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Verfies an RSA Signature

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Verifies an RSA signature against the original data.

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Local $bSuccess = False

; The following data was signed by the following example:
; RSA Sign using a Private Key on a USB Token or Smartcard
$oBd = ObjCreate("Chilkat.BinData")
Local $i
For $i = 0 To 100
    $oBd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex")
Next

; Load the signature
$oBdSig = ObjCreate("Chilkat.BinData")
$bSuccess = $oBdSig.LoadFile("rsaSignatures/test1.sig")
If ($bSuccess = False) Then
    ConsoleWrite("Failed to load the RSA signature" & @CRLF)
    Exit
EndIf

; Get the public key to be used for signature verification.
$oPubKey = ObjCreate("Chilkat.PublicKey")
$bSuccess = $oPubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
If ($bSuccess = False) Then
    ConsoleWrite($oPubKey.LastErrorText & @CRLF)
    Exit
EndIf

$oRsa = ObjCreate("Chilkat.Rsa")
$bSuccess = $oRsa.UsePublicKey($oPubKey)
If ($bSuccess = False) Then
    ConsoleWrite($oRsa.LastErrorText & @CRLF)
    Exit
EndIf

; Verify the hash of the data against the signature.
; We pass in the original data.  Internally, the hash is generated
; and used to validate the signature.
; Validating the RSA signature means two things:  
; (1) the original data is exactly what was signed, and 
; (2) it was signed by the owner of the RSA private key.
$bSuccess = $oRsa.VerifyBd($oBd,"sha256",$oBdSig)

If ($bSuccess = False) Then
    ConsoleWrite($oRsa.LastErrorText & @CRLF)
    ConsoleWrite("Signature invalid." & @CRLF)
Else
    ConsoleWrite("Signature valid." & @CRLF)
EndIf