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Verify JWT Using HS256, HS384, or HS512

See more JSON Web Token (JWT) Examples

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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Local $bSuccess = False

; 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.

$oJwt = ObjCreate("Chilkat.Jwt")

Local $sToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

; First verify the signature.
; The password used to create this JWT was "secret".
Local $bSigVerified = $oJwt.VerifyJwt($sToken,"secret")
ConsoleWrite("with correct password: " & $bSigVerified & @CRLF)

; Now try with a different password:
$bSigVerified = $oJwt.VerifyJwt($sToken,"secret2")
ConsoleWrite("with incorrect password " & $bSigVerified & @CRLF)

; 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.
Local $iLeeway = 60
Local $bTimeValid = $oJwt.IsTimeValid($sToken,$iLeeway)
ConsoleWrite("time constraints valid: " & $bTimeValid & @CRLF)

; Now let's recover the original claims JSON (the payload).
Local $sPayload = $oJwt.GetPayload($sToken)
; The payload will likely be in compact form:
ConsoleWrite($sPayload & @CRLF)

; We can format for human viewing by loading it into Chilkat's JSON object
; and emit.
$oJson = ObjCreate("Chilkat.JsonObject")
$bSuccess = $oJson.Load($sPayload)
$oJson.EmitCompact = False
ConsoleWrite($oJson.Emit() & @CRLF)

; We can recover the original JOSE header in the same way:
Local $sJoseHeader = $oJwt.GetHeader($sToken)
; The payload will likely be in compact form:
ConsoleWrite($sJoseHeader & @CRLF)

; We can format for human viewing by loading it into Chilkat's JSON object
; and emit.
$bSuccess = $oJson.Load($sJoseHeader)
$oJson.EmitCompact = False
ConsoleWrite($oJson.Emit() & @CRLF)