RSA加解密
- RSA加密介绍
- 生成密钥队生成密钥队
- 加解密
- 数字签名验证
RSA加密介绍：
RSA加密算法是一种非对称加密算法。在公开密钥加密和电子商业中RSA被广泛使用。RSA是1977年由罗纳德·李维斯特（Ron Rivest）、阿迪·萨莫尔（Adi Shamir）和伦纳德·阿德曼（Leonard Adleman）一起提出的。当时他们三人都在麻省理工学院工作。RSA就是他们三人姓氏开头字母拼在一起组成的。
1973年，在英国政府通讯总部工作的数学家克利福德·柯克斯（Clifford Cocks）在一个内部文件中提出了一个相同的算法，但他的发现被列入机密，一直到1997年才被发表。
对极大整数做因数分解的难度决定了RSA算法的可靠性。换言之，对一极大整数做因数分解愈困难，RSA算法愈可靠。假如有人找到一种快速因数分解的算法的话，那么用RSA加密的信息的可靠性就肯定会极度下降。但找到这样的算法的可能性是非常小的。今天只有短的RSA钥匙才可能被强力方式解破。到目前为止，世界上还没有任何可靠的攻击RSA算法的方式。只要其钥匙的长度足够长，用RSA加密的信息实际上是不能被解破的。
1983年麻省理工学院在美国为RSA算法申请了专利。这个专利2000年9月21日失效。由于该算法在申请专利前就已经被发表了，在世界上大多数其它地区这个专利权不被承认。
项目结构图
依赖配置:
代码示例：
package RSA;
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;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;
public class RSAUtils {
/**
* 加密算法RSA
*/
public static final String KEY_ALGORITHM = "RSA";
/**
* 签名算法
*/
public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
/**
* 获取公钥的key
*/
private static final String PUBLIC_KEY = "RSAPublicKey";
/**
* 获取私钥的key
*/
private static final String PRIVATE_KEY = "RSAPrivateKey";
/**
* RSA最大加密明文大小
*/
private static final int MAX_ENCRYPT_BLOCK = 117;
/**
* RSA最大解密密文大小
*/
private static final int MAX_DECRYPT_BLOCK = 128;
/**
* 生成密钥对（公钥和密钥）
*
* @return
* @throws Exception
*/
public static Map<String, Object> getKenPair() throws Exception {
// 指定加密算法
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
keyPairGen.initialize(1024);
// 获取密钥对
KeyPair keyPair = keyPairGen.generateKeyPair();
// 获取公钥
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
// 获取私钥
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
Map<String, Object> keyMap = new HashMap<String, Object>();
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}
/**
* 用私钥对信息生成数字签名
*
* @param data
* @param privateKey
* @return
* @throws Exception
*/
public static String sign(byte[] data, String privateKey) throws Exception {
// Base64解码
byte[] keyBytes = Base64.decodeBase64(privateKey);
// PKCS编码对象
PKCS8EncodedKeySpec pkcs8Encode = new PKCS8EncodedKeySpec(keyBytes);
// 算法工厂
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
// 密钥对象
PrivateKey privateKeyObj = keyFactory.generatePrivate(pkcs8Encode);
// 数字签名对象
Signature signture = Signature.getInstance(SIGNATURE_ALGORITHM);
// 密钥签名
signture.initSign(privateKeyObj);
// 加密
signture.update(data);
return Base64.encodeBase64String(signture.sign());
}
/**
* 用公钥校验签名
*
* @param data
* @param publicKey
* @param sign
* @return
* @throws Exception
*/
public static boolean verify(byte[] data, String publicKey, String sign) throws Exception {
// 解码
byte[] keyBytes = Base64.decodeBase64(publicKey);
// X509编码对象
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
// 算法工厂
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
// 公钥对象
PublicKey publicKeyObj = keyFactory.generatePublic(keySpec);
// 数字签名对象
Signature signture = Signature.getInstance(SIGNATURE_ALGORITHM);
// 公钥初始化
signture.initVerify(publicKeyObj);
signture.update(data);
return signture.verify(Base64.decodeBase64(sign));
}
/**
* 私钥解密
*
* @param encryptedData
* @param privateKey
* @return
* @throws Exception
*/
public static byte[] decryptedByPirvateKey(byte[] encryptedData, String privateKey) throws Exception {
// Base64解码
byte[] keyBytes = Base64.decodeBase64(privateKey);
// PKCS8编码对象
PKCS8EncodedKeySpec pkcs8EncodeSpec = new PKCS8EncodedKeySpec(keyBytes);
// 算法工厂
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateK = keyFactory.generatePrivate(pkcs8EncodeSpec);
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;
// 对数据进行分段解密
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[] decrytedData = out.toByteArray();
out.close();
return decrytedData;
}
/**
* 公钥解密
*
* @param encryptedData
* @param publicKey
* @return
* @throws Exception
*/
public static byte[] decryptedByPublicKey(byte[] encryptedData, String publicKey) throws Exception {
// Base64解码
byte[] keyBytes = Base64.decodeBase64(publicKey);
// X509编码对象
