Dart Requires Chilkat v11.0.0+

Validate a .pkpass Archive

See more Digital Signatures Examples

Opens a .pkpass archive (which is just a .zip renamed to .pkpass) and validates the contents. The hashes in the manifest are compared with the computed hash values for each individual file. If all computed hash values match, then the signature is verified. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  var success = false;

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

  final crypt = CkCrypt2();
  final zip = CkZip();

  success = true;
  try {
    zip.openZip('qa_data/pkpass/invalid.pkpass');
  } on ChilkatException {
    success = false;
  }
  if (!success) {
    print(zip.lastErrorText);
    return;
  }

  // Get the contents of the manifest.json file, which contains something like this:

  // {
  //   "icon.png" : "0296b01347b3173e98438a003b0e88986340b2d8",
  //   "logo.png" : "25de09e2d3b01ce1fe00c2ca9a90a2be1aaa05cf",
  //   "icon@2x.png" : "5afd9585b08c65fdf105a90c8bd643407cba2787",
  //   "pass.json" : "145ea5a5db784fff485126c77ecf7a1fc2a88ee7",
  //   "strip@2x.png" : "468fa7bc93e6b55342b56fda09bdce7c829d7d46",
  //   "strip.png" : "736d01f84cb73d06e8a9932e43076d68f19461ff"
  // }

  final ent = CkZipEntry();
  success = zip.entryOf('manifest.json', ent);
  if (!success) {
    print(zip.lastErrorText);
    return;
  }

  // Get the exact content of the manifest.json for later signature verification.
  final bdManifest = CkBinData();
  success = true;
  try {
    ent.unzipToBd(bdManifest);
  } on ChilkatException {
    success = false;
  }

  final json = CkJsonObject();
  json.emitCompact = false;
  json.load(ent.unzipToString(0, 'utf-8'));
  print(json.emit());

  // For each file in the JSON, get the filename and hex hash value.
  crypt.encodingMode = 'hexlower';
  crypt.hashAlgorithm = 'sha1';

  var someHashesFailed = false;
  var filename = '';
  final sbHashHex = CkStringBuilder();
  final bdFileData = CkBinData();
  final numMembers = json.size;
  var i = 0;
  while (i < numMembers) {
    filename = json.nameAt(i);
    sbHashHex.clear();
    sbHashHex.append(json.stringAt(i));

    success = zip.entryOf(filename, ent);
    if (!success) {
      print(zip.lastErrorText);
      return;
    }

    // Get the data for this file.
    bdFileData.clear();
    success = true;
    try {
      ent.unzipToBd(bdFileData);
    } on ChilkatException {
      success = false;
    }

    final computedHashHex = crypt.hashBdENC(bdFileData);
    if (!sbHashHex.contentsEqual(computedHashHex, false)) {
      print('Computed hash does not match stored hash for $filename');
      print('  computed: $computedHashHex');
      print('  stored:   ${sbHashHex.getAsString()}');
      someHashesFailed = true;
    } else {
      print('hash verified for $filename($computedHashHex)');
    }

    i++;
  }

  if (someHashesFailed) {
    print('Some hashes failed.');
    return;
  }

  // Let's verify the signature..
  // First get the signature.
  success = zip.entryOf('signature', ent);
  if (!success) {
    print(zip.lastErrorText);
    return;
  }

  final bdSignature = CkBinData();
  success = true;
  try {
    ent.unzipToBd(bdSignature);
  } on ChilkatException {
    success = false;
  }

  // Show the contents of the signature in base64 encoding.
  print('Signature:');
  print(bdSignature.getEncoded('base64_mime'));
  print('----');

  // Verify the signature against the manifest.json
  crypt.encodingMode = 'base64';
  var verified = true;
  try {
    crypt.verifyBdENC(bdManifest, bdSignature.getEncoded('base64'));
  } on ChilkatException {
    verified = false;
  }
  if (!verified) {
    print(crypt.lastErrorText);
  }

  print('signature verified = $verified');
}