Delphi DLL

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. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Zip, JsonObject, StringBuilder, BinData, ZipEntry, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
crypt: HCkCrypt2;
zip: HCkZip;
ent: HCkZipEntry;
bdManifest: HCkBinData;
json: HCkJsonObject;
someHashesFailed: Boolean;
filename: PWideChar;
sbHashHex: HCkStringBuilder;
bdFileData: HCkBinData;
numMembers: Integer;
i: Integer;
computedHashHex: PWideChar;
bdSignature: HCkBinData;
verified: Boolean;

begin
success := False;

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

crypt := CkCrypt2_Create();
zip := CkZip_Create();

success := CkZip_OpenZip(zip,'qa_data/pkpass/invalid.pkpass');
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    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 := CkZipEntry_Create();
success := CkZip_EntryOf(zip,'manifest.json',ent);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

// Get the exact content of the manifest.json for later signature verification.
bdManifest := CkBinData_Create();
success := CkZipEntry_UnzipToBd(ent,bdManifest);

json := CkJsonObject_Create();
CkJsonObject_putEmitCompact(json,False);
CkJsonObject_Load(json,CkZipEntry__unzipToString(ent,0,'utf-8'));
Memo1.Lines.Add(CkJsonObject__emit(json));

// For each file in the JSON, get the filename and hex hash value.
CkCrypt2_putEncodingMode(crypt,'hexlower');
CkCrypt2_putHashAlgorithm(crypt,'sha1');

someHashesFailed := False;

sbHashHex := CkStringBuilder_Create();
bdFileData := CkBinData_Create();
numMembers := CkJsonObject_getSize(json);
i := 0;
while i < numMembers do
  begin
    filename := CkJsonObject__nameAt(json,i);
    CkStringBuilder_Clear(sbHashHex);
    CkStringBuilder_Append(sbHashHex,CkJsonObject__stringAt(json,i));

    success := CkZip_EntryOf(zip,filename,ent);
    if (success = False) then
      begin
        Memo1.Lines.Add(CkZip__lastErrorText(zip));
        Exit;
      end;

    // Get the data for this file.
    CkBinData_Clear(bdFileData);
    success := CkZipEntry_UnzipToBd(ent,bdFileData);

    computedHashHex := CkCrypt2__hashBdENC(crypt,bdFileData);
    if (CkStringBuilder_ContentsEqual(sbHashHex,computedHashHex,False) = False) then
      begin
        Memo1.Lines.Add('Computed hash does not match stored hash for ' + filename);
        Memo1.Lines.Add('  computed: ' + computedHashHex);
        Memo1.Lines.Add('  stored:   ' + CkStringBuilder__getAsString(sbHashHex));
        someHashesFailed := True;
      end
    else
      begin
        Memo1.Lines.Add('hash verified for ' + filename + '(' + computedHashHex + ')');
      end;

    i := i + 1;
  end;

if (someHashesFailed = True) then
  begin
    Memo1.Lines.Add('Some hashes failed.');
    Exit;
  end;

// Let's verify the signature..
// First get the signature.
success := CkZip_EntryOf(zip,'signature',ent);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

bdSignature := CkBinData_Create();
success := CkZipEntry_UnzipToBd(ent,bdSignature);

// Show the contents of the signature in base64 encoding.
Memo1.Lines.Add('Signature:');
Memo1.Lines.Add(CkBinData__getEncoded(bdSignature,'base64_mime'));
Memo1.Lines.Add('----');

// Verify the signature against the manifest.json
CkCrypt2_putEncodingMode(crypt,'base64');
verified := CkCrypt2_VerifyBdENC(crypt,bdManifest,CkBinData__getEncoded(bdSignature,'base64'));
if (verified = False) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
  end;
Memo1.Lines.Add('signature verified = ' + IntToStr(Ord(verified)));

CkCrypt2_Dispose(crypt);
CkZip_Dispose(zip);
CkZipEntry_Dispose(ent);
CkBinData_Dispose(bdManifest);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbHashHex);
CkBinData_Dispose(bdFileData);
CkBinData_Dispose(bdSignature);

end;