(VBScript) ECDSA Sign and Verify Data using Different Hash Algorithms

Demonstrates how to create ECDSA signatures on data using different hash algorithms.

Note: This example requires Chilkat v9.5.0.85 or greater because the SignBd and VerifyBd methods were added in v9.5.0.85.

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

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

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

' First load an ECDSA private key to be used for signing.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PrivateKey")
set privKey = CreateObject("Chilkat.PrivateKey")
success = privKey.LoadEncryptedPemFile("qa_data/ecc/secp256r1-key-pkcs8-secret.pem","secret")
If (success = 0) Then
    outFile.WriteLine(privKey.LastErrorText)
    WScript.Quit
End If

' Load some data to be signed.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.BinData")
set bd = CreateObject("Chilkat.BinData")
success = bd.LoadFile("qa_data/hamlet.xml")
If (success = 0) Then
    outFile.WriteLine("Failed to load file to be hashed.")
    WScript.Quit
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Ecc")
set ecdsa = CreateObject("Chilkat.Ecc")
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Prng")
set prng = CreateObject("Chilkat.Prng")

' Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
outFile.WriteLine("ECDSA signing the sha256 hash of the data...")
sig = ecdsa.SignBd(bd,"sha256","base64",privKey,prng)
outFile.WriteLine("sig = " & sig)

' Verify the signature against the original data.
' (We must use the same hash algorithm that was used when signing.)

' Load the public key that corresponds to the private key used for signing.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PublicKey")
set pubKey = CreateObject("Chilkat.PublicKey")
success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pub.pem")
If (success = 0) Then
    outFile.WriteLine(pubKey.LastErrorText)
    WScript.Quit
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Ecc")
set ecc2 = CreateObject("Chilkat.Ecc")
result = ecc2.VerifyBd(bd,"sha256",sig,"base64",pubKey)
If (result <> 1) Then
    outFile.WriteLine(ecc2.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("Verified!")

' ----------------------------------------------------------------------------------------
' Let's do the same thing, but with sha384 hashing...

outFile.WriteLine("--------------------------------------------")
outFile.WriteLine("ECDSA signing the sha384 hash of the data...")

sig = ecdsa.SignBd(bd,"sha384","base64",privKey,prng)
outFile.WriteLine("sig = " & sig)

result = ecc2.VerifyBd(bd,"sha384",sig,"base64",pubKey)
If (result <> 1) Then
    outFile.WriteLine(ecc2.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("Verified!")

outFile.Close