Lua

Verify JWT Using an RSA Public Key (RS256, RS384, RS512)

Demonstrates how to verify a JWT that was signed using an RSA private key.

This example verifies the RSA 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 Lua Downloads

Lua

local chilkat = require("chilkat")

-- Demonstrates how to verify an JWT using an RSA public key.

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

local pubKey = chilkat.PublicKey.new()
local success = pubKey:load_from_file("qa_data/pem/rsa_public.pem")

local jwt = chilkat.Jwt.new()

local token = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDQ1MjM4LCJuYmYiOjE0NjM0NDUyMzgsImV4cCI6MTQ2MzQ0ODgzOH0.XRtqed6nuJ9lrp0wbNdDX3fCkSh_d9cHAniPbNcqm7G-5N3mtI5ntQvZBDP3pHtECVqufuDwW7XgUtzAi0ZXhyiRm1iZ3wMSN5lHWv52OQJmMHPA7VPd8Q1hDG-tx-QswzJKd75OEUHP7wIXq2Mg_YVElfDvJI6TGjGyS1y-RLHlz-ldlGsEwIBkO0PtzIYTVov97x8p9KCsPNhS4lZUIqKOYoTZUV5LpuAWARl-636DfMEB_A5_IEaw_W8leh2suP2ULVZxwE-Tk1kBC9tsSGrBrPTtg7sziaV4Lbb0JRANmh98uTRu5f8ji9CVOnpbMiAzjsJSy56kz_olweXSuA"

-- First verify the signature.
local sigVerified = jwt:verify_jwt_pk(token, pubKey)
print("verified: " .. 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()
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())