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。在軟件註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。 如果想要獲得ECC算法實現,需要調用硬件完成加密/解密(ECC算法相當耗費資源,如果單純使用CPU進行加密/解密,效率低下),涉及到Java Card領域,PKCS#11。 其實,PKCS#11配置很簡單,但缺乏硬件設備,無法嘗試!
儘管如此,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)
- 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 樑棟
- * @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。爲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:
- 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 樑棟
- * @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);
- }
- }
控制檯輸出:
- 公鑰:
- MEAwEAYHKoZIzj0CAQYFK4EEAAEDLAAEAv4TwFN7vBGsqgfXk95ObV5clO7oAokHD7BdOP9YMh8u
- gAU21TjM2qPZ
- 私鑰:
- MDICAQAwEAYHKoZIzj0CAQYFK4EEAAEEGzAZAgEBBBTYJsR3BN7TFw7JHcAHFkwNmfil7w==
- 加密前: abc
- 解密後: abc