MIME S/MIME Signing Algorithm Properties

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Demonstrates the properties that control S/MIME signing: SigningAlg (the RSA signature scheme, PKCS1-V1_5 or RSASSA-PSS), SigningHashAlg (the message-digest algorithm), Micalg and Protocol (the micalg and protocol parameters of a multipart/signed Content-Type), and UseXPkcs7 (whether historical x-pkcs7 media-type names are used). The properties are configured before creating a detached signature.

<?php

$success = 0;

$mime = new COM("Chilkat.Mime");
$success = $mime->SetBodyFromPlainText('This message will be signed.');
if ($success == 0) {
    print $mime->LastErrorText . "\n";
    exit;
}

//  SigningAlg is the RSA signature scheme.  The default is PKCS1-V1_5; set RSASSA-PSS (or pss) for
//  RSASSA-PSS.
$mime->SigningAlg = 'PKCS1-V1_5';

//  SigningHashAlg is the message-digest algorithm.  The default is sha256.
$mime->SigningHashAlg = 'sha256';

//  Micalg and Protocol are the micalg and protocol parameters written into a multipart/signed
//  Content-Type header field.  They are normally set automatically, but can be controlled here.
$mime->Micalg = 'sha-256';
$mime->Protocol = 'application/pkcs7-signature';

//  UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
$mime->UseXPkcs7 = 0;

//  Load a signing certificate (with private key access) from a PFX.  The PFX password should come
//  from a secure source rather than being hard-coded.
$pfxPassword = 'myPfxPassword';
$cert = new COM("Chilkat.Cert");
$success = $cert->LoadPfxFile('qa_data/signer.pfx',$pfxPassword);
if ($success == 0) {
    print $cert->LastErrorText . "\n";
    exit;
}

//  Create the detached signature using the algorithms configured above.
$success = $mime->AddDetachedSignature($cert);
if ($success == 0) {
    print $mime->LastErrorText . "\n";
    exit;
}

print 'Signed with SigningAlg=' . $mime->SigningAlg . ' SigningHashAlg=' . $mime->SigningHashAlg . "\n";

?>