· RSA算法简介
RSA公开密钥密码体制是一种使用不同的加密密钥与解密密钥,“由已知加密密钥推导出解密密钥在计算上是不可行的”密码体制。
在公开密钥密码体制中,加密密钥(即公开密钥)PK是公开信息,而解密密钥(即秘密密钥)SK是需要保密的。加密算法E和解密算法D也都是公开的。虽然解密密钥SK是由公开密钥PK决定的,但却不能根据PK计算出SK。
RSA允许你选择公钥的大小。512位的密钥被视为不安全的;768位的密钥不用担心受到除了国家安全管理(NSA)外的其他事物的危害;1024位的密钥几乎是安全的。
关于RSA概念性的内容不做过多介绍,大家可以自行百度。
· Maven 依赖
工具类对于加密后使用Base64进行编码,所以需要依赖Apache Commons Codec。
<dependency>
<groupId>commons-codecgroupId>
<artifactId>commons-codecartifactId>
<version>1.9version>
dependency>
· 工具类实现
package com.arhorchin.securitit.enordecryption.rsa;
import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
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;
/**
* @author Securitit.
* @version 1.0.
* @note RSA公钥/私钥/签名工具包.
* 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式.
* 由于非对称加密速度极其缓慢,一般文件不使用它来加密而是使用对称加密.
* 非对称加密算法可以用来对对称加密的密钥加密,这样保证密钥的安全也就保证了数据的安全.
*/
public class RSAUtil {
/**
* 加密算法RSA.
*/
public static final String KEY_ALGORITHM = "RSA";
/**
* 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;
/**
* RSA密钥长度必须是64的倍数,在512~65536之间。默认是1024.
*/
public static final int KEY_SIZE = 1024;
/**
* 生成密钥对(公钥和私钥).
* @return .
* @throws Exception .
*/
public static Map<String, Object> genKeyPair() throws Exception {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
keyPairGen.initialize(KEY_SIZE);
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;
}
/**
* 获取公钥.
* @param keyMap 密钥对.
* @return .
* @throws Exception .
*/
public static String getPublicKey(Map<String, Object> keyMap) throws Exception {
Key key = (Key) keyMap.get(PUBLIC_KEY);
return Base64.encodeBase64String(key.getEncoded());
}
/**
* 获取私钥.
* @param keyMap 密钥对.
* @return .
* @throws Exception .
*/
public static String getPrivateKey(Map<String, Object> keyMap) throws Exception {
Key key = (Key) keyMap.get(PRIVATE_KEY);
return Base64.encodeBase64String(key.getEncoded());
}
/**
* 公钥加密.
* @param data 源数据.
* @param publicKey 公钥(BASE64编码).
* @return .
* @throws Exception .
*/
public static byte[] encryptByPublicKey(byte[] data, String publicKey) throws Exception {
byte[] keyBytes = new Base64().decode(publicKey);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicK = keyFactory.generatePublic(x509KeySpec);
// 对数据加密
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;
// 对数据分段加密
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 源数据.
* @param privateKey 私钥(BASE64编码).
* @return .
* @throws Exception .
*/
public static byte[] encryptByPrivateKey(byte[] data, String privateKey) throws Exception {
byte[] keyBytes = new Base64().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;
// 对数据分段加密
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;
}
/**
* 公钥解密.
* @param encryptedData 已加密数据.
* @param publicKey 公钥(BASE64编码).
* @return .
* @throws Exception .
*/
public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) throws Exception {
byte[] keyBytes = new Base64().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;
// 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;
}
/**
* 私钥解密.
* @param encryptedData 已加密数据.
* @param privateKey 私钥(BASE64编码).
* @return .
* @throws Exception .
*/
public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey) throws Exception {
byte[] keyBytes = new Base64().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;
// 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;
}
}
· 密钥生成测试类如下:
package com.arhorchin.securitit.enordecryption.rsa;
import java.util.Map;
import com.arhorchin.securitit.enordecryption.rsa.RSAUtil;
/**
* @author Securitit.
* @note RSA非对称密钥对生成.
