Dart Requires Chilkat v11.0.0+

Verify Opaque Signature and Retrieve Signing Certificates

See more Digital Signatures Examples

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example assumes the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final crypt = CkCrypt2();

  // Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
  try {
    crypt.verifyP7M('qa_data/p7m/opaqueSig.p7', 'qa_output/originalData.dat');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Alternatively, we can do it in memory...
  final binData = CkBinData();
  binData.loadFile('qa_data/p7m/opaqueSig.p7');
  // Your app should check for success, but we'll skip the check for brevity..

  // If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
  try {
    crypt.opaqueVerifyBd(binData);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // For our testing, we signed some text, so we can get it from the binData..
  print('Original Data:');
  print(binData.getString('utf-8'));

  // After any method call that verifies a signature, the crypt object will contain the certificate(s)
  // that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

  // Get each signing certificate, and build the certificate chain for each.
  final cert = CkCert();
  final certChain = CkCertChain();
  final numCerts = crypt.numSignerCerts;
  var i = 0;
  while (i < numCerts) {
    crypt.lastSignerCert(i, cert);
    print(cert.subjectDN);

    try {
      cert.buildCertChain(certChain);
    } on ChilkatException catch (e) {
      print(e.lastErrorText);
      return;
    }

    i++;
  }
}