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ECDSA Sign Data and Verify Signature

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Demonstrates using the Elliptic Curve Digital Signature Algorithm to hash data and sign it. Also demonstrates how to verify the ECDSA signature. AutoIt

Local $bSuccess = False

; 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.

; Use Chilkat Crypt2 to generate a hash for any of the following
; hash algorithms: SHA256, SHA384, SHA512, SHA1, MD5, MD2, HAVAL, RIPEMD128/160/256/320

$oCrypt = ObjCreate("Chilkat.Crypt2")
$oCrypt.HashAlgorithm = "SHA256"
$oCrypt.Charset = "utf-8"
$oCrypt.EncodingMode = "base64"

; Hash a string.
Local $sHash1 = $oCrypt.HashStringENC("The quick brown fox jumps over the lazy dog")
ConsoleWrite("hash1 = " & $sHash1 & @CRLF)

; Or hash a file..
Local $sHash2 = $oCrypt.HashFileENC("qa_data/hamlet.xml")
ConsoleWrite("hash2 = " & $sHash2 & @CRLF)

; (The Crypt2 API provides many other ways to hash data..)

; -----------------------------------------------------------
; An ECDSA private key is used for signing.  The public key is for signature verification.
; Load our ECC private key.
; Our private key file contains this:

; 	// -----BEGIN PRIVATE KEY-----
; 	MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg3J8q/24D1sEKGdP9
; 	72MGYElLGpw/a56Y3t6pfON3uhShRANCAATlSmoizyhAwoYZAOuFBATl07/1RR54
; 	a1Dzfm16grxJe666AGKR+bSs24hk7TEpaeCTvT8YOOM3l+xKFg7zq6Q9
; 	-----END PRIVATE KEY-----

$oPrivKey = ObjCreate("Chilkat.PrivateKey")
$bSuccess = $oPrivKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
If ($bSuccess <> True) Then
    ConsoleWrite($oPrivKey.LastErrorText & @CRLF)
    Exit
EndIf

; We'll need a PRNG source for random number generation.
; Use Chilkat's PRNG (for the Fortuna PRNG algorithm).
$oPrng = ObjCreate("Chilkat.Prng")

; Sign the hash..
$oEcdsa = ObjCreate("Chilkat.Ecc")
Local $sEcdsaSigBase64 = $oEcdsa.SignHashENC($sHash1,"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

Local $iResult = $oEcdsa.VerifyHashENC($sHash1,$sEcdsaSigBase64,"base64",$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