Visual FoxPro

Verify a Google JWT Using Google's Public Key

See more Google APIs Examples

Demonstrates how to verify a JWT that was signed using Google's 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.

Visual FoxPro

LOCAL lnSuccess
LOCAL loHttp
LOCAL loSbPubKeys
LOCAL lcToken
LOCAL loJwt
LOCAL lcHeader
LOCAL loJson
LOCAL lcKid
LOCAL loJsonPubKeys
LOCAL loJsonKey
LOCAL loPubKey

lnSuccess = 0

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

loHttp = CreateObject('Chilkat.Http')
loSbPubKeys = CreateObject('Chilkat.StringBuilder')

lnSuccess = loHttp.QuickGetSb("https://www.googleapis.com/oauth2/v3/certs",loSbPubKeys)
IF (lnSuccess = 0) THEN
    ? loHttp.LastErrorText
    RELEASE loHttp
    RELEASE loSbPubKeys
    CANCEL
ENDIF

? loSbPubKeys.GetAsString()

* Here are the keys:

* {
*   "keys": [
*     {
*       "e": "AQAB",
*       "n": "4bAT6C6EeX8Dspje3FrAXw-nnhNk04e1RmNa4kjc0CHf6Pk7ryARlwA-6YilyPABqQfYHx60s8oSnxvUVprFfQ2-Q8aAZO7bPKSxnoGlcKERL2oLNA4Msvc89N9Y5ycThZUplf_QC19e6jyYXN6Nz-UnJSCLrtQY8tVhhVRs61j4A2N_p-enAi-r704Qi1-v-DKV4eVRkClKViploo8NyjUaT9L4vbBssPCjyimJzsWnEe1fED5c4LnHeArYzA_FEn3JJotqDIz9t2VnvZNTMhizHEX4VnORlEWMEfR8n4CEHQx7PcQUOmfqyw08gWeXQl1-uTjtIGaE-sRIv9u_vQ",
*       "kty": "RSA",
*       "use": "sig",
*       "alg": "RS256",
*       "kid": "2af90e87be140c20038898a6efa11283dab6031d"
*     },
*     {
*       "n": "nzGsrziOYrMVYMpvUZOwkKNiPWcOPTYRYlDSdRW4UpAHdWPbPlyqaaphYhoMB5DXrVxI3bdvm7DOlo-sHNnulmAFQa-7TsQMxrZCvVdAbyXGID9DZYEqf8mkCV1Ohv7WY5lDUqlybIk1OSHdK7-1et0QS8nn-5LojGg8FK4ssLf3mV1APpujl27D1bDhyRb1MGumXYElwlUms7F9p9OcSp5pTevXCLmXs9MJJk4o9E1zzPpQ9Ko0lH9l_UqFpA7vwQhnw0nbh73rXOX2TUDCUqL4ThKU5Z9Pd-eZCEOatKe0mJTpQ00XGACBME_6ojCdfNIJr84Y_IpGKvkAEksn9w",
*       "use": "sig",
*       "kid": "87bbe0815b064e6d449cac999f0e50e72a3e4374",
*       "e": "AQAB",
*       "alg": "RS256",
*       "kty": "RSA"
*     }
*   ]
* }

* -------------------------------------------------------------------------------------------
* Replace this with your actual token.
* This sample token contains a kid that does not match any of the above Google public keys.
* -------------------------------------------------------------------------------------------
lcToken = "eyJhbGciOiJSUzI1NiIsImtpZCI6IjQyZmY5MGQ3ZDM0OGM5NzM4MWE3YzExOWVmMWY1MzI0ZWEzZjViZWIifQ.eyJpc3MiOiJodHRwczovL2FjY291bnRzLmdvb2dsZS5jb20iLCJzdWIiOiIxMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExIiwiaWF0IjoxNjExMTE1MTQzLCJleHAiOjE2MTEyMDE1NDMsImF1ZCI6IjQyOTc1NzExNTE0ODg0OSJ9.pLem5i0bx3M7lJYj7jKv2Nq7c07X5YpZz-x1uM5RniW-v4LsX-lKIVvOq2x3-WoPqkzLXJfP0kG0dx1uD2q1NfFQK60YwKH4FnFtB6INnUP1dRVpP9_pTTKyAE28I3s5Tay4PbPdrCl7ZLCIJzCfpCW1TiWeVoPjp5HgZKTBHdP_sEkN_yO5dQerQXAkFJkV3kNgF9jI3ayT-KPqOIH6GVoWXjHFDyA2EYgJPEFRo5WSe6XycJ85p5duwT-OoBcb_kJZG9PxYd91eHlPCzp8vGxzIb2dVROCBxyM8e8W0cd9v15hfmpg9R-eG9vCM5y63ZLChZLFeHFx0Pd7hvAqfKg"

loJwt = CreateObject('Chilkat.Jwt')
lcHeader = loJwt.GetHeader(lcToken)

? lcHeader

* Sample header:
* {"alg":"RS256","kid":"87bbe0815b064e6d449cac999f0e50e72a3e4374"}

* Load the public key matching the "kid" into a Chilkat public key object, then verify..

loJson = CreateObject('Chilkat.JsonObject')
loJson.Load(lcHeader)
lcKid = loJson.StringOf("kid")

? "kid = " + lcKid

loJsonPubKeys = CreateObject('Chilkat.JsonObject')
loJsonPubKeys.LoadSb(loSbPubKeys)

loJsonKey = loJsonPubKeys.FindRecord("keys","kid",lcKid,1)
IF (loJsonPubKeys.LastMethodSuccess = 0) THEN
    ? "Did not find a matching public key based on the kid."
    RELEASE loHttp
    RELEASE loSbPubKeys
    RELEASE loJwt
    RELEASE loJson
    RELEASE loJsonPubKeys
    CANCEL
ENDIF

? loJsonKey.Emit()

* Load the matching public key into a Chilkat public key object.
loPubKey = CreateObject('Chilkat.PublicKey')
lnSuccess = loPubKey.LoadFromString(loJsonKey.Emit())
RELEASE loJsonKey
IF (lnSuccess = 0) THEN
    ? loPubKey.LastErrorText
    RELEASE loHttp
    RELEASE loSbPubKeys
    RELEASE loJwt
    RELEASE loJson
    RELEASE loJsonPubKeys
    RELEASE loPubKey
    CANCEL
ENDIF

* ----------------------------------------------------------------------------------------
* Now we can validate the JWT using Google's public key as shown in this example:
* (Except we use the public key obtained as shown above instead of a public key loaded from a PEM file.
* 
* See Verify JWT Using an RSA Public Key

RELEASE loHttp
RELEASE loSbPubKeys
RELEASE loJwt
RELEASE loJson
RELEASE loJsonPubKeys
RELEASE loPubKey