RAS工具类

原创
10/14 15:40
阅读数 9

在加解密过程中:

  1. 公钥:使用 X509EncodedKeySpec 先编码转换下
  2. 私钥: 使用 PKCS8EncodedKeySpec 先编码转换下
package cn.utrust.common.utils;

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;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 公钥私钥加密解密
 */
public class RSAUtil {

	private static final Logger log = LoggerFactory.getLogger(RSAUtil.class);

	/**
	 * 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,1024:117,2048:245
	 */
	private static final int MAX_ENCRYPT_BLOCK = 245;

	/**
	 * RSA最大解密密文大小,1024:128,2048:256
	 */
	private static final int MAX_DECRYPT_BLOCK = 256;

	/**
	 * RSA 位数 如果采用2048 上面最大加密和最大解密则须填写: 245 256
	 */
	private static final int INITIALIZE_LENGTH = 2048;

	/**
	 * 生成密钥对(公钥和私钥)
	 */
	public static Map<String, Object> genKeyPair() throws Exception {
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		keyPairGen.initialize(INITIALIZE_LENGTH);
		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;
	}

	/**
	 * 获取私钥
	 * @param keyMap 密钥对
	 */
	public static String getPrivateKey(Map<String, Object> keyMap) throws Exception {
		Key key = (Key) keyMap.get(PRIVATE_KEY);
		return Base64.encodeBase64String(key.getEncoded());
	}

	/**
	 * <p>
	 * 获取公钥
	 * </p>
	 *
	 * @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());
	}

	/**
	 * 公钥加密
	 */
	public static String encryptedData(String data, String PUBLICKEY) {
		try {
			data = Base64.encodeBase64String(encryptByPublicKey(data.getBytes("UTF-8"), PUBLICKEY));
		} catch (Exception e) {
			log.error("RSA加密出现异常:", e);
		}
		return data;
	}

	/**
	 * 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 = Base64.decodeBase64(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;
	}

	/**
	 * 私钥解密
	 */
	public static String decryptData(String data, String PRIVATEKEY) {
		String temp = "";
		try {
			byte[] rs = Base64.decodeBase64(data);
			byte[] decrytedByte = decryptByPrivateKey(rs, PRIVATEKEY);
			temp = new String(decrytedByte, "UTF-8");
		} catch (Exception e) {
			log.error("RSA解密出现异常:", e);
		}
		return temp;
	}

	/**
	 * 私钥解密
	 */
	public static byte[] decryptDataByteArray(String data, String PRIVATEKEY) {
		try {
			byte[] rs = Base64.decodeBase64(data);
			return decryptByPrivateKey(rs, PRIVATEKEY);
		} catch (Exception e) {
			log.error("RSA解密出现异常:", e);
		}
		return null;
	}

	/**
	 * <P>
	 * 私钥解密
	 * </p>
	 *
	 * @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 = Base64.decodeBase64(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;
	}

	public static void main(String[] args) throws Exception {
		Map<String, Object> keyMap = genKeyPair();
		System.out.println("public-key:\n" + getPublicKey(keyMap));
		System.out.println("private-key:\n" + getPrivateKey(keyMap));

	}
}

 

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