Create an Opaque Signature with a Separate Private Key

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Demonstrates the Chilkat Mime.ConvertToSignedPk method, which creates an opaque signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

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 an opaque signature when the certificate and private key are supplied separately.  The
  // 1st argument is the signer certificate and the 2nd is its private key.
  try {
    mime.convertToSignedPk(cert, privKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

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

  print('Message converted to an opaque signed message.');
}