(AutoIt) Create ECSDA Signature using Raw r and s Format (not ASN.1)

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Demonstrates how to create an ECDSA signature using the raw r/s format.

ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:

(a) Concatenating the raw byte array of r and s
(b) Encoding both into a structured ASN.1 / DER sequence.

This example demonstrates how to create a signature that is a byte array of r and s concatenated.

Note: This example requires Chilkat v9.5.0.97 or greater.

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

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

; To create an ECDSA signature, the data first needs to be hashed.  Then the hash
; is signed.

$oSb = ObjCreate("Chilkat.StringBuilder")
$oSb.Append("The quick brown fox jumps over the lazy dog")
Local $sHash = $oSb.GetHash("sha256","base64","utf-8")

; Load the ECDSA key to be used for signing.
$oPrivKey = ObjCreate("Chilkat.PrivateKey")
Local $bSuccess = $oPrivKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
If ($bSuccess <> True) Then
    ConsoleWrite($oPrivKey.LastErrorText & @CRLF)
    Exit
EndIf

$oPrng = ObjCreate("Chilkat.Prng")
$oEcdsa = ObjCreate("Chilkat.Ecc")

; Produce a signature that is not ASN.1, but is instead the concatenation
; of the raw r and s signature parts.
; This feature was added in Chilkat v9.5.0.97
$oEcdsa.AsnFormat = False

Local $sEcdsaSigBase64 = $oEcdsa.SignHashENC($sHash,"base64",$oPrivKey,$oPrng)
If ($oEcdsa.LastMethodSuccess <> True) Then
    ConsoleWrite($oEcdsa.LastErrorText & @CRLF)
    Exit
EndIf

ConsoleWrite("ECDSA signature = " & $sEcdsaSigBase64 & @CRLF)

; -----------------------------------------------------------
; Now let's verify the signature using the public key.

$oPubKey = ObjCreate("Chilkat.PublicKey")
$bSuccess = $oPubKey.LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem")
If ($bSuccess <> True) Then
    ConsoleWrite($oPubKey.LastErrorText & @CRLF)
    Exit
EndIf

; Note: When verifying, Chilkat will auto-detect the format for both kinds of ECDSA signatures (ASN.1 or binary r+s)
Local $iResult = $oEcdsa.VerifyHashENC($sHash,$sEcdsaSigBase64,"base64",$oPubKey)
If ($iResult = 1) Then
    ConsoleWrite("Signature is valid." & @CRLF)
    Exit
EndIf

If ($iResult = 0) Then
    ConsoleWrite("Signature is invalid." & @CRLF)
    Exit
EndIf

If ($iResult < 0) Then
    ConsoleWrite($oEcdsa.LastErrorText & @CRLF)
    ConsoleWrite("The VerifyHashENC method call failed." & @CRLF)
    Exit
EndIf