(C# UWP/WinRT) Validate a .pkpass Archive

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.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

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

Chilkat.Crypt2 crypt = new Chilkat.Crypt2();
Chilkat.Zip zip = new Chilkat.Zip();

bool success = await zip.OpenZipAsync("qa_data/pkpass/invalid.pkpass");
if (success == false) {
    Debug.WriteLine(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"
// }

Chilkat.ZipEntry ent = zip.GetEntryByName("manifest.json");
if (zip.LastMethodSuccess == false) {
    Debug.WriteLine("manifest.json entry not found.");
    return;
}

// Get the exact content of the manifest.json for later signature verification.
Chilkat.BinData bdManifest = new Chilkat.BinData();
success = await ent.UnzipToBdAsync(bdManifest);

Chilkat.JsonObject json = new Chilkat.JsonObject();
json.EmitCompact = false;
json.Load(await ent.UnzipToStringAsync(0,"utf-8"));
Debug.WriteLine(json.Emit());

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

bool someHashesFailed = false;
string filename;
Chilkat.StringBuilder sbHashHex = new Chilkat.StringBuilder();
Chilkat.BinData bdFileData = new Chilkat.BinData();
int numMembers = json.Size;
int i = 0;
while (i < numMembers) {
    filename = json.NameAt(i);
    sbHashHex.Clear();
    sbHashHex.Append(json.StringAt(i));

    ent = zip.GetEntryByName(filename);
    if (zip.LastMethodSuccess == false) {
        Debug.WriteLine(filename + " not found in the pkpass file.");
        return;
    }

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

    string computedHashHex = crypt.HashBdENC(bdFileData);
    if (sbHashHex.ContentsEqual(computedHashHex,false) == false) {
        Debug.WriteLine("Computed hash does not match stored hash for " + filename);
        Debug.WriteLine("  computed: " + computedHashHex);
        Debug.WriteLine("  stored:   " + sbHashHex.GetAsString());
        someHashesFailed = true;
    }
    else {
        Debug.WriteLine("hash verified for " + filename + "(" + computedHashHex + ")");
    }

    i = i + 1;
}

if (someHashesFailed == true) {
    Debug.WriteLine("Some hashes failed.");
    return;
}

// Let's verify the signature..
// First get the signature.
ent = zip.GetEntryByName("signature");
if (zip.LastMethodSuccess == false) {
    Debug.WriteLine("signature not found in the pkpass file.");
    return;
}

Chilkat.BinData bdSignature = new Chilkat.BinData();
success = await ent.UnzipToBdAsync(bdSignature);

// Show the contents of the signature in base64 encoding.
Debug.WriteLine("Signature:");
Debug.WriteLine(bdSignature.GetEncoded("base64_mime"));
Debug.WriteLine("----");

// Verify the signature against the manifest.json
crypt.EncodingMode = "base64";
bool verified = crypt.VerifyBdENC(bdManifest,bdSignature.GetEncoded("base64"));
if (verified == false) {
    Debug.WriteLine(crypt.LastErrorText);
}

Debug.WriteLine("signature verified = " + Convert.ToString(verified));