Java ECC算法加密

ECC-Elliptic Curves Cryptography，椭圆曲线密码编码学，是目前已知的公钥体制中，对每比特所提供加密强度最高的一种体制。在软件注册保护方面起到很大的作用，一般的序列号通常由该算法产生。

关于Java实现ECC算法的资料实在是太少了，无论是国内还是国外的资料，无论是官方还是非官方的解释，最终只有一种答案——ECC算法在jdk1.5后加入支持，目前仅仅只能完成密钥的生成与解析。

尽管如此，我照旧提供相应的Java实现代码，以供大家参考。

通过java代码实现如下：
import java.math.BigInteger;
import java.security.Key;
import java.security.KeyFactory;
import java.security.interfaces.ECPrivateKey;
import java.security.interfaces.ECPublicKey;
import java.security.spec.ECFieldF2m;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPrivateKeySpec;
import java.security.spec.ECPublicKeySpec;
import java.security.spec.EllipticCurve;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;
import javax.crypto.NullCipher;

import sun.security.ec.ECKeyFactory;
import sun.security.ec.ECPrivateKeyImpl;
import sun.security.ec.ECPublicKeyImpl;

public abstract class ECCCoder extends Coder {

public static final String ALGORITHM = "EC";
private static final String PUBLIC_KEY = "ECCPublicKey";
private static final String PRIVATE_KEY = "ECCPrivateKey";

/**
* 解密

* 用私钥解密
*
* @param data
* @param key
* @return
* @throws Exception
*/
public static byte[] decrypt(byte[] data, String key) throws Exception {
// 对密钥解密
byte[] keyBytes = decryptBASE64(key);

// 取得私钥
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = ECKeyFactory.INSTANCE;

ECPrivateKey priKey = (ECPrivateKey) keyFactory
.generatePrivate(pkcs8KeySpec);

ECPrivateKeySpec ecPrivateKeySpec = new ECPrivateKeySpec(priKey.getS(),
priKey.getParams());

// 对数据解密
// TODO Chipher不支持EC算法 未能实现
Cipher cipher = new NullCipher();
// Cipher.getInstance(ALGORITHM, keyFactory.getProvider());
cipher.init(Cipher.DECRYPT_MODE, priKey, ecPrivateKeySpec.getParams());

return cipher.doFinal(data);
}

/**
* 加密

* 用公钥加密
*
* @param data
* @param privateKey
* @return
* @throws Exception
*/
public static byte[] encrypt(byte[] data, String privateKey)
throws Exception {
// 对公钥解密
byte[] keyBytes = decryptBASE64(privateKey);

// 取得公钥
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = ECKeyFactory.INSTANCE;

ECPublicKey pubKey = (ECPublicKey) keyFactory
.generatePublic(x509KeySpec);

ECPublicKeySpec ecPublicKeySpec = new ECPublicKeySpec(pubKey.getW(),
pubKey.getParams());

// 对数据加密
// TODO Chipher不支持EC算法 未能实现
Cipher cipher = new NullCipher();
// Cipher.getInstance(ALGORITHM, keyFactory.getProvider());
cipher.init(Cipher.ENCRYPT_MODE, pubKey, ecPublicKeySpec.getParams());

return cipher.doFinal(data);
}

/**
* 取得私钥
*
* @param keyMap
* @return
* @throws Exception
*/
public static String getPrivateKey(Map keyMap)
throws Exception {
Key key = (Key) keyMap.get(PRIVATE_KEY);

return encryptBASE64(key.getEncoded());
}

/**
* 取得公钥
*
* @param keyMap
* @return
* @throws Exception
*/
public static String getPublicKey(Map keyMap)
throws Exception {
Key key = (Key) keyMap.get(PUBLIC_KEY);

return encryptBASE64(key.getEncoded());
}

/**
* 初始化密钥
*
* @return
* @throws Exception
*/
public static Map initKey() throws Exception {
BigInteger x1 = new BigInteger(
"2fe13c0537bbc11acaa07d793de4e6d5e5c94eee8", 16);
BigInteger x2 = new BigInteger(
"289070fb05d38ff58321f2e800536d538ccdaa3d9", 16);

ECPoint g = new ECPoint(x1, x2);

// the order of generator
BigInteger n = new BigInteger(
"5846006549323611672814741753598448348329118574063", 10);
// the cofactor
int h = 2;
int m = 163;
int[] ks = { 7, 6, 3 };
ECFieldF2m ecField = new ECFieldF2m(m, ks);
// y^2+xy=x^3+x^2+1
BigInteger a = new BigInteger("1", 2);
BigInteger b = new BigInteger("1", 2);

EllipticCurve ellipticCurve = new EllipticCurve(ecField, a, b);

ECParameterSpec ecParameterSpec = new ECParameterSpec(ellipticCurve, g,
n, h);
// 公钥
ECPublicKey publicKey = new ECPublicKeyImpl(g, ecParameterSpec);

BigInteger s = new BigInteger(
"1234006549323611672814741753598448348329118574063", 10);
// 私钥
ECPrivateKey privateKey = new ECPrivateKeyImpl(s, ecParameterSpec);

Map keyMap = new HashMap(2);

keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);

return keyMap;
}

}


请注意上述代码中的TODO内容，再次提醒注意，Chipher不支持EC算法 ，以上代码仅供参考。Chipher、Signature、KeyPairGenerator、KeyAgreement、SecretKey均不支持EC算法。为了确保程序能够正常执行，我们使用了NullCipher类，验证程序。

照旧提供一个测试类：
import static org.junit.Assert.*;

import java.math.BigInteger;
import java.security.spec.ECFieldF2m;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPrivateKeySpec;
import java.security.spec.ECPublicKeySpec;
import java.security.spec.EllipticCurve;
import java.util.Map;

import org.junit.Test;

public class ECCCoderTest {

@Test
public void test() throws Exception {
String inputStr = "abc";
byte[] data = inputStr.getBytes();

Map keyMap = ECCCoder.initKey();

String publicKey = ECCCoder.getPublicKey(keyMap);
String privateKey = ECCCoder.getPrivateKey(keyMap);
System.err.println("公钥: \n" + publicKey);
System.err.println("私钥： \n" + privateKey);

byte[] encodedData = ECCCoder.encrypt(data, publicKey);

byte[] decodedData = ECCCoder.decrypt(encodedData, privateKey);

String outputStr = new String(decodedData);
System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
assertEquals(inputStr, outputStr);
}
}

控制台输出：
公钥:
MEAwEAYHKoZIzj0CAQYFK4EEAAEDLAAEAv4TwFN7vBGsqgfXk95ObV5clO7oAokHD7BdOP9YMh8u
gAU21TjM2qPZ

私钥：
MDICAQAwEAYHKoZIzj0CAQYFK4EEAAEEGzAZAgEBBBTYJsR3BN7TFw7JHcAHFkwNmfil7w==

加密前: abc

解密后: abc