X509EncodedKeySpec x509EncodeSpec = new X509EncodedKeySpec(keyBytes);
// 算法工厂
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
// 公钥key
Key publicKeyObj = keyFactory.generatePublic(x509EncodeSpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, publicKeyObj);
ByteArrayOutputStream out = new ByteArrayOutputStream();
int inputLen = encryptedData.length;
int offset = 0;
byte[] cache;
int i = 0;
// 对数据分段解密
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;
}
/**
* 公钥加密
*
* @param data
* @param publicKey
* @return
* @throws Exception
*/
public static byte[] encryptedDataByPublicKey(byte[] data, String publicKey) throws Exception {
// 解码
byte[] keyBytes = Base64.decodeBase64(publicKey);
X509EncodedKeySpec x509 = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicKeyObj = keyFactory.generatePublic(x509);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, publicKeyObj);
int inputLen = data.length;
int offset = 0;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int i = 0;
byte[] cache;
// 对数据进行分段加密
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;
}
/**
* 私钥加密
*
* @param data
* @param privateKey
* @return
* @throws Exception
*/
public static byte[] encryptedDataByPrivateKey(byte[] data, String privateKey) throws Exception {
byte[] keyBytes = Base64.decodeBase64(privateKey);
PKCS8EncodedKeySpec pkcs8Spec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateKeyObj = keyFactory.generatePrivate(pkcs8Spec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, privateKeyObj);
int inputLen = data.length;
int offset = 0;
int i = 0;
ByteArrayOutputStream out = new ByteArrayOutputStream();
byte[] cache;
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;
}
/**
* 获取私钥
*
* @param map
* @return
*/
public static String getPrivateKey(Map<String, Object> map) throws Exception {
Key key = (Key) map.get(PRIVATE_KEY);
return Base64.encodeBase64String(key.getEncoded());
}
/**
* 获取公钥
*
* @param map
* @return
* @throws Exception
*/
public static String getPublicKey(Map<String, Object> map) throws Exception {
Key key = (Key) map.get(PUBLIC_KEY);
return Base64.encodeBase64String(key.getEncoded());
}
}
测试类代码如下：
package RSA;
import java.util.Map;
public class RSATest {
static String publicKey;
static String privateKey;
static {
try {
Map<String, Object> keyMap = RSAUtils.getKenPair();
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();
}
}
public static void main(String[] args) throws Exception {
// test();
// testSign();
testHttpSign();
}
static void test() throws Exception {
System.out.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.encryptedDataByPublicKey(data, publicKey);
System.out.println("加密后文字：\r\n" + new String(encodedData));
byte[] decodedData = RSAUtils.decryptedByPirvateKey(encodedData, privateKey);
String target = new String(decodedData);
System.out.println("解密后文字: \r\n" + target);
}
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.encryptedDataByPrivateKey(data, privateKey);
System.out.println("加密后：\r\n" + new String(encodedData));
byte[] decodedData = RSAUtils.decryptedByPublicKey(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);
}
static void testHttpSign() throws Exception {
System.out.println("---------------私钥加密----------------------------------公钥加密----------------------");
String param = "id=1&name=张三";
System.out.println("原始内容：\n" + param);
byte[] encodedData = RSAUtils.encryptedDataByPrivateKey(param.getBytes(), privateKey);
System.out.println("加密后：" + encodedData);
byte[] decodedData = RSAUtils.decryptedByPublicKey(encodedData, publicKey);
System.out.println("解密后：" + new String(decodedData));
System.out.println("---------------私钥签名----------------------------------公钥验签----------------------");
String sign = RSAUtils.sign(encodedData, privateKey);
System.err.println("签名：" + sign);
boolean status = RSAUtils.verify(encodedData, publicKey, sign);
System.err.println("签名验证结果：" + status);
}
}
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