PHP ActiveX

ECDSA Sign and Verify

See more ECC Examples

Demonstrates how to create an ECDSA signature on the SHA256 hash of some data, and then verify. PHP ActiveX

<?php

$success = 0;

// 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 COM("Chilkat.PrivateKey");
$success = $privKey->LoadEncryptedPemFile('qa_data/ecc/secp256r1-key-pkcs8-secret.pem','secret');
if ($success == 0) {
    print $privKey->LastErrorText . "\n";
    exit;
}

// Sign the SHA256 hash of some data.
$bd = new COM("Chilkat.BinData");
$success = $bd->LoadFile('qa_data/hamlet.xml');
if ($success == 0) {
    print 'Failed to load file to be hashed.' . "\n";
    exit;
}

$crypt = new COM("Chilkat.Crypt2");
$crypt->HashAlgorithm = 'sha256';
$crypt->EncodingMode = 'base64';
$hashStr = $crypt->hashBdENC($bd);

$ecdsa = new COM("Chilkat.Ecc");
$prng = new COM("Chilkat.Prng");
// Returns ASN.1 signature as a base64 string.
$sig = $ecdsa->signHashENC($hashStr,'base64',$privKey,$prng);
print 'sig = ' . $sig . "\n";

// The signature is in ASN.1 format (which may be described as the "encoded DSS signature").
// SEQUENCE (2 elem)
//   INTEGER (255 bit) 4849395540832462044300553275435608522154141569743642905628579547100940...
//   INTEGER (255 bit) 3680701124244788134409868118208591399799457104230118295614152238560005...

// If you wish, you can get the r and s components of the signature like this:
$asn = new COM("Chilkat.Asn");
$asn->LoadEncoded($sig,'base64');
$xml = new COM("Chilkat.Xml");
$xml->LoadXml($asn->asnToXml());

print $xml->getXml() . "\n";

// We now have this:
// <?xml version="1.0" encoding="utf-8"?>
// <sequence>
//     <int>6650D422D86BA4A228B5617604E59052591B9B2C32EF324C44D09EF67E5F0060</int>
//     <int>0CFD9F6AC85042FC70F672C141BA6B2A4CAFBB906C3D907BCCC1BED62B28326F</int>
// </sequence>

// Get the "r" and "s" as hex strings
$r = $xml->getChildContentByIndex(0);
$s = $xml->getChildContentByIndex(1);

print 'r = ' . $r . "\n";
print 's = ' . $s . "\n";

// --------------------------------------------------------------------
// Now verify against the hash of the original data.

// Get the corresponding public key.
$pubKey = new COM("Chilkat.PublicKey");
$success = $pubKey->LoadFromFile('qa_data/ecc/secp256r1-pub.pem');
if ($success == 0) {
    print $pubKey->LastErrorText . "\n";
    exit;
}

// We already have the SHA256 hash of the original data (hashStr) so no need to re-do it..
$ecc2 = new COM("Chilkat.Ecc");
$result = $ecc2->VerifyHashENC($hashStr,$sig,'base64',$pubKey);
if ($result != 1) {
    print $ecc2->LastErrorText . "\n";
    exit;
}

print 'Verified!' . "\n";

// Note: If we have only r,s and wish to reconstruct the ASN.1 signature, we do it like this:
$xml2 = new COM("Chilkat.Xml");
$xml2->Tag = 'sequence';
$xml2->NewChild2('int',$r);
$xml2->NewChild2('int',$s);

$asn2 = new COM("Chilkat.Asn");
$asn2->LoadAsnXml($xml2->getXml());
$encodedSig = $asn2->getEncodedDer('base64');
print 'encoded DSS signature: ' . $encodedSig . "\n";

// You can go to https://lapo.it/asn1js/  and copy/paste the base64 encodedSig into the online tool, then press the "decode" button.
// You will see the ASN.1 such as this:

// SEQUENCE (2 elem)
//   INTEGER (255 bit) 4849395540832462044300553275435608522154141569743642905628579547100940...
//   INTEGER (255 bit) 3680701124244788134409868118208591399799457104230118295614152238560005...

?>