EllipticCurveSigner.java

/*
 * Copyright (C) 2015 jsonwebtoken.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.jsonwebtoken.impl.crypto;

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.PrivateKey;
import java.security.Signature;
import java.security.interfaces.ECPrivateKey;

import io.jsonwebtoken.JwtException;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.SignatureException;

public class EllipticCurveSigner extends EllipticCurveProvider implements Signer {

    public EllipticCurveSigner(SignatureAlgorithm alg, Key key) {
        super(alg, key);
        if (!(key instanceof ECPrivateKey)) {
            String msg = "Elliptic Curve signatures must be computed using an ECPrivateKey.  The specified key of " +
                         "type " + key.getClass().getName() + " is not an ECPrivateKey.";
            throw new IllegalArgumentException(msg);
        }
    }

    @Override
    public byte[] sign(byte[] data) {
        try {
            return doSign(data);
        } catch (InvalidKeyException e) {
            throw new SignatureException("Invalid Elliptic Curve PrivateKey. " + e.getMessage(), e);
        } catch (java.security.SignatureException e) {
            throw new SignatureException("Unable to calculate signature using Elliptic Curve PrivateKey. " + e.getMessage(), e);
        } catch (JwtException e) {
            throw new SignatureException("Unable to convert signature to JOSE format. " + e.getMessage(), e);
        }
    }

    protected byte[] doSign(byte[] data) throws InvalidKeyException, java.security.SignatureException, JwtException {
        PrivateKey privateKey = (PrivateKey)key;
        Signature sig = createSignatureInstance();
        sig.initSign(privateKey);
        sig.update(data);
        return transcodeSignatureToConcat(sig.sign(), getSignatureByteArrayLength(alg));
    }
}