*/
public class RsaKeyPairTester {
public static void main(String[] args) throws Exception {
Map<String, Object> keyPairMap = null;
String publicKeyStr = null;
String privateKeyStr = null;
keyPairMap = RSAUtil.genKeyPair();
publicKeyStr = RSAUtil.getPublicKey(keyPairMap);
privateKeyStr = RSAUtil.getPrivateKey(keyPairMap);
System.out.println("公钥:" + publicKeyStr);
System.out.println("私钥:" + privateKeyStr);
}
}
· 密钥生成输出结果:
公钥:MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCrEC2uiS37eTAGlw4obsYIQ64c7UZgqiLETjv1ddU729kIQuLDOS+iq/RGoFsfPDSNfjTCBFMcYyFw3L2Ee9lsVGbfupztf1Ni9ZgVzlQ1d2v9xi15Ol/DGytMGxEmSIWPD8dL7yrQ9Cw9MlX1gT1YYFjB0M0FgwmBqZ7xv7CjaQIDAQAB
私钥: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
· 加解密测试类如下:
package com.arhorchin.securitit.enordecryption.rsa;
import org.apache.commons.codec.binary.Base64;
import com.arhorchin.securitit.enordecryption.charset.Characters;
/**
* @author Securitit.
* @note RSAUtil测试类.
*/
public class RSAUtilTester {
/**
* 公钥.
*/
private static String PUBLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCrEC2uiS37eTAGlw4obsYIQ64c7UZgqiLETjv1ddU729kIQuLDOS+iq/RGoFsfPDSNfjTCBFMcYyFw3L2Ee9lsVGbfupztf1Ni9ZgVzlQ1d2v9xi15Ol/DGytMGxEmSIWPD8dL7yrQ9Cw9MlX1gT1YYFjB0M0FgwmBqZ7xv7CjaQIDAQAB";
/**
* 私钥.
*/
private static String PRIVATE_KEY = "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";
public static void main(String[] args) throws Exception {
String plaintext = null;
byte[] cipherBts = null;
String ciphertext = null;
byte[] dePlainBts = null;
String dePlaintext = null;
/********************************* 公钥加密、私钥解密 ************************************/
plaintext = "这是一段数据原文-公钥原文.";
// 公钥进行加密示例.
cipherBts = RSAUtil.encryptByPublicKey(plaintext.getBytes(Characters.UTF8), PUBLIC_KEY);
ciphertext = Base64.encodeBase64String(cipherBts);
System.out.println("公钥加密密文:" + ciphertext);
// 私钥进行解密示例.
dePlainBts = RSAUtil.decryptByPrivateKey(Base64.decodeBase64(ciphertext), PRIVATE_KEY);
dePlaintext = new String(dePlainBts, Characters.UTF8);
System.out.println("私钥解密明文:" + dePlaintext);
/********************************* 私钥加密、公钥解密 ************************************/
plaintext = "这是一段数据原文-私钥原文.";
// 私钥进行加密示例.
cipherBts = RSAUtil.encryptByPrivateKey(plaintext.getBytes(Characters.UTF8), PRIVATE_KEY);
ciphertext = Base64.encodeBase64String(cipherBts);
System.out.println("私钥加密密文:" + ciphertext);
// 公钥进行解密示例.
dePlainBts = RSAUtil.decryptByPublicKey(Base64.decodeBase64(ciphertext), PUBLIC_KEY);
dePlaintext = new String(dePlainBts, Characters.UTF8);
System.out.println("公钥解密明文:" + dePlaintext);
}
}
· 加解密输出结果:
公钥加密密文:fslkNblfclqJQ0cTq5YjTGOOvioatFcbOJd8lFt2qMAWzyfUI/9Cish6VuVIRo4AogFFkJGYg7MtMr48YTdIdnwNpieOxh1emzEOTnR/rCwPvQG7rk7L6vntkwy1d7s/J3B1TcsY+0/52Gna702ksZgYjvNmry9dKJteAZSWnY0=
私钥解密明文:这是一段数据原文-公钥原文.
私钥加密密文:La+NYTDI3OAH4AofUh0BHY4u+NwtImPeTDBxsSKJZN1AtmLAnnxH2BPbHz/hiraHTbQK0QSsuUbW/vFOItk7x117caeQJaZm/MOHRBKlRlUJHKKa1Mc/2Hr7bFd5jpn7493PWuvJgBZw3MT7P6FyLaqVK+EGjzx7f+If+SvaelE=
公钥解密明文:这是一段数据原文-私钥原文.
· 总结
算法实现都很类似,本文只是对算法实现做了整理,在Maven依赖引入的情况下,RSAUtil已经做了简单测试,可以直接使用。