Perl

Add a Detached Signature (Separate Key, Header Control)

Demonstrates the Chilkat Mime.AddDetachedSignaturePk2 method, which creates a detached signature with a separately supplied certificate and private key, and a third argument controlling transfer of the existing message header fields to the new outer entity.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: This combines the two variations — certificate and key supplied separately, plus explicit header placement — for the case that needs both. It is the most flexible of the detached-signature methods; choose it when your key material is separate and you also care about where the message headers end up on the signed result.

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use strict;
use warnings;
use Chilkat2;

my $mime = Chilkat2::Mime->new;
my $success = $mime->SetBodyFromPlainText('This message will be signed.');
if (!$success) {
    print $mime->LastErrorText, "\n";
    exit;
}

# Load the certificate and its private key separately.
my $cert = Chilkat2::Cert->new;
$success = $cert->LoadFromFile('qa_data/signer.cer');
if (!$success) {
    print $cert->LastErrorText, "\n";
    exit;
}

my $privKey = Chilkat2::PrivateKey->new;
$success = $privKey->LoadPemFile('qa_data/signer_privkey.pem');
if (!$success) {
    print $privKey->LastErrorText, "\n";
    exit;
}

# Create a detached signature with separately supplied cert and private key, where the 3rd
# argument controls whether the existing message header fields are transferred to the new outer
# multipart/signed entity.
my $transferHeaderFields = 1;
$success = $mime->AddDetachedSignaturePk2($cert, $privKey, $transferHeaderFields);
if (!$success) {
    print $mime->LastErrorText, "\n";
    exit;
}

$success = $mime->SaveMime('qa_output/signed.eml');
if (!$success) {
    print $mime->LastErrorText, "\n";
    exit;
}

print "Detached signature added (headers transferred).\n";