Xbase++

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.

Xbase++

LOCAL nSuccess
LOCAL oJwt
LOCAL cToken
LOCAL nSigVerified
LOCAL nLeeway
LOCAL nBTimeValid
LOCAL cPayload
LOCAL oJson
LOCAL cJoseHeader

nSuccess := 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.

oJwt := CreateObject("Chilkat.Jwt")

cToken := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

//  First verify the signature.
//  The password used to create this JWT was "secret".
nSigVerified := oJwt:VerifyJwt(cToken, "secret")
? "with correct password: " + Str(nSigVerified)

//  Now try with a different password:
nSigVerified := oJwt:VerifyJwt(cToken, "secret2")
? "with incorrect password " + Str(nSigVerified)

//  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.
nLeeway := 60
nBTimeValid := oJwt:IsTimeValid(cToken, nLeeway)
? "time constraints valid: " + Str(nBTimeValid)

//  Now let's recover the original claims JSON (the payload).
cPayload := oJwt:GetPayload(cToken)
//  The payload will likely be in compact form:
? cPayload

//  We can format for human viewing by loading it into Chilkat's JSON object
//  and emit.
oJson := CreateObject("Chilkat.JsonObject")
nSuccess := oJson:Load(cPayload)
oJson:EmitCompact := 0
? oJson:Emit()

//  We can recover the original JOSE header in the same way:
cJoseHeader := oJwt:GetHeader(cToken)
//  The payload will likely be in compact form:
? cJoseHeader

//  We can format for human viewing by loading it into Chilkat's JSON object
//  and emit.
nSuccess := oJson:Load(cJoseHeader)
oJson:EmitCompact := 0
? oJson:Emit()

oJwt:destroy()
oJson:destroy()