该工具类中用到了BASE64,需要借助第三方类库:javabase64-1.3.1.jar 下载地址:http://download.csdn.net/detail/centralperk/5025595
注意: RSA加密明文最大长度117字节,解密要求密文最大长度为128字节,所以在加密和解密的过程中需要分块进行。 RSA加密对明文的长度是有限制的,如果加密数据过大会抛出如下异常:
- Exception in thread "main" javax.crypto.IllegalBlockSizeException: Data must not be longer than 117 bytes
- at com.sun.crypto.provider.RSACipher.a(DashoA13*..)
- at com.sun.crypto.provider.RSACipher.engineDoFinal(DashoA13*..)
- at javax.crypto.Cipher.doFinal(DashoA13*..)
RSAUtils.java
- package security;
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- import java.io.ByteArrayOutputStream;
- import java.security.Key;
- import java.security.KeyFactory;
- import java.security.KeyPair;
- import java.security.KeyPairGenerator;
- import java.security.PrivateKey;
- import java.security.PublicKey;
- import java.security.Signature;
- import java.security.interfaces.RSAPrivateKey;
- import java.security.interfaces.RSAPublicKey;
- import java.security.spec.PKCS8EncodedKeySpec;
- import java.security.spec.X509EncodedKeySpec;
- import java.util.HashMap;
- import java.util.Map;
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- import javax.crypto.Cipher;
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- public class RSAUtils {
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- public static final String KEY_ALGORITHM = "RSA";
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- public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
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- private static final String PUBLIC_KEY = "RSAPublicKey";
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- private static final String PRIVATE_KEY = "RSAPrivateKey";
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- private static final int MAX_ENCRYPT_BLOCK = 117;
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- private static final int MAX_DECRYPT_BLOCK = 128;
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- public static Map<String, Object> genKeyPair() throws Exception {
- KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
- keyPairGen.initialize(1024);
- KeyPair keyPair = keyPairGen.generateKeyPair();
- RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
- RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
- Map<String, Object> keyMap = new HashMap<String, Object>(2);
- keyMap.put(PUBLIC_KEY, publicKey);
- keyMap.put(PRIVATE_KEY, privateKey);
- return keyMap;
- }
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- public static String sign(byte[] data, String privateKey) throws Exception {
- byte[] keyBytes = Base64Utils.decode(privateKey);
- PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
- Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
- signature.initSign(privateK);
- signature.update(data);
- return Base64Utils.encode(signature.sign());
- }
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- public static boolean verify(byte[] data, String publicKey, String sign)
- throws Exception {
- byte[] keyBytes = Base64Utils.decode(publicKey);
- X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- PublicKey publicK = keyFactory.generatePublic(keySpec);
- Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
- signature.initVerify(publicK);
- signature.update(data);
- return signature.verify(Base64Utils.decode(sign));
- }
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- public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
- throws Exception {
- byte[] keyBytes = Base64Utils.decode(privateKey);
- PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.DECRYPT_MODE, privateK);
- int inputLen = encryptedData.length;
- ByteArrayOutputStream out = new ByteArrayOutputStream();
- int offSet = 0;
- byte[] cache;
- int i = 0;
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- while (inputLen - offSet > 0) {
- if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
- cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
- } else {
- cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
- }
- out.write(cache, 0, cache.length);
- i++;
- offSet = i * MAX_DECRYPT_BLOCK;
- }
- byte[] decryptedData = out.toByteArray();
- out.close();
- return decryptedData;
- }
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- public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
- throws Exception {
- byte[] keyBytes = Base64Utils.decode(publicKey);
- X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key publicK = keyFactory.generatePublic(x509KeySpec);
- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.DECRYPT_MODE, publicK);
- int inputLen = encryptedData.length;
- ByteArrayOutputStream out = new ByteArrayOutputStream();
- int offSet = 0;
- byte[] cache;
- int i = 0;
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- while (inputLen - offSet > 0) {
- if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
- cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
