Xojo Plugin

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. Xojo Plugin

Dim success As Boolean
success = False

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

Dim crypt As New Chilkat.Crypt2
Dim zip As New Chilkat.Zip

success = zip.OpenZip("qa_data/pkpass/invalid.pkpass")
If (success = False) Then
    System.DebugLog(zip.LastErrorText)
    Return
End If

// 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"
// }

Dim ent As New Chilkat.ZipEntry
success = zip.EntryOf("manifest.json",ent)
If (success = False) Then
    System.DebugLog(zip.LastErrorText)
    Return
End If

// Get the exact content of the manifest.json for later signature verification.
Dim bdManifest As New Chilkat.BinData
success = ent.UnzipToBd(bdManifest)

Dim json As New Chilkat.JsonObject
json.EmitCompact = False
success = json.Load(ent.UnzipToString(0,"utf-8"))
System.DebugLog(json.Emit())

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

Dim someHashesFailed As Boolean
someHashesFailed = False
Dim filename As String
Dim sbHashHex As New Chilkat.StringBuilder
Dim bdFileData As New Chilkat.BinData
Dim numMembers As Int32
numMembers = json.Size
Dim i As Int32
i = 0
While i < numMembers
    filename = json.NameAt(i)
    sbHashHex.Clear 
    success = sbHashHex.Append(json.StringAt(i))

    success = zip.EntryOf(filename,ent)
    If (success = False) Then
        System.DebugLog(zip.LastErrorText)
        Return
    End If

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

    Dim computedHashHex As String
    computedHashHex = crypt.HashBdENC(bdFileData)
    If (sbHashHex.ContentsEqual(computedHashHex,False) = False) Then
        System.DebugLog("Computed hash does not match stored hash for " + filename)
        System.DebugLog("  computed: " + computedHashHex)
        System.DebugLog("  stored:   " + sbHashHex.GetAsString())
        someHashesFailed = True
    Else
        System.DebugLog("hash verified for " + filename + "(" + computedHashHex + ")")
    End If

    i = i + 1
Wend

If (someHashesFailed = True) Then
    System.DebugLog("Some hashes failed.")
    Return
End If

// Let's verify the signature..
// First get the signature.
success = zip.EntryOf("signature",ent)
If (success = False) Then
    System.DebugLog(zip.LastErrorText)
    Return
End If

Dim bdSignature As New Chilkat.BinData
success = ent.UnzipToBd(bdSignature)

// Show the contents of the signature in base64 encoding.
System.DebugLog("Signature:")
System.DebugLog(bdSignature.GetEncoded("base64_mime"))
System.DebugLog("----")

// Verify the signature against the manifest.json
crypt.EncodingMode = "base64"
Dim verified As Boolean
verified = crypt.VerifyBdENC(bdManifest,bdSignature.GetEncoded("base64"))
If (verified = False) Then
    System.DebugLog(crypt.LastErrorText)
End If

System.DebugLog("signature verified = " + Str(verified))