RSA非对称加密算法Java实现
package rsa;import java.io.IOException;import java.security.InvalidKeyException;import java.security.Key;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.NoSuchAlgorithmException;import java.security.PrivateKey;import java.security.PublicKey;import java.security.spec.InvalidKeySpecException;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import javax.crypto.BadPaddingException;import javax.crypto.Cipher;import javax.crypto.IllegalBlockSizeException;import sun.misc.BASE64Decoder;import sun.misc.BASE64Encoder;@SuppressWarnings({ "restriction" })public class RSAUtils {/** 私有构造方法 */private RSAUtils() {super();}private static final Cipher CIPHER;static {try {CIPHER = Cipher.getInstance("RSA");} catch (Throwable e) {throw new InternalError(e.getMessage());}}//~ -----------------------------------------/** * 生成私钥和公钥 * * @return KeyPair */public static KeyPair generateKeyPair() {return generateKeyPair(1024);}/** * 生成私钥和公钥 * * @param keySize 密钥长度 * @return KeyPair */public static KeyPair generateKeyPair(int keySize) {KeyPairGenerator keyPairGen = null;try {keyPairGen = KeyPairGenerator.getInstance("RSA");} catch (NoSuchAlgorithmException e) {throw new InternalError(e.getMessage());}keyPairGen.initialize(keySize);return keyPairGen.generateKeyPair();}/** * 从KeyPair中获得公钥 * * @param keyPair KeyPair * @return 公钥 */public static PublicKey getPublicKey(KeyPair keyPair) {if (keyPair == null) {return null;}return keyPair.getPublic();}/** * 从KeyPair中获得私钥 * * @param keyPair KeyPair * @return 私钥 */public static PrivateKey getPrivateKey(KeyPair keyPair) {if (keyPair == null) {return null;}return keyPair.getPrivate();}/** * 讲公钥或私钥转换为String * * @param key 公钥/私钥 * @return 字符串 */public static String getKeyString(Key key) {if (key == null) {return null;}byte[] keyBytes = key.getEncoded();String s = (new BASE64Encoder()).encode(keyBytes);return s;}/** * 得到公钥 * * @param key * 密钥字符串（经过base64编码） * @throws Exception */public static PublicKey getPublicKey(String key) {byte[] keyBytes = null;try {keyBytes = (new BASE64Decoder()).decodeBuffer(key);} catch (IOException e) {throw new IllegalArgumentException(e.getMessage(), e);}X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = null;try {keyFactory = KeyFactory.getInstance("RSA");} catch (NoSuchAlgorithmException e) {throw new InternalError(e.getMessage());}PublicKey publicKey = null;try {publicKey = keyFactory.generatePublic(keySpec);} catch (InvalidKeySpecException e) {throw new IllegalArgumentException(e.getMessage(), e);}return publicKey;}/** * 得到私钥 * * @param key * 密钥字符串（经过base64编码） * @throws Exception */public static PrivateKey getPrivateKey(String key) {byte[] keyBytes;try {keyBytes = (new BASE64Decoder()).decodeBuffer(key);} catch (IOException e) {throw new IllegalArgumentException(e.getMessage(), e);}PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = null;try {keyFactory = KeyFactory.getInstance("RSA");} catch (NoSuchAlgorithmException e) {throw new InternalError(e.getMessage());}PrivateKey privateKey = null;try {privateKey = keyFactory.generatePrivate(keySpec);} catch (InvalidKeySpecException e) {throw new IllegalArgumentException(e.getMessage(), e);}return privateKey;}/** * 加密数据 * * @param data 原文 * @param key 公钥/私钥 * @return 密文 */public static byte[] encrypt(byte[] data, Key key) {try {CIPHER.init(Cipher.ENCRYPT_MODE, key);} catch (InvalidKeyException e) {throw new IllegalArgumentException(e.getMessage(), e);}byte[] result = null;try {result = CIPHER.doFinal(data);} catch (IllegalBlockSizeException e) {throw new IllegalArgumentException(e.getMessage(), e);} catch (BadPaddingException e) {throw new IllegalArgumentException(e.getMessage(), e);}return result;}/** * 解密数据 * * @param data 密文 * @param key 公钥/私钥 * @return 原文 */public static byte[] decrypt(byte[] data, Key key) {try {CIPHER.init(Cipher.DECRYPT_MODE, key);} catch (InvalidKeyException e) {throw new IllegalArgumentException(e.getMessage(), e);}byte[] result = null;try {result = CIPHER.doFinal(data);} catch (IllegalBlockSizeException e) {throw new IllegalArgumentException(e.getMessage(), e);} catch (BadPaddingException e) {throw new IllegalArgumentException(e.getMessage(), e);}return result;}}@Overridepublic String encryptPassword(String password) {if (password == null) {return null;}byte[] data = RSAUtils.encrypt(password.getBytes(), publicKey);return Base64.encodeBase64URLSafeString(data);}@Overridepublic String decryptPassword(String encryptedPassword) {if (encryptedPassword == null) {return null;}byte[] data = Base64.decodeBase64(encryptedPassword);return new String(RSAUtils.decrypt(data, privateKey));}