Add a Detached Signature (Separate Key, Header Control)

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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.

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;
  }

  // Load the certificate and its private key separately.
  final cert = CkCert();
  try {
    cert.loadFromFile('qa_data/signer.cer');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final privKey = CkPrivateKey();
  try {
    privKey.loadPemFile('qa_data/signer_privkey.pem');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // 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.
  final transferHeaderFields = true;
  try {
    mime.addDetachedSignaturePk2(cert, privKey, transferHeaderFields);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    mime.saveMime('qa_output/signed.eml');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Detached signature added (headers transferred).');
}