(Visual FoxPro) 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.

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

LOCAL loJwt
LOCAL lcToken
LOCAL lnSigVerified
LOCAL lnLeeway
LOCAL lnBTimeValid
LOCAL lcPayload
LOCAL loJson
LOCAL lnSuccess
LOCAL lcJoseHeader

* 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.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jwt')
loJwt = CreateObject('Chilkat.Jwt')

lcToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

* First verify the signature.
* The password used to create this JWT was "secret".
lnSigVerified = loJwt.VerifyJwt(lcToken,"secret")
? "with correct password: " + STR(lnSigVerified)

* Now try with a different password:
lnSigVerified = loJwt.VerifyJwt(lcToken,"secret2")
? "with incorrect password " + STR(lnSigVerified)

* 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.
lnLeeway = 60
lnBTimeValid = loJwt.IsTimeValid(lcToken,lnLeeway)
? "time constraints valid: " + STR(lnBTimeValid)

* Now let's recover the original claims JSON (the payload).
lcPayload = loJwt.GetPayload(lcToken)
* The payload will likely be in compact form:
? lcPayload

* We can format for human viewing by loading it into Chilkat's JSON object
* and emit.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
lnSuccess = loJson.Load(lcPayload)
loJson.EmitCompact = 0
? loJson.Emit()

* We can recover the original JOSE header in the same way:
lcJoseHeader = loJwt.GetHeader(lcToken)
* The payload will likely be in compact form:
? lcJoseHeader

* We can format for human viewing by loading it into Chilkat's JSON object
* and emit.
lnSuccess = loJson.Load(lcJoseHeader)
loJson.EmitCompact = 0
? loJson.Emit()

RELEASE loJwt
RELEASE loJson