C#

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. C#

bool 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:

Chilkat.Http http = new Chilkat.Http();
Chilkat.StringBuilder sbJsonKeys = new Chilkat.StringBuilder();
success = http.QuickGetSb("https://cognito-idp.us-east-2.amazonaws.com/us-east-2_******/.well-known/jwks.json",sbJsonKeys);
if (success == false) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

Chilkat.JsonObject jsonKeys = new Chilkat.JsonObject();
jsonKeys.LoadSb(sbJsonKeys);
jsonKeys.EmitCompact = false;
Debug.WriteLine(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.
Chilkat.JsonObject jsonKey1 = new Chilkat.JsonObject();
jsonKeys.ObjectOf2("keys[0]",jsonKey1);

Chilkat.PublicKey pubKey1 = new Chilkat.PublicKey();
success = pubKey1.LoadFromString(jsonKey1.Emit());
if (success == false) {
    Debug.WriteLine(pubKey1.LastErrorText);
    return;
}

Debug.WriteLine("Success");

Chilkat.Jwt jwt = new Chilkat.Jwt();

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

//  First verify the signature.
bool sigVerified = jwt.VerifyJwtPk(token,pubKey1);
Debug.WriteLine("verified: " + Convert.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.
int leeway = 60;
bool bTimeValid = jwt.IsTimeValid(token,leeway);
Debug.WriteLine("time constraints valid: " + Convert.ToString(bTimeValid));

//  Now let's recover the original claims JSON (the payload).
string payload = jwt.GetPayload(token);
//  The payload will likely be in compact form:
Debug.WriteLine(payload);

//  We can format for human viewing by loading it into Chilkat's JSON object
//  and emit.
Chilkat.JsonObject json = new Chilkat.JsonObject();
success = json.Load(payload);
json.EmitCompact = false;
Debug.WriteLine(json.Emit());

//  We can recover the original JOSE header in the same way:
string joseHeader = jwt.GetHeader(token);
//  The payload will likely be in compact form:
Debug.WriteLine(joseHeader);

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