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.

import 'package:chilkat/chilkat.dart';

void main() {
  final mime = CkMime();
  try {
    mime.setBodyFromPlainText('This message will be signed.');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // 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 = false;

  // 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.
  final pfxPassword = 'myPfxPassword';
  final cert = CkCert();
  try {
    cert.loadPfxFile('qa_data/signer.pfx', pfxPassword);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Create the detached signature using the algorithms configured above.
  try {
    mime.addDetachedSignature(cert);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Signed with SigningAlg=${mime.signingAlg} SigningHashAlg=${mime.signingHashAlg}');
}