(Classic ASP) 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

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
' 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 = Server.CreateObject("Chilkat.PrivateKey")
success = privKey.LoadEncryptedPemFile("qa_data/ecc/secp256r1-key-pkcs8-secret.pem","secret")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( privKey.LastErrorText) & "</pre>"
    Response.End
End If

' Load some data to be signed.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.BinData")
set bd = Server.CreateObject("Chilkat.BinData")
success = bd.LoadFile("qa_data/hamlet.xml")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( "Failed to load file to be hashed.") & "</pre>"
    Response.End
End If

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

' Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
Response.Write "<pre>" & Server.HTMLEncode( "ECDSA signing the sha256 hash of the data...") & "</pre>"
sig = ecdsa.SignBd(bd,"sha256","base64",privKey,prng)
Response.Write "<pre>" & Server.HTMLEncode( "sig = " & sig) & "</pre>"

' 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 = Server.CreateObject("Chilkat.PublicKey")
success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pub.pem")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( pubKey.LastErrorText) & "</pre>"
    Response.End
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Ecc")
set ecc2 = Server.CreateObject("Chilkat.Ecc")
result = ecc2.VerifyBd(bd,"sha256",sig,"base64",pubKey)
If (result <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( ecc2.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "Verified!") & "</pre>"

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

Response.Write "<pre>" & Server.HTMLEncode( "--------------------------------------------") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "ECDSA signing the sha384 hash of the data...") & "</pre>"

sig = ecdsa.SignBd(bd,"sha384","base64",privKey,prng)
Response.Write "<pre>" & Server.HTMLEncode( "sig = " & sig) & "</pre>"

result = ecc2.VerifyBd(bd,"sha384",sig,"base64",pubKey)
If (result <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( ecc2.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "Verified!") & "</pre>"

%>
</body>
</html>