ECC
ECC-Elliptic Curves Cryptography，橢圓曲線密碼編碼學，是目前已知的公鑰體制中，對每比特所提供加密強度最高的一種體制。在軟件注冊保護方面起到很大的作用，一般的序列號通常由該算法產生。
當我開始整理《Java加密技術（二）》的時候，我就已經在開始研究ECC了，但是關於Java實現ECC算法的資料實在是太少了，無論是國內還是國外的資料，無論是官方還是非官方的解釋，最終只有一種答案——ECC算法在jdk1.5後加入支持，目前僅僅只能完成密鑰的生成與解析。
盡管如此，我照舊提供相應的Java實現代碼，以供大家參考。
通過java代碼實現如下：Coder類見 Java加密技術（一）
Java代碼
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;
/**
* ECC安全編碼組件
*
* @author 梁棟
* @version 1.0
* @since 1.0
*/
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<br>
* 用私鑰解密
*
* @param data
* @param key
* @return
* @throws Exception
*/
public static byte[] decrypt(byte[] data, String key) throws Exception {
// 對密鑰解密
byte[] keyBytes = decryptBASE64(key);
// 取得私鑰
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = ECKeyFactory.INSTANCE;
ECPrivateKey priKey = (ECPrivateKey) keyFactory
.generatePrivate(pkcs8KeySpec);
ECPrivateKeySpec ecPrivateKeySpec = new ECPrivateKeySpec(priKey.getS(),
priKey.getParams());
// 對數據解密
// TODO Chipher不支持EC算法 未能實現
Cipher cipher = new NullCipher();
// Cipher.getInstance(ALGORITHM, keyFactory.getProvider());
cipher.init(Cipher.DECRYPT_MODE, priKey, ecPrivateKeySpec.getParams());
return cipher.doFinal(data);
}
/**
* 加密<br>
* 用公鑰加密
*
* @param data
* @param privateKey
* @return
* @throws Exception
*/
public static byte[] encrypt(byte[] data, String privateKey)
throws Exception {
// 對公鑰解密
byte[] keyBytes = decryptBASE64(privateKey);
// 取得公鑰
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = ECKeyFactory.INSTANCE;
ECPublicKey pubKey = (ECPublicKey) keyFactory
.generatePublic(x509KeySpec);
ECPublicKeySpec ecPublicKeySpec = new ECPublicKeySpec(pubKey.getW(),
pubKey.getParams());
// 對數據加密
// TODO Chipher不支持EC算法 未能實現
Cipher cipher = new NullCipher();
// Cipher.getInstance(ALGORITHM, keyFactory.getProvider());
cipher.init(Cipher.ENCRYPT_MODE, pubKey, ecPublicKeySpec.getParams());
return cipher.doFinal(data);
}
/**
* 取得私鑰
*
* @param keyMap
* @return
* @throws Exception
*/
public static String getPrivateKey(Map<String, Object> keyMap)
throws Exception {
Key key = (Key) keyMap.get(PRIVATE_KEY);
return encryptBASE64(key.getEncoded());
}
/**
* 取得公鑰
*
* @param keyMap
* @return
* @throws Exception
*/
public static String getPublicKey(Map<String, Object> keyMap)
throws Exception {
Key key = (Key) keyMap.get(PUBLIC_KEY);
return encryptBASE64(key.getEncoded());
}
/**
* 初始化密鑰
*
* @return
* @throws Exception
*/
public static Map<String, Object> 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);
// 公鑰
ECPublicKey publicKey = new ECPublicKeyImpl(g, ecParameterSpec);
BigInteger s = new BigInteger(
"1234006549323611672814741753598448348329118574063", 10);
// 私鑰
ECPrivateKey privateKey = new ECPrivateKeyImpl(s, ecParameterSpec);
Map<String, Object> keyMap = new HashMap<String, Object>(2);
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}
}
請注意上述代碼中的TODO內容，再次提醒注意，Chipher不支持EC算法 ，以上代碼僅供參考。Chipher、Signature、KeyPairGenerator、KeyAgreement、SecretKey均不支持EC算法。為了確保程序能夠正常執行，我們使用了NullCipher類，驗證程序。
照舊提供一個測試類：
Java代碼
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;
/**
*
* @author 梁棟
* @version 1.0
* @since 1.0
*/
public class ECCCoderTest {
@Test
public void test() throws Exception {
String inputStr = "abc";
byte[] data = inputStr.getBytes();
Map<String, Object> keyMap = ECCCoder.initKey();
String publicKey = ECCCoder.getPublicKey(keyMap);
String privateKey = ECCCoder.getPrivateKey(keyMap);
System.err.println("公鑰: \n" + publicKey);
System.err.println("私鑰： \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" + "解密後: " + outputStr);
assertEquals(inputStr, outputStr);
}
}
控制台輸出：
Console代碼
公鑰:
MEAwEAYHKoZIzj0CAQYFK4EEAAEDLAAEAv4TwFN7vBGsqgfXk95ObV5clO7oAokHD7BdOP9YMh8u
gAU21TjM2qPZ
私鑰：
MDICAQAwEAYHKoZIzj0CAQYFK4EEAAEEGzAZAgEBBBTYJsR3BN7TFw7JHcAHFkwNmfil7w==
加密前: abc
解密後: abc
