Java

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 Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    //  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" 
    //       } 

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

    CkPublicKey pubKey = new CkPublicKey();
    success = pubKey.LoadFromString(sbPubKey.getAsString());
    if (success == false) {
        System.out.println(pubKey.lastErrorText());
        return;
        }

    CkJws jws = new CkJws();

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

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

    success = jws.LoadJwsSb(sbJws);
    if (success == false) {
        System.out.println(jws.lastErrorText());
        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.lastErrorText());
        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:

    CkJsonObject joseHeader = new CkJsonObject();
    success = jws.GetProtectedH(signatureIndex,joseHeader);
    if (success == false) {
        System.out.println(jws.lastErrorText());
        return;
        }

    joseHeader.put_EmitCompact(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"
    //  	}
  }
}