RSA非对称加密解，支持分段加密解密、(公钥加密，私钥解密)、(私钥加密，公钥解密)

运行Main方法测试

import org.apache.commons.codec.binary.Base64;import javax.crypto.Cipher;
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;/*** RSA加解密工具类*/
public class RSAUtil {/*** 加密算法*/private static final String ALGORITHM = "RSA";/*** 填充方式*/private static final String PADDING_FORMAT = "RSA/ECB/PKCS1Padding";/*** 明文块最大值*/private static final int MAX_ENCRYPT_BLOCK = 117;/*** 密文块最大值*/private static final int MAX_DECRYPT_BLOCK = 128;/*** 字符编码*/public static final String CHARSET_UTF_8 = "UTF-8";/*** 生成密钥对** @return 包含公钥和私钥的Map* @throws Exception 如果生成密钥对失败*/private static Map<String, String> generateKeyPair() throws Exception {KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);keyPairGenerator.initialize(1024);KeyPair keyPair = keyPairGenerator.generateKeyPair();RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();Map<String, String> keyMap = new HashMap<>(2);keyMap.put("RSAPublicKey", Base64.encodeBase64String(publicKey.getEncoded()));keyMap.put("RSAPrivateKey", Base64.encodeBase64String(privateKey.getEncoded()));return keyMap;}/*** 使用公钥加密** @param text      明文* @param publicKey 公钥* @param charset   字符编码* @return 加密后的字符串（base64）* @throws Exception 如果加密失败*/public static String encrypt(String text, String publicKey, String charset) throws Exception {byte[] data = text.getBytes(charset);byte[] keyBytes = Base64.decodeBase64(publicKey);X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);Key key = keyFactory.generatePublic(x509KeySpec);return getCipherText(data, key, Cipher.ENCRYPT_MODE, MAX_ENCRYPT_BLOCK, charset);}/*** 使用私钥解密** @param ciphertext 密文（base64）* @param privateKey 私钥* @param charset    字符编码* @return 解密后的字符串* @throws Exception 如果解密失败*/public static String decrypt(String ciphertext, String privateKey, String charset) throws Exception {byte[] data = Base64.decodeBase64(ciphertext);byte[] keyBytes = Base64.decodeBase64(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);Key key = keyFactory.generatePrivate(pkcs8KeySpec);return getCipherText(data, key, Cipher.DECRYPT_MODE, MAX_DECRYPT_BLOCK, charset);}/*** 使用私钥加密** @param text       明文* @param privateKey 私钥* @param charset    字符编码* @return 加密后的字符串（base64）* @throws Exception 如果加密失败*/public static String encryptWithPrivateKey(String text, String privateKey, String charset) throws Exception {byte[] data = text.getBytes(charset);byte[] keyBytes = Base64.decodeBase64(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);Key key = keyFactory.generatePrivate(pkcs8KeySpec);return getCipherText(data, key, Cipher.ENCRYPT_MODE, MAX_ENCRYPT_BLOCK, charset);}/*** 使用公钥解密** @param ciphertext 密文（base64）* @param publicKey  公钥* @param charset    字符编码* @return 解密后的字符串* @throws Exception 如果解密失败*/public static String decryptWithPublicKey(String ciphertext, String publicKey, String charset) throws Exception {byte[] data = Base64.decodeBase64(ciphertext);byte[] keyBytes = Base64.decodeBase64(publicKey);X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);Key key = keyFactory.generatePublic(x509KeySpec);return getCipherText(data, key, Cipher.DECRYPT_MODE, MAX_DECRYPT_BLOCK, charset);}/*** 获取加密或解密后的文本** @param data     待处理的数据* @param key      密钥* @param mode     模式（加密或解密）* @param maxBlock 每次处理的最大数据块大小* @param charset  字符编码* @return 处理后的文本* @throws Exception 如果处理失败*/private static String getCipherText(byte[] data, Key key, int mode, int maxBlock, String charset) throws Exception {Cipher cipher = Cipher.getInstance(PADDING_FORMAT);cipher.init(mode, key);int length = data.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 对数据分段处理while (length - offSet > 0) {int len = Math.min(length - offSet, maxBlock);cache = cipher.doFinal(data, offSet, len);out.write(cache, 0, cache.length);i++;offSet = i * maxBlock;}byte[] cipherBytes = out.toByteArray();out.close();if (mode == Cipher.ENCRYPT_MODE) {return Base64.encodeBase64String(cipherBytes); // 返回加密后的base64字符串} else {return new String(cipherBytes, charset); // 返回解密后的字符串}}public static void main(String[] args) {try {// 创建密钥对Map<String, String> keys = generateKeyPair();System.out.println("==================================================生成Public Key======================================================");String pubKey = keys.get("RSAPublicKey");System.out.println(pubKey);System.out.println();System.out.println("==================================================生成Private Key======================================================");String priKey = keys.get("RSAPrivateKey");System.out.println(priKey);System.out.println();// 测试加密文本String text = "123";System.out.println("==================================================公钥加密，私钥解密======================================================");String ciphertext = encrypt(text, pubKey, CHARSET_UTF_8);System.out.println("明文：" + text);System.out.println("加密后文本：" + ciphertext);System.out.println("解密后文本：" + decrypt(ciphertext, priKey, CHARSET_UTF_8));System.out.println();System.out.println("==================================================私钥加密，公钥解密======================================================");ciphertext = encryptWithPrivateKey(text, priKey, CHARSET_UTF_8);System.out.println("明文：" + text);System.out.println("加密后文本：" + ciphertext);System.out.println("解密后文本：" + decryptWithPublicKey(ciphertext, pubKey, CHARSET_UTF_8));} catch (Exception e) {e.printStackTrace();}}
}