Pascal (Lazarus/Delphi)

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. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Zip,
  Chilkat.JsonObject,
  Chilkat.StringBuilder,
  Chilkat.BinData,
  Chilkat.ZipEntry,
  Chilkat.Crypt2;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  crypt: TCrypt2;
  zip: TZip;
  ent: TZipEntry;
  bdManifest: TBinData;
  json: TJsonObject;
  someHashesFailed: Boolean;
  filename: string;
  sbHashHex: TStringBuilder;
  bdFileData: TBinData;
  numMembers: Integer;
  i: Integer;
  computedHashHex: string;
  bdSignature: TBinData;
  verified: Boolean;

begin
  success := False;

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

  crypt := TCrypt2.Create;
  zip := TZip.Create;

  success := zip.OpenZip('qa_data/pkpass/invalid.pkpass');
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  //  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"
  //  }

  ent := TZipEntry.Create;
  success := zip.EntryOf('manifest.json',ent);
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  //  Get the exact content of the manifest.json for later signature verification.
  bdManifest := TBinData.Create;
  success := ent.UnzipToBd(bdManifest);

  json := TJsonObject.Create;
  json.EmitCompact := False;
  json.Load(ent.UnzipToString(0,'utf-8'));
  WriteLn(json.Emit());

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

  someHashesFailed := False;

  sbHashHex := TStringBuilder.Create;
  bdFileData := TBinData.Create;
  numMembers := json.Size;
  i := 0;
  while i < numMembers do
    begin
      filename := json.NameAt(i);
      sbHashHex.Clear();
      sbHashHex.Append(json.StringAt(i));

      success := zip.EntryOf(filename,ent);
      if (success = False) then
        begin
          WriteLn(zip.LastErrorText);
          Exit;
        end;

      //  Get the data for this file.
      bdFileData.Clear();
      success := ent.UnzipToBd(bdFileData);

      computedHashHex := crypt.HashBdENC(bdFileData);
      if (sbHashHex.ContentsEqual(computedHashHex,False) = False) then
        begin
          WriteLn('Computed hash does not match stored hash for ' + filename);
          WriteLn('  computed: ' + computedHashHex);
          WriteLn('  stored:   ' + sbHashHex.GetAsString());
          someHashesFailed := True;
        end
      else
        begin
          WriteLn('hash verified for ' + filename + '(' + computedHashHex + ')');
        end;

      i := i + 1;
    end;

  if (someHashesFailed = True) then
    begin
      WriteLn('Some hashes failed.');
      Exit;
    end;

  //  Let's verify the signature..
  //  First get the signature.
  success := zip.EntryOf('signature',ent);
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  bdSignature := TBinData.Create;
  success := ent.UnzipToBd(bdSignature);

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

  //  Verify the signature against the manifest.json
  crypt.EncodingMode := 'base64';
  verified := crypt.VerifyBdENC(bdManifest,bdSignature.GetEncoded('base64'));
  if (verified = False) then
    begin
      WriteLn(crypt.LastErrorText);
    end;
  WriteLn('signature verified = ' + verified);


  crypt.Free;
  zip.Free;
  ent.Free;
  bdManifest.Free;
  json.Free;
  sbHashHex.Free;
  bdFileData.Free;
  bdSignature.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.