(AutoIt) Extract PKCS7 Signature Digest

Demonstrates how to extract a signature digest from a PKCS7 signature.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

; This example requires the Chilkat Crypt API to have been previously unlocked.
; See Unlock Chilkat Crypt for sample code.

$oCrypt = ObjCreate("Chilkat.Crypt2")

Local $sP7mFile = "qa_data/p7m/test.pdf.p7m"
Local $sOutPath = "qa_output/test.pdf"

; First let's see if this .p7m signature can be verified, and the original file extracted.
Local $bVerified = $oCrypt.VerifyP7M($sP7mFile,$sOutPath)
If ($bVerified <> True) Then
    ConsoleWrite($oCrypt.LastErrorText & @CRLF)
    Exit
EndIf

; How many signers?
; (The NumSignerCerts property is set whenever a signature is verified.)
ConsoleWrite("Num Signers: " & $oCrypt.NumSignerCerts & @CRLF)

; Load the .p7m into memory...
$oPkcs7Data = ObjCreate("Chilkat.BinData")
$oPkcs7Data.LoadFile($sP7mFile)

; Check to see if this .p7m contains the binary bytes, or if it's
; already base64 encoded.  Get the 1st two bytes.  If the first two 
; bytes are the us-ascii values "MI", then we have base64.
$oSbBase64 = ObjCreate("Chilkat.StringBuilder")
Local $sHexStr = $oPkcs7Data.GetEncodedChunk(0,2,"hex")
$oSbBase64.Append($sHexStr)

Local $bHaveBase64 = False
If ($oSbBase64.ContentsEqual("4D49",True) = True) Then
    $bHaveBase64 = True
    $oSbBase64.Clear 
    $oSbBase64.AppendBd($oPkcs7Data,"utf-8",0,0)
EndIf

; Get each signer's signature digest.
$oCrypt.EncodingMode = "base64"
Local $i = 0
Local $sDigest
While $i < $oCrypt.NumSignerCerts
    If ($bHaveBase64) Then
        $sDigest = $oCrypt.Pkcs7ExtractDigest($i,$oSbBase64.GetAsString())
    Else
        $sDigest = $oCrypt.Pkcs7ExtractDigest($i,$oPkcs7Data.GetEncoded("base64"))
    EndIf

    If ($oCrypt.LastMethodSuccess <> True) Then
        ConsoleWrite($oCrypt.LastErrorText & @CRLF)
        Exit
    EndIf

    ConsoleWrite("Signer " & ($i + 1) & " digest = " & $sDigest & @CRLF)
    $i = $i + 1
Wend