PHP Extension

Export a Public Key as PEM

Demonstrates the Chilkat PublicKey.GetPem method, which returns the public key in PEM format. The only argument selects the underlying DER representation: true prefers the traditional PKCS #1 form (RSA), false uses the SubjectPublicKeyInfo form.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: PEM is the most portable way to share a public key — the Base64 text block most tooling reads. The boolean picks the encoding: false produces the modern, algorithm-independent PUBLIC KEY (SubjectPublicKeyInfo), which is the usual choice; true produces the older RSA-specific RSA PUBLIC KEY for tools that require it. A public key is not sensitive, so the PEM can be distributed openly.

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<?php

include("chilkat.php");

$success = false;

//  Load a public key to export.  LoadFromFile inspects the content, so it accepts DER, PEM, XML,
//  JWK, and other supported representations.
$pubKey = new CkPublicKey();
$success = $pubKey->LoadFromFile('qa_data/public.pem');
if ($success == false) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

//  Export the public key in PEM format.  The argument selects the underlying DER representation:
//  true prefers the traditional PKCS #1 form (RSA), false uses the SubjectPublicKeyInfo form.
$preferPkcs1 = false;
$pem = $pubKey->getPem($preferPkcs1);
if ($pubKey->get_LastMethodSuccess() == false) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

print $pem . "\n";

?>