Perl Requires Chilkat v9.5.0.97+

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.

Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# 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.

my $sb = Chilkat2::StringBuilder->new;
$sb->Append('The quick brown fox jumps over the lazy dog');
my $hash = $sb->GetHash('sha256', 'base64', 'utf-8');

# Load the ECDSA key to be used for signing.
my $privKey = Chilkat2::PrivateKey->new;
my $success = $privKey->LoadPemFile('qa_data/ecc/secp256r1-key-pkcs8.pem');
if (!$success) {
    print $privKey->LastErrorText, "\n";
    exit;
}

my $prng = Chilkat2::Prng->new;
my $ecdsa = Chilkat2::Ecc->new;

# Produce a signature that is not ASN.1, but is instead the concatenation
# of the raw r and s signature parts.
$ecdsa->AsnFormat(0);

my $ecdsaSigBase64 = $ecdsa->SignHashENC($hash, 'base64', $privKey, $prng);
if (!$ecdsa->LastMethodSuccess) {
    print $ecdsa->LastErrorText, "\n";
    exit;
}

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

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

my $pubKey = Chilkat2::PublicKey->new;
$success = $pubKey->LoadFromFile('qa_data/ecc/secp256r1-pubkey.pem');
if (!$success) {
    print $pubKey->LastErrorText, "\n";
    exit;
}

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

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

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