PowerBuilder

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.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Http
oleobject loo_SbPubKeys
string ls_Token
oleobject loo_Jwt
string ls_Header
oleobject loo_Json
string ls_Kid
oleobject loo_JsonPubKeys
oleobject loo_JsonKey
oleobject loo_PubKey

li_Success = 0

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

loo_Http = create oleobject
li_rc = loo_Http.ConnectToNewObject("Chilkat.Http")
if li_rc < 0 then
    destroy loo_Http
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_SbPubKeys = create oleobject
li_rc = loo_SbPubKeys.ConnectToNewObject("Chilkat.StringBuilder")

li_Success = loo_Http.QuickGetSb("https://www.googleapis.com/oauth2/v3/certs",loo_SbPubKeys)
if li_Success = 0 then
    Write-Debug loo_Http.LastErrorText
    destroy loo_Http
    destroy loo_SbPubKeys
    return
end if

Write-Debug loo_SbPubKeys.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.
// -------------------------------------------------------------------------------------------
ls_Token = "eyJhbGciOiJSUzI1NiIsImtpZCI6IjQyZmY5MGQ3ZDM0OGM5NzM4MWE3YzExOWVmMWY1MzI0ZWEzZjViZWIifQ.eyJpc3MiOiJodHRwczovL2FjY291bnRzLmdvb2dsZS5jb20iLCJzdWIiOiIxMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExMTExIiwiaWF0IjoxNjExMTE1MTQzLCJleHAiOjE2MTEyMDE1NDMsImF1ZCI6IjQyOTc1NzExNTE0ODg0OSJ9.pLem5i0bx3M7lJYj7jKv2Nq7c07X5YpZz-x1uM5RniW-v4LsX-lKIVvOq2x3-WoPqkzLXJfP0kG0dx1uD2q1NfFQK60YwKH4FnFtB6INnUP1dRVpP9_pTTKyAE28I3s5Tay4PbPdrCl7ZLCIJzCfpCW1TiWeVoPjp5HgZKTBHdP_sEkN_yO5dQerQXAkFJkV3kNgF9jI3ayT-KPqOIH6GVoWXjHFDyA2EYgJPEFRo5WSe6XycJ85p5duwT-OoBcb_kJZG9PxYd91eHlPCzp8vGxzIb2dVROCBxyM8e8W0cd9v15hfmpg9R-eG9vCM5y63ZLChZLFeHFx0Pd7hvAqfKg"

loo_Jwt = create oleobject
li_rc = loo_Jwt.ConnectToNewObject("Chilkat.Jwt")

ls_Header = loo_Jwt.GetHeader(ls_Token)

Write-Debug ls_Header

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

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

loo_Json = create oleobject
li_rc = loo_Json.ConnectToNewObject("Chilkat.JsonObject")

loo_Json.Load(ls_Header)
ls_Kid = loo_Json.StringOf("kid")

Write-Debug "kid = " + ls_Kid

loo_JsonPubKeys = create oleobject
li_rc = loo_JsonPubKeys.ConnectToNewObject("Chilkat.JsonObject")

loo_JsonPubKeys.LoadSb(loo_SbPubKeys)

loo_JsonKey = loo_JsonPubKeys.FindRecord("keys","kid",ls_Kid,1)
if loo_JsonPubKeys.LastMethodSuccess = 0 then
    Write-Debug "Did not find a matching public key based on the kid."
    destroy loo_Http
    destroy loo_SbPubKeys
    destroy loo_Jwt
    destroy loo_Json
    destroy loo_JsonPubKeys
    return
end if

Write-Debug loo_JsonKey.Emit()

// Load the matching public key into a Chilkat public key object.
loo_PubKey = create oleobject
li_rc = loo_PubKey.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey.LoadFromString(loo_JsonKey.Emit())
destroy loo_JsonKey
if li_Success = 0 then
    Write-Debug loo_PubKey.LastErrorText
    destroy loo_Http
    destroy loo_SbPubKeys
    destroy loo_Jwt
    destroy loo_Json
    destroy loo_JsonPubKeys
    destroy loo_PubKey
    return
end if

// ----------------------------------------------------------------------------------------
// 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


destroy loo_Http
destroy loo_SbPubKeys
destroy loo_Jwt
destroy loo_Json
destroy loo_JsonPubKeys
destroy loo_PubKey