openssl_pkey_new() makes use of configuration details present in openssl.cnf. But using configargs you can overwrite them.The config details are as follows:

key in configargs	type	key used in openssl.conf	description
digest_alg	string	default_md	Digest methods that you get from openssl_get_md_methods().
x509_extensions	string	x509_extensions	Extensions used when creating an x509 certificate.
req_extensions	string	req_extensions	Extensions used when creating a CSR.
private_key_bits	integer	default_bits	Specifies how many bits to be used while generating a private key.
private_key_type	integer	none	The type of private key to create. It can be one of OPENSSL_KEYTYPE_DSA, OPENSSL_KEYTYPE_DH, OPENSSL_KEYTYPE_RSA or OPENSSL_KEYTYPE_EC. The default value is OPENSSL_KEYTYPE_RSA.
encrypt_key	boolean	encrypt_key	Whether the exported key be encrypted?
encrypt_key_cipher	integer	none	Cipher constants like OPENSSL_CIPHER_RC2_40 (integer),OPENSSL_CIPHER_RC2_128 (integer),OPENSSL_CIPHER_RC2_64 (integer),OPENSSL_CIPHER_DES (integer), OPENSSL_CIPHER_3DES (integer) etc.
curve_name	string	none	One of the curve name returned by this function openssl_get_curve_names().
config	string	N/A	You can change the configuration in openssl.conf as per your requirement and give the path of it here.

Return Values

PHP openssl_pkey_new() function returns a resource identifier if there is no error. It will return false if the key generation fails.

PHP Version

This function will work from PHP Version greater than 5.0.0.

Example 1

Working of openssl_pkey_new():

<?php
   // Generate a new private (and public) key pair
   $privkey = openssl_pkey_new(array(
      "digest_alg"=>'md5',
      "private_key_bits" => 2048,
      "private_key_type" => OPENSSL_KEYTYPE_RSA,
   ));
   var_dump($privkey);
?>

This will produce the following result:

resource(2) of type (OpenSSL key)

Example 2

Working of openssl_pkey_new() and openssl_pkey_get_details:

<?php
   // Generate a new private (and public) key pair
   $privkey = openssl_pkey_new(array(
      "digest_alg"=>'md5',
      "private_key_bits" => 2048,
      "private_key_type" => OPENSSL_KEYTYPE_RSA,
   ));
   $key_details = openssl_pkey_get_details($privkey);
   print_r($key_details);
?>

This will produce the following result:

Array (
   [bits] => 2048
   [key] => -----BEGIN PUBLIC KEY-----
   MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA1IGWxnWzICSkjrOVrYkw
   9EKpIhcAYbhaymiwQY/ii9d7hnuGhpjjitDxzFftGafL6XOFKOhgbO2yrcpFxRKu
   AY3t5wyUcqUJV6CNwV2Hipk90psUcTmK3+pcCzcqCKr7sLWlHI48lse92xane8Sf
   CATNNbr9vmqUaTZ9FQqWihm3o/rNGuZTwMSKvcKsVguFpwrEDJaSLP1nt7RSHGc+
   PixQSXp3PtQCH+S0CM9jt1jD9NkYXuuAlNbrsPm1fl2zAGR5Vh15evz5765lZ2mH
   LIZScfsO/qgai3R6foaBlJM5tiSeiVZgnnQDKFBi5XK2GhzDnKggJe4tdY7awTFm
   CQIDAQAB
   -----END PUBLIC KEY-----

   [rsa] => Array (
      [n] => u $0B"aZhA{{Ws(`lEr	W]=q9\7*>,PIzw>cX^~]dyVyzegi,Rqtz~9$V`t(Pbr %-u1f	
         [e] => 
         [d] => F"34!KyFRlY9]A@f~ >u)1bKrpHEkLBEy'3-/PdjeFV1?.O:bl2zU{{*A z\96=V]"k2w>r6/-Z_8!YIL_3Ym.p^>I:oZ"=81:
         [dmp1] => z"TW*m$HQ$0saj #
         P*PQG\42a26(5K7zjxj7@e$.6bDq]]I}Lmd54)@:#
         [dmq1] => +4}\dcRKBw\E6%_m$39FhDuz$8HPK^Kk]eg>X" !=z=7V6q~3VtP$Okgv3=W\m	J5^Kat~U.!lv#z*	r
      )
      [type] => 0
   )

Example 3

To read public key from openssl_pkey_new():

<?php
   echo "The hash of Welcome to Tutorialspoint is - ". hash('crc32b', 'Welcome to Tutorialspoint');
?>

This will produce following result:

Example 4

To store public key from openssl_pkey_new() in a file:

<?php
   // Generate a new private (and public) key pair

   $privkey = openssl_pkey_new(array(
      "digest_alg"=>'md5',
      "private_key_bits" => 2048,
      "private_key_type" => OPENSSL_KEYTYPE_RSA,
   ));
   $keydetails = openssl_pkey_get_details($privkey);

   // To save the public key to a file 
   file_put_contents('mypublic.key', $keydetails['key']);
?>

The contents of file mypublic.key is:

php_function_reference.htm

Print Page