Classic ASP

Verify JWT Using HS256, HS384, or HS512

Demonstrates how to verify a JWT that was signed using HS256, HS384, or HS512. (HS256 is JWT's acronym for HMAC-SHA256.)

This example verifies the signature. It also does the following:

Checks to see if the time constraints ("nbf" and "exp") are valid.
Recovers the original JOSE header.
Recovers the original claims JSON.

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Classic ASP

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

' Demonstrates how to verify an HMAC JWT using a shared secret (password).

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

set jwt = Server.CreateObject("Chilkat.Jwt")

token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

' First verify the signature.
' The password used to create this JWT was "secret".
sigVerified = jwt.VerifyJwt(token,"secret")
Response.Write "<pre>" & Server.HTMLEncode( "with correct password: " & sigVerified) & "</pre>"

' Now try with a different password:
sigVerified = jwt.VerifyJwt(token,"secret2")
Response.Write "<pre>" & Server.HTMLEncode( "with incorrect password " & sigVerified) & "</pre>"

' Let's see if the time constraints, if any, are valid.
' The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
' If the current system time is before the "nbf" time, or after the "exp" time,
' then IsTimeValid will return false/0.
' Also, we'll allow a leeway of 60 seconds to account for any clock skew.
' Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
leeway = 60
bTimeValid = jwt.IsTimeValid(token,leeway)
Response.Write "<pre>" & Server.HTMLEncode( "time constraints valid: " & bTimeValid) & "</pre>"

' Now let's recover the original claims JSON (the payload).
payload = jwt.GetPayload(token)
' The payload will likely be in compact form:
Response.Write "<pre>" & Server.HTMLEncode( payload) & "</pre>"

' We can format for human viewing by loading it into Chilkat's JSON object
' and emit.
set json = Server.CreateObject("Chilkat.JsonObject")
success = json.Load(payload)
json.EmitCompact = 0
Response.Write "<pre>" & Server.HTMLEncode( json.Emit()) & "</pre>"

' We can recover the original JOSE header in the same way:
joseHeader = jwt.GetHeader(token)
' The payload will likely be in compact form:
Response.Write "<pre>" & Server.HTMLEncode( joseHeader) & "</pre>"

' We can format for human viewing by loading it into Chilkat's JSON object
' and emit.
success = json.Load(joseHeader)
json.EmitCompact = 0
Response.Write "<pre>" & Server.HTMLEncode( json.Emit()) & "</pre>"

%>
</body>
</html>