PHP

Create ECSDA Signature using Raw r and s Format (not ASN.1)

See more ECC Examples

Demonstrates how to create an ECDSA signature using the raw r/s format.

ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:

(a) Concatenating the raw byte array of r and s
(b) Encoding both into a structured ASN.1 / DER sequence.

This example demonstrates how to create a signature that is a byte array of r and s concatenated.

Note: This example requires Chilkat v9.5.0.97 or greater.

Chilkat2 PHP

<?php

use Chilkat2\Ecc;
use Chilkat2\PrivateKey;
use Chilkat2\Prng;
use Chilkat2\PublicKey;
use Chilkat2\StringBuilder;

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

// To create an ECDSA signature, the data first needs to be hashed.  Then the hash
// is signed.

$sb = new StringBuilder();
$sb->Append('The quick brown fox jumps over the lazy dog');
$hash = $sb->GetHash('sha256', 'base64', 'utf-8');

// Load the ECDSA key to be used for signing.
$privKey = new PrivateKey();
try {
    $privKey->LoadPemFile('qa_data/ecc/secp256r1-key-pkcs8.pem');

    $prng = new Prng();
    $ecdsa = new Ecc();

    // Produce a signature that is not ASN.1, but is instead the concatenation
    // of the raw r and s signature parts.
    // This feature was added in Chilkat v9.5.0.97
    $ecdsa->AsnFormat = false;

    $ecdsaSigBase64 = $ecdsa->SignHashENC($hash, 'base64', $privKey, $prng);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo 'ECDSA signature = ', $ecdsaSigBase64, "\n";

// -----------------------------------------------------------
// Now let's verify the signature using the public key.

$pubKey = new PublicKey();
try {
    $pubKey->LoadFromFile('qa_data/ecc/secp256r1-pubkey.pem');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

// Note: When verifying, Chilkat will auto-detect the format for both kinds of ECDSA signatures (ASN.1 or binary r+s)
$result = $ecdsa->VerifyHashENC($hash, $ecdsaSigBase64, 'base64', $pubKey);
if ($result == 1) {
    echo "Signature is valid.\n";
    exit;
}

if ($result == 0) {
    echo "Signature is invalid.\n";
    exit;
}

if ($result < 0) {
    echo $ecdsa->LastErrorText, "\n";
    echo "The VerifyHashENC method call failed.\n";
    exit;
}