java RSA加密解密实现

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;

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;

/** *//**
 * 

* RSA公钥/私钥/签名工具包 *

*

* 罗纳德·李维斯特(Ron [R]ivest)、阿迪·萨莫尔(Adi [S]hamir)和伦纳德·阿德曼(Leonard [A]dleman) *

*

* 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 *

* * @author IceWee * @date 2012-4-26 * @version 1.0 */ 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(公钥和私钥) *

* * @return * @throws Exception */ public static Map 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 keyMap = new HashMap(2); 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 已加密数据 * @param privateKey 私钥(BASE64编码) * * @return * @throws Exception */ 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()); } /** *//** *

* 校验数字签名 *

* * @param data 已加密数据 * @param publicKey 公钥(BASE64编码) * @param sign 数字签名 * * @return * @throws Exception * */ 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)); } /** *//** *

* 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 = 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; // 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 = 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; // 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 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 = Base64Utils.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 = 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; // 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; } /** *//** *

* 获取私钥 *

* * @param keyMap 密钥对 * @return * @throws Exception */ public static String getPrivateKey(Map keyMap) throws Exception { Key key = (Key) keyMap.get(PRIVATE_KEY); return Base64Utils.encode(key.getEncoded()); } /** *//** *

* 获取公钥 *

* * @param keyMap 密钥对 * @return * @throws Exception */ public static String getPublicKey(Map keyMap) throws Exception { Key key = (Key) keyMap.get(PUBLIC_KEY); return Base64Utils.encode(key.getEncoded()); } }

Base64Utils.java
package security;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import it.sauronsoftware.base64.Base64;

/** *//**
 * 

* BASE64编码解码工具包 *

*

* 依赖javabase64-1.3.1.jar *

* * @author IceWee * @date 2012-5-19 * @version 1.0 */ public class Base64Utils { /** *//** * 文件读取缓冲区大小 */ private static final int CACHE_SIZE = 1024; /** *//** *

* BASE64字符串解码为二进制数据 *

* * @param base64 * @return * @throws Exception */ public static byte[] decode(String base64) throws Exception { return Base64.decode(base64.getBytes()); } /** *//** *

* 二进制数据编码为BASE64字符串 *

* * @param bytes * @return * @throws Exception */ public static String encode(byte[] bytes) throws Exception { return new String(Base64.encode(bytes)); } /** *//** *

* 将文件编码为BASE64字符串 *

*

* 大文件慎用,可能会导致内存溢出 *

* * @param filePath 文件绝对路径 * @return * @throws Exception */ public static String encodeFile(String filePath) throws Exception { byte[] bytes = fileToByte(filePath); return encode(bytes); } /** *//** *

* BASE64字符串转回文件 *

* * @param filePath 文件绝对路径 * @param base64 编码字符串 * @throws Exception */ public static void decodeToFile(String filePath, String base64) throws Exception { byte[] bytes = decode(base64); byteArrayToFile(bytes, filePath); } /** *//** *

* 文件转换为二进制数组 *

* * @param filePath 文件路径 * @return * @throws Exception */ public static byte[] fileToByte(String filePath) throws Exception { byte[] data = new byte[0]; File file = new File(filePath); if (file.exists()) { FileInputStream in = new FileInputStream(file); ByteArrayOutputStream out = new ByteArrayOutputStream(2048); byte[] cache = new byte[CACHE_SIZE]; int nRead = 0; while ((nRead = in.read(cache)) != -1) { out.write(cache, 0, nRead); out.flush(); } out.close(); in.close(); data = out.toByteArray(); } return data; } /** *//** *

* 二进制数据写文件 *

* * @param bytes 二进制数据 * @param filePath 文件生成目录 */ public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception { InputStream in = new ByteArrayInputStream(bytes); File destFile = new File(filePath); if (!destFile.getParentFile().exists()) { destFile.getParentFile().mkdirs(); } destFile.createNewFile(); OutputStream out = new FileOutputStream(destFile); byte[] cache = new byte[CACHE_SIZE]; int nRead = 0; while ((nRead = in.read(cache)) != -1) { out.write(cache, 0, nRead); out.flush(); } out.close(); in.close(); } }

 

RSATester.java

package security;

import java.util.Map;

public class RSATester {

    static String publicKey;
    static String privateKey;

    static {
        try {
            Map 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();
        }
    }
    
    public static void main(String[] args) throws Exception {
        test();
        testSign();
    }

    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);
    }

    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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