(PHP Extension) ECDSA Sign and Verify Data using Different Hash Algorithms

Demonstrates how to create ECDSA signatures on data using different hash algorithms.

Note: This example requires Chilkat v9.5.0.85 or greater because the SignBd and VerifyBd methods were added in v9.5.0.85.

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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.

// First load an ECDSA private key to be used for signing.
$privKey = new CkPrivateKey();
$success = $privKey->LoadEncryptedPemFile('qa_data/ecc/secp256r1-key-pkcs8-secret.pem','secret');
if ($success == false) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

// Load some data to be signed.
$bd = new CkBinData();
$success = $bd->LoadFile('qa_data/hamlet.xml');
if ($success == false) {
    print 'Failed to load file to be hashed.' . "\n";
    exit;
}

$ecdsa = new CkEcc();
$prng = new CkPrng();

// Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
print 'ECDSA signing the sha256 hash of the data...' . "\n";
$sig = $ecdsa->signBd($bd,'sha256','base64',$privKey,$prng);
print 'sig = ' . $sig . "\n";

// Verify the signature against the original data.
// (We must use the same hash algorithm that was used when signing.)

// Load the public key that corresponds to the private key used for signing.
$pubKey = new CkPublicKey();
$success = $pubKey->LoadFromFile('qa_data/ecc/secp256r1-pub.pem');
if ($success == false) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

$ecc2 = new CkEcc();
$result = $ecc2->VerifyBd($bd,'sha256',$sig,'base64',$pubKey);
if ($result != 1) {
    print $ecc2->lastErrorText() . "\n";
    exit;
}

print 'Verified!' . "\n";

// ----------------------------------------------------------------------------------------
// Let's do the same thing, but with sha384 hashing...

print '--------------------------------------------' . "\n";
print 'ECDSA signing the sha384 hash of the data...' . "\n";

$sig = $ecdsa->signBd($bd,'sha384','base64',$privKey,$prng);
print 'sig = ' . $sig . "\n";

$result = $ecc2->VerifyBd($bd,'sha384',$sig,'base64',$pubKey);
if ($result != 1) {
    print $ecc2->lastErrorText() . "\n";
    exit;
}

print 'Verified!' . "\n";

?>