(PowerBuilder) Verify a JWT Created by the Amazon Cognito Service

Demonstrates how to verify a JWT created by the Amazon Cognito Service.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

integer li_rc
oleobject loo_Http
oleobject loo_SbJsonKeys
integer li_Success
oleobject loo_JsonKeys
oleobject loo_JsonKey1
oleobject loo_PubKey1
oleobject loo_Jwt
string ls_Token
integer li_SigVerified
integer li_Leeway
integer li_BTimeValid
string ls_Payload
oleobject loo_Json
string ls_JoseHeader

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

// The public keys for this example are at https://cognito-idp.us-east-2.amazonaws.com/us-east-2_******/.well-known/jwks.json
// Let's get them:

loo_Http = create oleobject
// Use "Chilkat_9_5_0.Http" for versions of Chilkat < 10.0.0
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_SbJsonKeys = create oleobject
// Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
li_rc = loo_SbJsonKeys.ConnectToNewObject("Chilkat.StringBuilder")

li_Success = loo_Http.QuickGetSb("https://cognito-idp.us-east-2.amazonaws.com/us-east-2_******/.well-known/jwks.json",loo_SbJsonKeys)
if li_Success = 0 then
    Write-Debug loo_Http.LastErrorText
    destroy loo_Http
    destroy loo_SbJsonKeys
    return
end if

loo_JsonKeys = create oleobject
// Use "Chilkat_9_5_0.JsonObject" for versions of Chilkat < 10.0.0
li_rc = loo_JsonKeys.ConnectToNewObject("Chilkat.JsonObject")

loo_JsonKeys.LoadSb(loo_SbJsonKeys)
loo_JsonKeys.EmitCompact = 0
Write-Debug loo_JsonKeys.Emit()

// Here are the keys:

// {
//   "keys": [
//     {
//       "alg": "RS256",
//       "e": "AQAB",
//       "kid": "1A/L5Fsb2EsEwxy5E0cmCMS1BnMe6Jl6NXiMig4iNwU=",
//       "kty": "RSA",
//       "n": "y0w7BJrIJYi ... jKG27z2P3OKw",
//       "use": "sig"
//     },
//     {
//       "alg": "RS256",
//       "e": "AQAB",
//       "kid": "mos6VTJnvDwurY3ghJg6IAPUq+dMwl6CL/iThzJOkzg=",
//       "kty": "RSA",
//       "n": "qbIEH-7tg6yrT ... 3Fj94ooTd0w",
//       "use": "sig"
//     }
//   ]
// }

// Try the 1st key.
loo_JsonKey1 = loo_JsonKeys.ObjectOf("keys[0]")
if loo_JsonKeys.LastMethodSuccess = 0 then
    Write-Debug "Did not get the 1st JSON public key."
    destroy loo_Http
    destroy loo_SbJsonKeys
    destroy loo_JsonKeys
    return
end if

loo_PubKey1 = create oleobject
// Use "Chilkat_9_5_0.PublicKey" for versions of Chilkat < 10.0.0
li_rc = loo_PubKey1.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey1.LoadFromString(loo_JsonKey1.Emit())
if li_Success = 0 then
    Write-Debug loo_PubKey1.LastErrorText
    destroy loo_Http
    destroy loo_SbJsonKeys
    destroy loo_JsonKeys
    destroy loo_PubKey1
    return
end if

destroy loo_JsonKey1

Write-Debug "Success"

loo_Jwt = create oleobject
// Use "Chilkat_9_5_0.Jwt" for versions of Chilkat < 10.0.0
li_rc = loo_Jwt.ConnectToNewObject("Chilkat.Jwt")

// I did not include the an actual AWS Cognito token here because our test sample used customer-provided data..
ls_Token = "eyJ..asXg"

// First verify the signature.
li_SigVerified = loo_Jwt.VerifyJwtPk(ls_Token,loo_PubKey1)
Write-Debug "verified: " + string(li_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.
li_Leeway = 60
li_BTimeValid = loo_Jwt.IsTimeValid(ls_Token,li_Leeway)
Write-Debug "time constraints valid: " + string(li_BTimeValid)

// Now let's recover the original claims JSON (the payload).
ls_Payload = loo_Jwt.GetPayload(ls_Token)
// The payload will likely be in compact form:
Write-Debug ls_Payload

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
loo_Json = create oleobject
// Use "Chilkat_9_5_0.JsonObject" for versions of Chilkat < 10.0.0
li_rc = loo_Json.ConnectToNewObject("Chilkat.JsonObject")

li_Success = loo_Json.Load(ls_Payload)
loo_Json.EmitCompact = 0
Write-Debug loo_Json.Emit()

// We can recover the original JOSE header in the same way:
ls_JoseHeader = loo_Jwt.GetHeader(ls_Token)
// The payload will likely be in compact form:
Write-Debug ls_JoseHeader

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
li_Success = loo_Json.Load(ls_JoseHeader)
loo_Json.EmitCompact = 0
Write-Debug loo_Json.Emit()


destroy loo_Http
destroy loo_SbJsonKeys
destroy loo_JsonKeys
destroy loo_PubKey1
destroy loo_Jwt
destroy loo_Json