Lua

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.

Lua

local chilkat = require("chilkat")

-- 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.

local jwt = chilkat.Jwt.new()

local token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

-- First verify the signature.
-- The password used to create this JWT was "secret".
local sigVerified = jwt:verify_jwt(token, "secret")
print("with correct password: " .. tostring(sigVerified))

-- Now try with a different password:
sigVerified = jwt:verify_jwt(token, "secret2")
print("with incorrect password " .. tostring(sigVerified))

-- 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 leeway = 60
local bTimeValid = jwt:is_time_valid(token, leeway)
print("time constraints valid: " .. tostring(bTimeValid))

-- Now let's recover the original claims JSON (the payload).
local payload = jwt:get_payload(token)
-- The payload will likely be in compact form:
print(payload)

-- We can format for human viewing by loading it into Chilkat's JSON object
-- and emit.
local json = chilkat.JsonObject.new()
local success = json:load(payload)
json.emit_compact = false
print(json:emit())

-- We can recover the original JOSE header in the same way:
local joseHeader = jwt:get_header(token)
-- The payload will likely be in compact form:
print(joseHeader)

-- We can format for human viewing by loading it into Chilkat's JSON object
-- and emit.
success = json:load(joseHeader)
json.emit_compact = false
print(json:emit())