Java Requires Chilkat v11.0.0+

Validate a JWS Using ECDSA P-256 SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256 Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.Jws;
import com.chilkatsoft.chilkat2.PublicKey;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

    public static void main(String[] args) {
        // This requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        // This example takes a JSON signature in compact serialization format,
        // and uses an ECDSA public key to validate and recover the protected header and payload.

        // We only need a public key for signature validation.  This is the ECDSA public key
        // that is used:

        //      {"kty":"EC",
        //       "crv":"P-256",
        //       "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",
        //       "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"
        //      }

        StringBuilder sbPubKey = new StringBuilder();
        sbPubKey.append("{\"kty\":\"EC\",");
        sbPubKey.append("\"crv\":\"P-256\",");
        sbPubKey.append("\"x\":\"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\",");
        sbPubKey.append("\"y\":\"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\"");
        sbPubKey.append("}");

        PublicKey pubKey = new PublicKey();
        try {
            pubKey.loadFromString(sbPubKey.getAsString());
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        Jws jws = new Jws();

        // Set the ECC public key:
        int signatureIndex = 0;
        jws.setPublicKey(signatureIndex, pubKey);

        // Load the JWS.
        StringBuilder sbJws = new StringBuilder();
        sbJws.append("eyJhbGciOiJFUzI1NiJ9");
        sbJws.append(".");
        sbJws.append("eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt");
        sbJws.append("cGxlLmNvbS9pc19yb290Ijp0cnVlfQ");
        sbJws.append(".");
        sbJws.append("DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA");
        sbJws.append("pmWQxfKTUJqPP3-Kg6NU1Q");

        try {
            jws.loadJwsSb(sbJws);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Validate the 1st (and only) signature at index 0..
        int v = jws.validate(signatureIndex);
        if (v < 0) {
            // Perhaps Chilkat was not unlocked or the trial expired..
            System.out.println("Method call failed for some other reason.");
            System.out.println(jws.getLastErrorText());
            return;
        }

        if (v == 0) {
            System.out.println("Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both.");
            return;
        }

        // If we get here, the signature was validated..
        System.out.println("Signature validated.");
        System.out.println("--");

        // Recover the original content:
        System.out.println("Recovered content:");
        System.out.println(jws.getPayload("utf-8"));
        System.out.println("--");

        // Examine the protected header:

        JsonObject joseHeader = new JsonObject();
        try {
            jws.getProtectedH(signatureIndex, joseHeader);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        joseHeader.setEmitCompact(false);

        System.out.println("Protected (JOSE) header:");
        System.out.println(joseHeader.emit());

        // Output:

        //     Signature validated.
        //     --
        //     Recovered content:
        //     {"iss":"joe",
        //      "exp":1300819380,
        //      "http://example.com/is_root":true}
        //     --
        //     Protected (JOSE) header:
        //     {
        //       "alg": "ES256"
        //     }
    }
}