(PowerBuilder) 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

integer li_rc
oleobject loo_Crypt
string ls_P7mFile
string ls_OutPath
integer li_Verified
oleobject loo_Pkcs7Data
oleobject loo_SbBase64
string ls_HexStr
integer li_BHaveBase64
integer i
string ls_Digest

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

loo_Crypt = create oleobject
// Use "Chilkat_9_5_0.Crypt2" for versions of Chilkat < 10.0.0
li_rc = loo_Crypt.ConnectToNewObject("Chilkat.Crypt2")
if li_rc < 0 then
    destroy loo_Crypt
    MessageBox("Error","Connecting to COM object failed")
    return
end if

ls_P7mFile = "qa_data/p7m/test.pdf.p7m"
ls_OutPath = "qa_output/test.pdf"

// First let's see if this .p7m signature can be verified, and the original file extracted.
li_Verified = loo_Crypt.VerifyP7M(ls_P7mFile,ls_OutPath)
if li_Verified <> 1 then
    Write-Debug loo_Crypt.LastErrorText
    destroy loo_Crypt
    return
end if

// How many signers?
// (The NumSignerCerts property is set whenever a signature is verified.)
Write-Debug "Num Signers: " + string(loo_Crypt.NumSignerCerts)

// Load the .p7m into memory...
loo_Pkcs7Data = create oleobject
// Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
li_rc = loo_Pkcs7Data.ConnectToNewObject("Chilkat.BinData")

loo_Pkcs7Data.LoadFile(ls_P7mFile)

// 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.
loo_SbBase64 = create oleobject
// Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
li_rc = loo_SbBase64.ConnectToNewObject("Chilkat.StringBuilder")

ls_HexStr = loo_Pkcs7Data.GetEncodedChunk(0,2,"hex")
loo_SbBase64.Append(ls_HexStr)

li_BHaveBase64 = 0
if loo_SbBase64.ContentsEqual("4D49",1) = 1 then
    li_BHaveBase64 = 1
    loo_SbBase64.Clear()
    loo_SbBase64.AppendBd(loo_Pkcs7Data,"utf-8",0,0)
end if

// Get each signer's signature digest.
loo_Crypt.EncodingMode = "base64"
i = 0

do while i < loo_Crypt.NumSignerCerts
    if li_BHaveBase64 then
        ls_Digest = loo_Crypt.Pkcs7ExtractDigest(i,loo_SbBase64.GetAsString())
    else
        ls_Digest = loo_Crypt.Pkcs7ExtractDigest(i,loo_Pkcs7Data.GetEncoded("base64"))
    end if

    if loo_Crypt.LastMethodSuccess <> 1 then
        Write-Debug loo_Crypt.LastErrorText
        destroy loo_Crypt
        destroy loo_Pkcs7Data
        destroy loo_SbBase64
        return
    end if

    Write-Debug "Signer " + string(i + 1) + " digest = " + ls_Digest
    i = i + 1
loop


destroy loo_Crypt
destroy loo_Pkcs7Data
destroy loo_SbBase64