- } else {
- cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
- }
- out.write(cache, 0, cache.length);
- i++;
- offSet = i * MAX_DECRYPT_BLOCK;
- }
- byte[] decryptedData = out.toByteArray();
- out.close();
- return decryptedData;
- }
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- public static byte[] encryptByPublicKey(byte[] data, String publicKey)
- throws Exception {
- byte[] keyBytes = Base64Utils.decode(publicKey);
- X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key publicK = keyFactory.generatePublic(x509KeySpec);
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- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.ENCRYPT_MODE, publicK);
- int inputLen = data.length;
- ByteArrayOutputStream out = new ByteArrayOutputStream();
- int offSet = 0;
- byte[] cache;
- int i = 0;
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- while (inputLen - offSet > 0) {
- if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
- cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
- } else {
- cache = cipher.doFinal(data, offSet, inputLen - offSet);
- }
- out.write(cache, 0, cache.length);
- i++;
- offSet = i * MAX_ENCRYPT_BLOCK;
- }
- byte[] encryptedData = out.toByteArray();
- out.close();
- return encryptedData;
- }
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- public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
- throws Exception {
- byte[] keyBytes = Base64Utils.decode(privateKey);
- PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.ENCRYPT_MODE, privateK);
- int inputLen = data.length;
- ByteArrayOutputStream out = new ByteArrayOutputStream();
- int offSet = 0;
- byte[] cache;
- int i = 0;
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- while (inputLen - offSet > 0) {
- if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
- cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
- } else {
- cache = cipher.doFinal(data, offSet, inputLen - offSet);
- }
- out.write(cache, 0, cache.length);
- i++;
- offSet = i * MAX_ENCRYPT_BLOCK;
- }
- byte[] encryptedData = out.toByteArray();
- out.close();
- return encryptedData;
- }
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- public static String getPrivateKey(Map<String, Object> keyMap)
- throws Exception {
- Key key = (Key) keyMap.get(PRIVATE_KEY);
- return Base64Utils.encode(key.getEncoded());
- }
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- public static String getPublicKey(Map<String, Object> keyMap)
- throws Exception {
- Key key = (Key) keyMap.get(PUBLIC_KEY);
- return Base64Utils.encode(key.getEncoded());
- }
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- }
Base64Utils.java
RSATester.java
- package security;
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- import java.util.Map;
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- public class RSATester {
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- static String publicKey;
- static String privateKey;
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- static {
- try {
- Map<String, Object> keyMap = RSAUtils.genKeyPair();
- publicKey = RSAUtils.getPublicKey(keyMap);
- privateKey = RSAUtils.getPrivateKey(keyMap);
- System.err.println("公钥: \n\r" + publicKey);
- System.err.println("私钥: \n\r" + privateKey);
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
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- public static void main(String[] args) throws Exception {
- test();
- testSign();
- }
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- static void test() throws Exception {
- System.err.println("公钥加密——私钥解密");
- String source = "这是一行没有任何意义的文字,你看完了等于没看,不是吗?";
- System.out.println("\r加密前文字:\r\n" + source);
- byte[] data = source.getBytes();
- byte[] encodedData = RSAUtils.encryptByPublicKey(data, publicKey);
- System.out.println("加密后文字:\r\n" + new String(encodedData));
- byte[] decodedData = RSAUtils.decryptByPrivateKey(encodedData, privateKey);
- String target = new String(decodedData);
- System.out.println("解密后文字: \r\n" + target);
- }
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- static void testSign() throws Exception {
- System.err.println("私钥加密——公钥解密");
- String source = "这是一行测试RSA数字签名的无意义文字";
- System.out.println("原文字:\r\n" + source);
- byte[] data = source.getBytes();
- byte[] encodedData = RSAUtils.encryptByPrivateKey(data, privateKey);
- System.out.println("加密后:\r\n" + new String(encodedData));
- byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, publicKey);
- String target = new String(decodedData);
- System.out.println("解密后: \r\n" + target);
- System.err.println("私钥签名——公钥验证签名");
- String sign = RSAUtils.sign(encodedData, privateKey);
- System.err.println("签名:\r" + sign);
- boolean status = RSAUtils.verify(encodedData, publicKey, sign);
- System.err.println("验证结果:\r" + status);
- }
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- }
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