(PHP Extension) Ed25519 Key Exchange (Shared Secret)

Demonstrates how to create an Ed25519 shared secret for use in key exchange.

Note: This example requires Chilkat v9.5.0.83 or greater.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// Alice's private key, a:
//     77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a
// Alice's public key, X25519(a, 9):
//     8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a
// Bob's private key, b:
//     5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb
// Bob's public key, X25519(b, 9):
//     de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f
// Their shared secret, K:
//     4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742

$alicePrivKey = '77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a';
$bobPubKey = 'de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f';

$privKey = new CkPrivateKey();
// This example shows only one way of loading an Ed25519 private key.
// Chilkat can load other formats (JWK, PEM, ASN.1 DER, etc.)  
// You may do so by calling LoadAnyFormat or LoadAnyFormatFile.
$success = $privKey->LoadEd25519($alicePrivKey,'');
if ($success == false) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

$pubKey = new CkPublicKey();
$success = $pubKey->LoadEd25519($bobPubKey);
if ($success == false) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

// Create the shared secret:
$eddsa = new CkEdDSA();
$sharedSecret = $eddsa->sharedSecretENC($privKey,$pubKey,'hexlower');
if ($eddsa->get_LastMethodSuccess() == false) {
    print $eddsa->lastErrorText() . "\n";
    exit;
}

print 'Computed: ' . $sharedSecret . "\n";
print 'Expected: 4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742' . "\n";

?>