PowerShell Requires Chilkat v11.0.0+

Verify a JWT Created by the Amazon Cognito Service

See more JSON Web Token (JWT) Examples

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

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  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:

$http = New-Object Chilkat.Http
$sbJsonKeys = New-Object Chilkat.StringBuilder
$success = $http.QuickGetSb("https://cognito-idp.us-east-2.amazonaws.com/us-east-2_******/.well-known/jwks.json",$sbJsonKeys)
if ($success -eq $false) {
    $($http.LastErrorText)
    exit
}

$jsonKeys = New-Object Chilkat.JsonObject
$jsonKeys.LoadSb($sbJsonKeys)
$jsonKeys.EmitCompact = $false
$($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.
$jsonKey1 = New-Object Chilkat.JsonObject
$jsonKeys.ObjectOf2("keys[0]",$jsonKey1)

$pubKey1 = New-Object Chilkat.PublicKey
$success = $pubKey1.LoadFromString($jsonKey1.Emit())
if ($success -eq $false) {
    $($pubKey1.LastErrorText)
    exit
}

$("Success")

$jwt = New-Object Chilkat.Jwt

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

#  First verify the signature.
$sigVerified = $jwt.VerifyJwtPk($token,$pubKey1)
$("verified: " + $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.
$leeway = 60
$bTimeValid = $jwt.IsTimeValid($token,$leeway)
$("time constraints valid: " + $bTimeValid)

#  Now let's recover the original claims JSON (the payload).
$payload = $jwt.GetPayload($token)
#  The payload will likely be in compact form:
$($payload)

#  We can format for human viewing by loading it into Chilkat's JSON object
#  and emit.
$json = New-Object Chilkat.JsonObject
$success = $json.Load($payload)
$json.EmitCompact = $false
$($json.Emit())

#  We can recover the original JOSE header in the same way:
$joseHeader = $jwt.GetHeader($token)
#  The payload will likely be in compact form:
$($joseHeader)

#  We can format for human viewing by loading it into Chilkat's JSON object
#  and emit.
$success = $json.Load($joseHeader)
$json.EmitCompact = $false
$($json.Emit())