(Perl) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

Note: This example requires Chilkat v11.0.0 or greater.

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

use chilkat();

$success = 0;

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

$privKey = chilkat::CkPrivateKey->new();

# Load the private key from an RSA PEM file:
$success = $privKey->LoadAnyFormatFile("raul_privateKey.key","a0123456789");
if ($success == 0) {
    print $privKey->lastErrorText() . "\r\n";
    exit;
}

$rsa = chilkat::CkRsa->new();

# Import the private key into the RSA component:
$success = $rsa->UsePrivateKey($privKey);
if ($success == 0) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

# This example will sign a string, and receive the signature
# in a hex-encoded string.  Therefore, set the encoding mode
# to "hex":
$rsa->put_EncodingMode("hex");

$strData = "This is the string to be signed.";

# Sign the string using the sha256 hash algorithm.
# Other valid choices are sha1, sha384, sha512 and others.
$hexSig = $rsa->signStringENC($strData,"sha256");
if ($rsa->get_LastMethodSuccess() == 0) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

print $hexSig . "\r\n";

# Now verify with the public key.
# This example shows how to use the public key from 
# a digital certificate (.cer file)
$cert = chilkat::CkCert->new();
$success = $cert->LoadFromFile("raul_publicKey.cer");
if ($success == 0) {
    print $cert->lastErrorText() . "\r\n";
    exit;
}

$pubKey = chilkat::CkPublicKey->new();
$cert->GetPublicKey($pubKey);

$rsa2 = chilkat::CkRsa->new();
$success = $rsa2->UsePublicKey($pubKey);
if ($success == 0) {
    print $rsa2->lastErrorText() . "\r\n";
    exit;
}

# Verify the signature against the original data:
$rsa2->put_EncodingMode("hex");
$success = $rsa2->VerifyStringENC($strData,"sha256",$hexSig);
if ($success == 0) {
    print $rsa2->lastErrorText() . "\r\n";
    exit;
}

print "Signature verified!" . "\r\n";

# Verify with incorrect data:
$success = $rsa2->VerifyStringENC("something else","sha256",$hexSig);
if ($success != 1) {
    print "Signature not verified! (which was expected in this case)" . "\r\n";
}
else {
    print "Hmmm... that's not right..." . "\r\n";
}