(Visual FoxPro) 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 ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loCrypt
LOCAL loZip
LOCAL lnSuccess
LOCAL loEnt
LOCAL loBdManifest
LOCAL loJson
LOCAL lnSomeHashesFailed
LOCAL lcFilename
LOCAL loSbHashHex
LOCAL loBdFileData
LOCAL lnNumMembers
LOCAL i
LOCAL lcComputedHashHex
LOCAL loBdSignature
LOCAL lnVerified

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Crypt2')
loCrypt = CreateObject('Chilkat.Crypt2')
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Zip')
loZip = CreateObject('Chilkat.Zip')

lnSuccess = loZip.OpenZip("qa_data/pkpass/invalid.pkpass")
IF (lnSuccess = 0) THEN
    ? loZip.LastErrorText
    RELEASE loCrypt
    RELEASE loZip
    CANCEL
ENDIF

* 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"
* }

loEnt = loZip.GetEntryByName("manifest.json")
IF (loZip.LastMethodSuccess = 0) THEN
    ? "manifest.json entry not found."
    RELEASE loCrypt
    RELEASE loZip
    CANCEL
ENDIF

* Get the exact content of the manifest.json for later signature verification.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.BinData')
loBdManifest = CreateObject('Chilkat.BinData')
lnSuccess = loEnt.UnzipToBd(loBdManifest)

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
loJson.EmitCompact = 0
loJson.Load(loEnt.UnzipToString(0,"utf-8"))
? loJson.Emit()

RELEASE loEnt

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

lnSomeHashesFailed = 0

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbHashHex = CreateObject('Chilkat.StringBuilder')
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.BinData')
loBdFileData = CreateObject('Chilkat.BinData')
lnNumMembers = loJson.Size
i = 0
DO WHILE i < lnNumMembers
    lcFilename = loJson.NameAt(i)
    loSbHashHex.Clear()
    loSbHashHex.Append(loJson.StringAt(i))

    loEnt = loZip.GetEntryByName(lcFilename)
    IF (loZip.LastMethodSuccess = 0) THEN
        ? lcFilename + " not found in the pkpass file."
        RELEASE loCrypt
        RELEASE loZip
        RELEASE loBdManifest
        RELEASE loJson
        RELEASE loSbHashHex
        RELEASE loBdFileData
        CANCEL
    ENDIF

    * Get the data for this file.
    loBdFileData.Clear()
    lnSuccess = loEnt.UnzipToBd(loBdFileData)

    lcComputedHashHex = loCrypt.HashBdENC(loBdFileData)
    IF (loSbHashHex.ContentsEqual(lcComputedHashHex,0) = 0) THEN
        ? "Computed hash does not match stored hash for " + lcFilename
        ? "  computed: " + lcComputedHashHex
        ? "  stored:   " + loSbHashHex.GetAsString()
        lnSomeHashesFailed = 1
    ELSE
        ? "hash verified for " + lcFilename + "(" + lcComputedHashHex + ")"
    ENDIF

    RELEASE loEnt

    i = i + 1
ENDDO

IF (lnSomeHashesFailed = 1) THEN
    ? "Some hashes failed."
    RELEASE loCrypt
    RELEASE loZip
    RELEASE loBdManifest
    RELEASE loJson
    RELEASE loSbHashHex
    RELEASE loBdFileData
    CANCEL
ENDIF

* Let's verify the signature..
* First get the signature.
loEnt = loZip.GetEntryByName("signature")
IF (loZip.LastMethodSuccess = 0) THEN
    ? "signature not found in the pkpass file."
    RELEASE loCrypt
    RELEASE loZip
    RELEASE loBdManifest
    RELEASE loJson
    RELEASE loSbHashHex
    RELEASE loBdFileData
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.BinData')
loBdSignature = CreateObject('Chilkat.BinData')
lnSuccess = loEnt.UnzipToBd(loBdSignature)
RELEASE loEnt

* Show the contents of the signature in base64 encoding.
? "Signature:"
? loBdSignature.GetEncoded("base64_mime")
? "----"

* Verify the signature against the manifest.json
loCrypt.EncodingMode = "base64"
lnVerified = loCrypt.VerifyBdENC(loBdManifest,loBdSignature.GetEncoded("base64"))
IF (lnVerified = 0) THEN
    ? loCrypt.LastErrorText
ENDIF

? "signature verified = " + STR(lnVerified)

RELEASE loCrypt
RELEASE loZip
RELEASE loBdManifest
RELEASE loJson
RELEASE loSbHashHex
RELEASE loBdFileData
RELEASE loBdSignature