(C) 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.

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#include <C_CkCrypt2.h>
#include <C_CkZip.h>
#include <C_CkZipEntry.h>
#include <C_CkBinData.h>
#include <C_CkJsonObject.h>
#include <C_CkStringBuilder.h>

void ChilkatSample(void)
    {
    HCkCrypt2 crypt;
    HCkZip zip;
    BOOL success;
    HCkZipEntry ent;
    HCkBinData bdManifest;
    HCkJsonObject json;
    BOOL someHashesFailed;
    const char *filename;
    HCkStringBuilder sbHashHex;
    HCkBinData bdFileData;
    int numMembers;
    int i;
    const char *computedHashHex;
    HCkBinData bdSignature;
    BOOL verified;

    // 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) {
        printf("%s\n",CkZip_lastErrorText(zip));
        CkCrypt2_Dispose(crypt);
        CkZip_Dispose(zip);
        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"
    // }

    ent = CkZip_GetEntryByName(zip,"manifest.json");
    if (CkZip_getLastMethodSuccess(zip) == FALSE) {
        printf("manifest.json entry not found.\n");
        CkCrypt2_Dispose(crypt);
        CkZip_Dispose(zip);
        return;
    }

    // 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"));
    printf("%s\n",CkJsonObject_emit(json));

    CkZipEntry_Dispose(ent);

    // 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) {
        filename = CkJsonObject_nameAt(json,i);
        CkStringBuilder_Clear(sbHashHex);
        CkStringBuilder_Append(sbHashHex,CkJsonObject_stringAt(json,i));

        ent = CkZip_GetEntryByName(zip,filename);
        if (CkZip_getLastMethodSuccess(zip) == FALSE) {
            printf("%s not found in the pkpass file.\n",filename);
            CkCrypt2_Dispose(crypt);
            CkZip_Dispose(zip);
            CkBinData_Dispose(bdManifest);
            CkJsonObject_Dispose(json);
            CkStringBuilder_Dispose(sbHashHex);
            CkBinData_Dispose(bdFileData);
            return;
        }

        // 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) {
            printf("Computed hash does not match stored hash for %s\n",filename);
            printf("  computed: %s\n",computedHashHex);
            printf("  stored:   %s\n",CkStringBuilder_getAsString(sbHashHex));
            someHashesFailed = TRUE;
        }
        else {
            printf("hash verified for %s(%s)\n",filename,computedHashHex);
        }

        CkZipEntry_Dispose(ent);

        i = i + 1;
    }

    if (someHashesFailed == TRUE) {
        printf("Some hashes failed.\n");
        CkCrypt2_Dispose(crypt);
        CkZip_Dispose(zip);
        CkBinData_Dispose(bdManifest);
        CkJsonObject_Dispose(json);
        CkStringBuilder_Dispose(sbHashHex);
        CkBinData_Dispose(bdFileData);
        return;
    }

    // Let's verify the signature..
    // First get the signature.
    ent = CkZip_GetEntryByName(zip,"signature");
    if (CkZip_getLastMethodSuccess(zip) == FALSE) {
        printf("signature not found in the pkpass file.\n");
        CkCrypt2_Dispose(crypt);
        CkZip_Dispose(zip);
        CkBinData_Dispose(bdManifest);
        CkJsonObject_Dispose(json);
        CkStringBuilder_Dispose(sbHashHex);
        CkBinData_Dispose(bdFileData);
        return;
    }

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

    // Show the contents of the signature in base64 encoding.
    printf("Signature:\n");
    printf("%s\n",CkBinData_getEncoded(bdSignature,"base64_mime"));
    printf("----\n");

    // Verify the signature against the manifest.json
    CkCrypt2_putEncodingMode(crypt,"base64");
    verified = CkCrypt2_VerifyBdENC(crypt,bdManifest,CkBinData_getEncoded(bdSignature,"base64"));
    if (verified == FALSE) {
        printf("%s\n",CkCrypt2_lastErrorText(crypt));
    }

    printf("signature verified = %d\n",verified);


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

    }