(PowerShell) 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 .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

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

$crypt = New-Object Chilkat.Crypt2
$zip = New-Object Chilkat.Zip

$success = $zip.OpenZip("qa_data/pkpass/invalid.pkpass")
if ($success -eq $false) {
    $($zip.LastErrorText)
    exit
}

# 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 = $zip.GetEntryByName("manifest.json")
if ($zip.LastMethodSuccess -eq $false) {
    $("manifest.json entry not found.")
    exit
}

# Get the exact content of the manifest.json for later signature verification.
$bdManifest = New-Object Chilkat.BinData
$success = $ent.UnzipToBd($bdManifest)

$json = New-Object Chilkat.JsonObject
$json.EmitCompact = $false
$json.Load($ent.UnzipToString(0,"utf-8"))
$($json.Emit())

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

$someHashesFailed = $false

$sbHashHex = New-Object Chilkat.StringBuilder
$bdFileData = New-Object Chilkat.BinData
$numMembers = $json.Size
$i = 0
while ($i -lt $numMembers) {
    $filename = $json.NameAt($i)
    $sbHashHex.Clear()
    $sbHashHex.Append($json.StringAt($i))

    $ent = $zip.GetEntryByName($filename)
    if ($zip.LastMethodSuccess -eq $false) {
        $($filename + " not found in the pkpass file.")
        exit
    }

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

    $computedHashHex = $crypt.HashBdENC($bdFileData)
    if ($sbHashHex.ContentsEqual($computedHashHex,$false) -eq $false) {
        $("Computed hash does not match stored hash for " + $filename)
        $("  computed: " + $computedHashHex)
        $("  stored:   " + $sbHashHex.GetAsString())
        $someHashesFailed = $true
    }
    else {
        $("hash verified for " + $filename + "(" + $computedHashHex + ")")
    }

    $i = $i + 1
}

if ($someHashesFailed -eq $true) {
    $("Some hashes failed.")
    exit
}

# Let's verify the signature..
# First get the signature.
$ent = $zip.GetEntryByName("signature")
if ($zip.LastMethodSuccess -eq $false) {
    $("signature not found in the pkpass file.")
    exit
}

$bdSignature = New-Object Chilkat.BinData
$success = $ent.UnzipToBd($bdSignature)

# Show the contents of the signature in base64 encoding.
$("Signature:")
$($bdSignature.GetEncoded("base64_mime"))
$("----")

# Verify the signature against the manifest.json
$crypt.EncodingMode = "base64"
$verified = $crypt.VerifyBdENC($bdManifest,$bdSignature.GetEncoded("base64"))
if ($verified -eq $false) {
    $($crypt.LastErrorText)
}

$("signature verified = " + $verified)