Perl

Add a Detached Signature (Header Placement Control)

Demonstrates the Chilkat Mime.AddDetachedSignature2 method, which creates the same multipart/signed structure as AddDetachedSignature, with a second argument controlling whether the existing message header fields are transferred 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: Signing wraps the content in a new outer multipart/signed, which raises the question of where the message-level headers (Subject, From, To) should live. This variant lets you choose: transfer them up to the outer entity so the signed message looks like a normal email, or leave them on the inner part. Transferring is typical for email; the finer control matters when the signed entity is embedded in a larger structure.

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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 signing certificate (which must have access to its private key) from a PFX file.
# The PFX password should come from a secure source rather than being hard-coded.
my $pfxPassword = 'myPfxPassword';
my $cert = Chilkat2::Cert->new;
$success = $cert->LoadPfxFile('qa_data/signer.pfx', $pfxPassword);
if (!$success) {
    print $cert->LastErrorText, "\n";
    exit;
}

# AddDetachedSignature2 is the same as AddDetachedSignature, but the 2nd argument controls whether
# the existing message header fields are transferred to the new outer multipart/signed entity.
my $transferHeaderFields = 1;
$success = $mime->AddDetachedSignature2($cert, $transferHeaderFields);
if (!$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";