(C# UWP/WinRT) Verify JWT with EdDSA / Ed25519 Signature

Note: This example requires Chilkat v9.5.0.84 or greater.

Demonstrates how to verify a JWT that was signed using an Ed25519 private key.

This example verifies the EdDSA 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 data.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

// Demonstrates how to verify a JWT with an EdDSA/Ed25519 Signature
// *** Requires Chilkat v9.5.0.84 or greater.

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

// Use this Ed25519 public key for verification

string jsonPubKey = "{\"kty\": \"OKP\",\"alg\": \"EdDSA\",\"crv\": \"Ed25519\",\"x\": \"11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo\"}";

Chilkat.PublicKey pubKey = new Chilkat.PublicKey();
bool success = pubKey.LoadFromString(jsonPubKey);
if (success == false) {
    Debug.WriteLine(pubKey.LastErrorText);
    return;
}

Chilkat.Jwt jwt = new Chilkat.Jwt();
string token = "eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg";

// First verify the signature.
bool sigVerified = jwt.VerifyJwtPk(token,pubKey);
Debug.WriteLine("verified: " + Convert.ToString(sigVerified));

if (sigVerified == false) {
    Debug.WriteLine(jwt.LastErrorText);
    return;
}

// 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));

// Recover the original data (the payload).
string payload = jwt.GetPayload(token);
Debug.WriteLine(payload);

// Recover the original JOSE header in the same way:
string joseHeader = jwt.GetHeader(token);
Debug.WriteLine(joseHeader);