PHP Manual: Sign a CSR with another certificate (or itself) and generate a certificate

Description

resource openssl_csr_sign ( mixed $csr , mixed $cacert , mixed $priv_key , int $days [, array $configargs [, int $serial = 0 ]] )

openssl_csr_sign generates an x509 certificate resource from the given CSR.

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.

Parameters

csr: A CSR previously generated by openssl_csr_new. It can also be the path to a PEM encoded CSR when specified as file://path/to/csr or an exported string generated by openssl_csr_export.
cacert: The generated certificate will be signed by cacert. If cacert is NULL, the generated certificate will be a self-signed certificate.
priv_key: priv_key is the private key that corresponds to cacert.
days: days specifies the length of time for which the generated certificate will be valid, in days.
configargs: You can finetune the CSR signing by configargs. See openssl_csr_new for more information about configargs.
serial: An optional the serial number of issued certificate. If not specified it will default to 0.

Return Values

Returns an x509 certificate resource on success, FALSE on failure.

Examples

Example #1 openssl_csr_sign example - signing a CSR (how to implement your own CA)


<?php
// Let's assume that this script is set to receive a CSR that has
// been pasted into a textarea from another page
$csrdata = $_POST["CSR"];

// We will sign the request using our own "certificate authority"
// certificate.  You can use any certificate to sign another, but
// the process is worthless unless the signing certificate is trusted
// by the software/users that will deal with the newly signed certificate

// We need our CA cert and its private key
$cacert = "file://path/to/ca.crt";
$privkey = array("file://path/to/ca.key", "your_ca_key_passphrase");

$usercert = openssl_csr_sign($csrdata, $cacert, $privkey, 365);

// Now display the generated certificate so that the user can
// copy and paste it into their local configuration (such as a file
// to hold the certificate for their SSL server)
openssl_x509_export($usercert, $certout);
echo $certout;

// Show any errors that occurred here
while (($e = openssl_error_string()) !== false) {
    echo $e . "\n";
}
?>