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++

#include <CkHttp.h>
#include <CkStringBuilder.h>
#include <CkJsonObject.h>
#include <CkPublicKey.h>
#include <CkJwt.h>

void ChilkatSample(void)
    {
    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:

    CkHttp http;
    CkStringBuilder sbJsonKeys;
    success = http.QuickGetSb("https://cognito-idp.us-east-2.amazonaws.com/us-east-2_******/.well-known/jwks.json",sbJsonKeys);
    if (success == false) {
        std::cout << http.lastErrorText() << "\r\n";
        return;
    }

    CkJsonObject jsonKeys;
    jsonKeys.LoadSb(sbJsonKeys);
    jsonKeys.put_EmitCompact(false);
    std::cout << jsonKeys.emit() << "\r\n";

    //  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.
    CkJsonObject jsonKey1;
    jsonKeys.ObjectOf2("keys[0]",jsonKey1);

    CkPublicKey pubKey1;
    success = pubKey1.LoadFromString(jsonKey1.emit());
    if (success == false) {
        std::cout << pubKey1.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "Success" << "\r\n";

    CkJwt jwt;

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

    //  First verify the signature.
    bool sigVerified = jwt.VerifyJwtPk(token,pubKey1);
    std::cout << "verified: " << sigVerified << "\r\n";

    //  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);
    std::cout << "time constraints valid: " << bTimeValid << "\r\n";

    //  Now let's recover the original claims JSON (the payload).
    const char *payload = jwt.getPayload(token);
    //  The payload will likely be in compact form:
    std::cout << payload << "\r\n";

    //  We can format for human viewing by loading it into Chilkat's JSON object
    //  and emit.
    CkJsonObject json;
    success = json.Load(payload);
    json.put_EmitCompact(false);
    std::cout << json.emit() << "\r\n";

    //  We can recover the original JOSE header in the same way:
    const char *joseHeader = jwt.getHeader(token);
    //  The payload will likely be in compact form:
    std::cout << joseHeader << "\r\n";

    //  We can format for human viewing by loading it into Chilkat's JSON object
    //  and emit.
    success = json.Load(joseHeader);
    json.put_EmitCompact(false);
    std::cout << json.emit() << "\r\n";
    }