(Excel) 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.

Download Excel Class Modules Chilkat Excel Class Modules

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

Dim crypt As Chilkat.Crypt2
Set crypt = Chilkat.NewCrypt2
Dim zip As Chilkat.Zip
Set zip = Chilkat.NewZip


success = zip.OpenZip("qa_data/pkpass/invalid.pkpass")
If (success = False) Then
    Debug.Print zip.LastErrorText
    Exit Sub
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"
' }


Set ent = zip.GetEntryByName("manifest.json")
If (zip.LastMethodSuccess = False) Then
    Debug.Print "manifest.json entry not found."
    Exit Sub
End If

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

Dim json As Chilkat.JsonObject
Set json = Chilkat.NewJsonObject
json.EmitCompact = False
Dim success As Boolean
success = json.Load(ent.UnzipToString(0,"utf-8"))
Debug.Print json.Emit()

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


someHashesFailed = False

Dim sbHashHex As Chilkat.StringBuilder
Set sbHashHex = Chilkat.NewStringBuilder
Dim bdFileData As Chilkat.BinData
Set bdFileData = Chilkat.NewBinData

numMembers = json.Size

i = 0
Do While i < numMembers
    filename = json.NameAt(i)
    sbHashHex.Clear 
    success = sbHashHex.Append(json.StringAt(i))

    Set ent = zip.GetEntryByName(filename)
    If (zip.LastMethodSuccess = False) Then
        Debug.Print filename; " not found in the pkpass file."
        Exit Sub
    End If

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


    computedHashHex = crypt.HashBdENC(bdFileData)
    If (sbHashHex.ContentsEqual(computedHashHex,False) = False) Then
        Debug.Print "Computed hash does not match stored hash for "; filename
        Debug.Print "  computed: "; computedHashHex
        Debug.Print "  stored:   "; sbHashHex.GetAsString()
        someHashesFailed = True
    Else
        Debug.Print "hash verified for "; filename; "("; computedHashHex; ")"
    End If

    i = i + 1
Loop

If (someHashesFailed = True) Then
    Debug.Print "Some hashes failed."
    Exit Sub
End If

' Let's verify the signature..
' First get the signature.
Set ent = zip.GetEntryByName("signature")
If (zip.LastMethodSuccess = False) Then
    Debug.Print "signature not found in the pkpass file."
    Exit Sub
End If

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

' Show the contents of the signature in base64 encoding.
Debug.Print "Signature:"
Debug.Print bdSignature.GetEncoded("base64_mime")
Debug.Print "----"

' Verify the signature against the manifest.json
crypt.EncodingMode = "base64"

verified = crypt.VerifyBdENC(bdManifest,bdSignature.GetEncoded("base64"))
If (verified = False) Then
    Debug.Print crypt.LastErrorText
End If

Debug.Print "signature verified = "; verified