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

See more ECC Examples

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.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux

use chilkat();

# 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 = chilkat::CkStringBuilder->new();
$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 = chilkat::CkPrivateKey->new();
$success = $privKey->LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem");
if ($success != 1) {
    print $privKey->lastErrorText() . "\r\n";
    exit;
}

$prng = chilkat::CkPrng->new();
$ecdsa = chilkat::CkEcc->new();

# 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->put_AsnFormat(0);

$ecdsaSigBase64 = $ecdsa->signHashENC($hash,"base64",$privKey,$prng);
if ($ecdsa->get_LastMethodSuccess() != 1) {
    print $ecdsa->lastErrorText() . "\r\n";
    exit;
}

print "ECDSA signature = " . $ecdsaSigBase64 . "\r\n";

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

$pubKey = chilkat::CkPublicKey->new();
$success = $pubKey->LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem");
if ($success != 1) {
    print $pubKey->lastErrorText() . "\r\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) {
    print "Signature is valid." . "\r\n";
    exit;
}

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

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