(MFC) 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 C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkCrypt2.h>
#include <CkZip.h>
#include <CkZipEntry.h>
#include <CkBinData.h>
#include <CkJsonObject.h>
#include <CkStringBuilder.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkCrypt2 crypt;
    CkZip zip;

    bool success = zip.OpenZip("qa_data/pkpass/invalid.pkpass");
    if (success == false) {
        strOut.append(zip.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        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"
    // }

    CkZipEntry *ent = zip.GetEntryByName("manifest.json");
    if (zip.get_LastMethodSuccess() == false) {
        strOut.append("manifest.json entry not found.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Get the exact content of the manifest.json for later signature verification.
    CkBinData bdManifest;
    success = ent->UnzipToBd(bdManifest);

    CkJsonObject json;
    json.put_EmitCompact(false);
    json.Load(ent->unzipToString(0,"utf-8"));
    strOut.append(json.emit());
    strOut.append("\r\n");

    delete ent;

    // For each file in the JSON, get the filename and hex hash value.
    crypt.put_EncodingMode("hexlower");
    crypt.put_HashAlgorithm("sha1");

    bool someHashesFailed = false;
    const char *filename = 0;
    CkStringBuilder sbHashHex;
    CkBinData bdFileData;
    int numMembers = json.get_Size();
    int i = 0;
    while (i < numMembers) {
        filename = json.nameAt(i);
        sbHashHex.Clear();
        sbHashHex.Append(json.stringAt(i));

        ent = zip.GetEntryByName(filename);
        if (zip.get_LastMethodSuccess() == false) {
            strOut.append(filename);
            strOut.append(" not found in the pkpass file.");
            strOut.append("\r\n");
            SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
            return;
        }

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

        const char *computedHashHex = crypt.hashBdENC(bdFileData);
        if (sbHashHex.ContentsEqual(computedHashHex,false) == false) {
            strOut.append("Computed hash does not match stored hash for ");
            strOut.append(filename);
            strOut.append("\r\n");
            strOut.append("  computed: ");
            strOut.append(computedHashHex);
            strOut.append("\r\n");
            strOut.append("  stored:   ");
            strOut.append(sbHashHex.getAsString());
            strOut.append("\r\n");
            someHashesFailed = true;
        }
        else {
            strOut.append("hash verified for ");
            strOut.append(filename);
            strOut.append("(");
            strOut.append(computedHashHex);
            strOut.append(")");
            strOut.append("\r\n");
        }

        delete ent;

        i = i + 1;
    }

    if (someHashesFailed == true) {
        strOut.append("Some hashes failed.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Let's verify the signature..
    // First get the signature.
    ent = zip.GetEntryByName("signature");
    if (zip.get_LastMethodSuccess() == false) {
        strOut.append("signature not found in the pkpass file.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    CkBinData bdSignature;
    success = ent->UnzipToBd(bdSignature);
    delete ent;

    // Show the contents of the signature in base64 encoding.
    strOut.append("Signature:");
    strOut.append("\r\n");
    strOut.append(bdSignature.getEncoded("base64_mime"));
    strOut.append("\r\n");
    strOut.append("----");
    strOut.append("\r\n");

    // Verify the signature against the manifest.json
    crypt.put_EncodingMode("base64");
    bool verified = crypt.VerifyBdENC(bdManifest,bdSignature.getEncoded("base64"));
    if (verified == false) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
    }

    strOut.append("signature verified = ");
    strOut.appendInt(verified);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }