(PHP 4 >= 4.2.0, PHP 5, PHP 7)
openssl_csr_new — Generates a CSR
$dn
   , resource &$privkey
   [, array $configargs
   [, array $extraattribs
  ]] ) : mixed
   openssl_csr_new() generates a new CSR (Certificate Signing Request)
   based on the information provided by dn.
  
Note: You need to have a valid openssl.cnf installed for this function to operate correctly. See the notes under the installation section for more information.
dnThe Distinguished Name or subject fields to be used in the certificate.
privkey
       privkey should be set to a private key that was
       previously generated by openssl_pkey_new() (or
       otherwise obtained from the other openssl_pkey family of functions).
       The corresponding public portion of the key will be used to sign the
       CSR.
      
configargs
       By default, the information in your system openssl.conf
       is used to initialize the request; you can specify a configuration file
       section by setting the config_section_section key of
       configargs.  You can also specify an alternative
       openssl configuration file by setting the value of the
       config key to the path of the file you want to use.
       The following keys, if present in configargs
       behave as their equivalents in the openssl.conf, as
       listed in the table below.
       
| configargskey | type | openssl.confequivalent | description | 
|---|---|---|---|
| digest_alg | string | default_md | Digest method or signature hash, usually one of openssl_get_md_methods() | 
| x509_extensions | string | x509_extensions | Selects which extensions should be used when creating an x509 certificate | 
| req_extensions | string | req_extensions | Selects which extensions should be used when creating a CSR | 
| private_key_bits | integer | default_bits | Specifies how many bits should be used to generate a private key | 
| private_key_type | integer | none | Specifies the type of private key to create.  This can be one
            of OPENSSL_KEYTYPE_DSA,OPENSSL_KEYTYPE_DH,OPENSSL_KEYTYPE_RSAorOPENSSL_KEYTYPE_EC.
            The default value isOPENSSL_KEYTYPE_RSA. | 
| encrypt_key | boolean | encrypt_key | Should an exported key (with passphrase) be encrypted? | 
| encrypt_key_cipher | integer | none | One of cipher constants. | 
| curve_name | string | none | One of openssl_get_curve_names(). | 
| config | string | N/A | Path to your own alternative openssl.conf file. | 
extraattribs
       extraattribs is used to specify additional
       configuration options for the CSR.  Both dn and
       extraattribs are associative arrays whose keys are
       converted to OIDs and applied to the relevant part of the request.
      
   Returns the CSR or FALSE on failure.
  
| Version | Description | 
|---|---|
| 7.1.0 | configargsnow also supportscurve_name. | 
Example #1 Creating a self-signed certificate
<?php
// for SSL server certificates the commonName is the domain name to be secured
// for S/MIME email certificates the commonName is the owner of the email address
// location and identification fields refer to the owner of domain or email subject to be secured
$dn = array(
    "countryName" => "GB",
    "stateOrProvinceName" => "Somerset",
    "localityName" => "Glastonbury",
    "organizationName" => "The Brain Room Limited",
    "organizationalUnitName" => "PHP Documentation Team",
    "commonName" => "Wez Furlong",
    "emailAddress" => "wez@example.com"
);
// Generate a new private (and public) key pair
$privkey = openssl_pkey_new(array(
    "private_key_bits" => 2048,
    "private_key_type" => OPENSSL_KEYTYPE_RSA,
));
// Generate a certificate signing request
$csr = openssl_csr_new($dn, $privkey, array('digest_alg' => 'sha256'));
// Generate a self-signed cert, valid for 365 days
$x509 = openssl_csr_sign($csr, null, $privkey, $days=365, array('digest_alg' => 'sha256'));
// Save your private key, CSR and self-signed cert for later use
openssl_csr_export($csr, $csrout) and var_dump($csrout);
openssl_x509_export($x509, $certout) and var_dump($certout);
openssl_pkey_export($privkey, $pkeyout, "mypassword") and var_dump($pkeyout);
// Show any errors that occurred here
while (($e = openssl_error_string()) !== false) {
    echo $e . "\n";
}
?>
Example #2 Creating a self-signed ECC certificate (as of PHP 7.1.0)
<?php
$subject = array(
    "commonName" => "docs.php.net",
);
// Generate a new private (and public) key pair
$private_key = openssl_pkey_new(array(
    "private_key_type" => OPENSSL_KEYTYPE_EC,
    "curve_name" => 'prime256v1',
));
// Generate a certificate signing request
$csr = openssl_csr_new($subject, $private_key, array('digest_alg' => 'sha384'));
// Generate self-signed EC cert
$x509 = openssl_csr_sign($csr, null, $private_key, $days=365, array('digest_alg' => 'sha384'));
openssl_x509_export_to_file($x509, 'ecc-cert.pem');
openssl_pkey_export_to_file($private_key, 'ecc-private.key');
?>