Perl Requires Chilkat v11.0.0+

RSASSA-PSS Sign String to Create Base64 PCKS7 Signature

See more Digital Signatures Examples

Signs a string to create a PKCS7 signature in the base64 encoding. The signature algorithm is RSASSA-PSS with SHA256. 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.

my $crypt = Chilkat2::Crypt2->new;

# Get a digital certificate with private key from a .pfx
# (Chilkat has many different ways to provide a cert + private key for siging.
# Using a PFX is just one possible option.)
my $pfx = Chilkat2::Pfx->new;
my $success = $pfx->LoadPfxFile('qa_data/rsassa-pss/privatekey.pfx', 'PFX_PASSWORD');
if (!$success) {
    print $pfx->LastErrorText, "\n";
    exit;
}

# Get the certificate to be used for signing.
# (The typical case for a PFX is that it contains a cert with an associated private key,
# as well as other certificates in the chain of authentication.  The cert with the private
# key should be in the first position at index 0.)

my $cert = Chilkat2::Cert->new;
$success = $pfx->CertAt(0, $cert);
if (!$success) {
    print $pfx->LastErrorText, "\n";
    exit;
}

$crypt->SetSigningCert($cert);

# Indicate that RSASSA-PSS with SHA256 should be used.
$crypt->SigningAlg('pss');
$crypt->HashAlgorithm('sha256');

$crypt->EncodingMode('base64');

# Sign a string and return the base64 PKCS7 detached signature
my $originalText = 'This is a test';
my $pkcs7sig = $crypt->SignStringENC($originalText);
print "Detached Signature:\n";
print $pkcs7sig, "\n";

# This signature looks like this:
# MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBgl .. YToLqEwTdU87ox5g7rvw==

# The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
# then copy-and-paste the Base64 signature into the form and decode..

# The signature can be verified against the original data like this:
$success = $crypt->VerifyStringENC($originalText, $pkcs7sig);
print 'Signature verified: ', ($success ? 1 : 0), "\n";
$success = $crypt->VerifyStringENC('Not the original text', $pkcs7sig);
print 'Signature verified: ', ($success ? 1 : 0), "\n";

# Now we'll create an opaque signature (the opposite of a detached signature).
# An opaque signature is a PKCS7 message that contains both the original data and
# the signature.  The verification process extracts the original data.
my $opaqueSig = $crypt->OpaqueSignStringENC($originalText);
print "Opaque Signature:\n";
print $opaqueSig, "\n";

# The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
# then copy-and-paste the Base64 signature into the form and decode..

# We can verify and extract the original data:
my $origTxt = $crypt->OpaqueVerifyStringENC($opaqueSig);
if (!$crypt->LastMethodSuccess) {
    print "Signature verification failed.\n";
    print $crypt->LastErrorText, "\n";
    exit;
}

print "Signature verified.\n";
print 'Extracted text:', $origTxt, "\n";