(Classic ASP) RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature.

Note: This example requires Chilkat v11.0.0 or greater.

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ActiveX for 32-bit and 64-bit Windows

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

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

set privKey = Server.CreateObject("Chilkat.PrivateKey")

' Load the private key from an RSA .key file:
success = privKey.LoadPemFile("privateKey.key")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( privKey.LastErrorText) & "</pre>"
    Response.End
End If

set rsa = Server.CreateObject("Chilkat.Rsa")

' Import the private key into the RSA component:
success = rsa.UsePrivateKey(privKey)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( rsa.LastErrorText) & "</pre>"
    Response.End
End If

' Create the signature as a hex string:
rsa.EncodingMode = "hex"

strData = "This is the string to be signed."

' Sign the string using the sha256 hash algorithm.
' Other valid choices are "md2", "sha1", "sha384",
' "sha512", and "md5".
hexSig = rsa.SignStringENC(strData,"sha256")

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

' Load a digital certificate from a .cer file:
set cert = Server.CreateObject("Chilkat.Cert")

success = cert.LoadFromFile("myCert.cer")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( cert.LastErrorText) & "</pre>"
    Response.End
End If

set pubKey = Server.CreateObject("Chilkat.PublicKey")
success = cert.GetPublicKey(pubKey)

' Now verify using a new instance of the RSA object:
set rsa2 = Server.CreateObject("Chilkat.Rsa")

' Import the public key into the RSA object:
success = rsa2.UsePublicKey(pubKey)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( rsa2.LastErrorText) & "</pre>"
    Response.End
End If

' The signature is a hex string, so make sure the EncodingMode is correct:
rsa2.EncodingMode = "hex"

' Verify the signature:
success = rsa2.VerifyStringENC(strData,"sha256",hexSig)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( rsa2.LastErrorText) & "</pre>"
    Response.End
End If

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

%>
</body>
</html>