Main.java Source code

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Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * 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.
 */

import java.security.Key;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.KeyFactory;

import java.security.Signature;

import java.security.spec.ECPublicKeySpec;
import java.security.spec.ECPrivateKeySpec;

import java.security.spec.InvalidKeySpecException;

public class Main {
    static byte[] sign(PrivateKey privateKey, byte[] input) throws Exception {
        Signature signer = Signature.getInstance(getSignatureAlgorithm(privateKey));
        signer.initSign(privateKey);
        signer.update(input);
        return signer.sign();
    }

    private static String getSignatureAlgorithm(Key key) throws Exception {
        if ("EC".equals(key.getAlgorithm())) {
            int curveSize;
            KeyFactory factory = KeyFactory.getInstance("EC");

            if (key instanceof PublicKey) {
                ECPublicKeySpec spec = factory.getKeySpec(key, ECPublicKeySpec.class);
                curveSize = spec.getParams().getCurve().getField().getFieldSize();
            } else if (key instanceof PrivateKey) {
                ECPrivateKeySpec spec = factory.getKeySpec(key, ECPrivateKeySpec.class);
                curveSize = spec.getParams().getCurve().getField().getFieldSize();
            } else {
                throw new InvalidKeySpecException();
            }

            if (curveSize <= 256) {
                return "SHA256withECDSA";
            } else if (curveSize <= 384) {
                return "SHA384withECDSA";
            } else {
                return "SHA512withECDSA";
            }
        } else if ("RSA".equals(key.getAlgorithm())) {
            return "SHA256withRSA";
        } else {
            throw new IllegalArgumentException("Unsupported key type " + key.getAlgorithm());
        }
    }
}