java rsa加密

为了保证信息传输的安全性，需要对重要数据进行加密传输，本文提供了java的rsa加密方法供参考。

package test.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.Base64;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

public class RSAUtils {

	public static final String KEY_ALGORITHM = "RSA";
	public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
	private static final String PUBLIC_KEY = "RSAPublicKey";
	private static final String PRIVATE_KEY = "RSAPrivateKey";
	private static final int MAX_ENCRYPT_BLOCK = 117;
	private static final int MAX_DECRYPT_BLOCK = 128;

	/**
	 * 获得公钥、私钥
	 * 
	 * @return
	 * @throws Exception
	 */
	public static Map<String, Object> 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<String, Object> keyMap = new HashMap<String, Object>(2);
		keyMap.put(PUBLIC_KEY, publicKey);
		keyMap.put(PRIVATE_KEY, privateKey);

		return keyMap;
	}

	/**
	 * 签名
	 * @param data
	 * @param privateKey
	 * @return
	 * @throws Exception
	 */
	public static String sign(byte[] data, String privateKey) throws Exception {

		byte[] keyBytes = Base64.getDecoder().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 Base64.getEncoder().encodeToString(signature.sign());
	}

	/**
	 * 验证签名
	 * @param data
	 * @param publicKey
	 * @param sign
	 * @return
	 * @throws Exception
	 */
	public static boolean verify(byte[] data, String publicKey, String sign)
			throws Exception {

		byte[] keyBytes = Base64.getDecoder().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(Base64.getDecoder().decode(sign));
	}

	/**
	 * 私钥解密
	 * 
	 * @param encryptedData
	 * @param privateKey
	 * @return
	 * @throws Exception
	 */
	public static byte[] decryptByPrivateKey(byte[] encryptedData,
			String privateKey) throws Exception {

		byte[] keyBytes = Base64.getDecoder().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;
		int i = 0;
		byte[] cache;
		byte[] decryptedData;

		try {
			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;
			}
			decryptedData = out.toByteArray();
		} catch (Exception e) {
			throw e;
		} finally {
			out.close();
		}

		return decryptedData;
	}

	/**
	 * 公钥加密
	 * 
	 * @param data
	 * @param publicKey
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptByPublicKey(byte[] data, String publicKey)
			throws Exception {

		byte[] keyBytes = Base64.getDecoder().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.ENCRYPT_MODE, publicK);

		int inputLen = data.length;
		ByteArrayOutputStream out = new ByteArrayOutputStream();

		int offSet = 0;
		int i = 0;
		byte[] cache;
		byte[] encryptedData;

		try {
			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;
			}
			encryptedData = out.toByteArray();
		} catch (Exception e) {
			throw e;
		} finally {
			out.close();
		}
		return encryptedData;
	}

	/**
	 * 获得私钥
	 * 
	 * @param keyMap
	 * @return
	 * @throws Exception
	 */
	public static String getPrivateKey(final Map<String, Object> keyMap)
			throws Exception {
		Key key = (Key) keyMap.get(PRIVATE_KEY);
		return Base64.getEncoder().encodeToString(key.getEncoded());
	}

	/**
	 * 获得公钥
	 * 
	 * @param keyMap
	 * @return
	 * @throws Exception
	 */
	public static String getPublicKey(final Map<String, Object> keyMap)
			throws Exception {
		Key key = (Key) keyMap.get(PUBLIC_KEY);
		return Base64.getEncoder().encodeToString(key.getEncoded());
	}
}

外面再封装一层。

package test.rsa;

import java.util.Base64;

public class RSADecrypter {

	/**
	 * 私钥解密
	 * @param encryptedDate
	 * @param privateKey
	 * @return
	 * @throws Exception
	 */
	public static String decryptByPrivateKey(String encryptedDate, String privateKey) throws Exception {
		byte[] byte_data = Base64.getDecoder().decode(encryptedDate);
		byte[] decryptedData = RSAUtils.decryptByPrivateKey(byte_data, privateKey);
		return new String(decryptedData);
	}

	/**
	 * 公钥加密
	 * @param mes
	 * @param publishKey
	 * @return
	 * @throws Exception
	 */
	public static String encryptByPublishKey(String mes, String publishKey) throws Exception {
		byte[] encryptedData = RSAUtils.encryptByPublicKey(mes.getBytes(), publishKey);
		return Base64.getEncoder().encodeToString(encryptedData);
	}
	
	/**
	 * 私钥解密
	 * @param encryptedDate
	 * @return
	 * @throws Exception
	 */
	public static String decryptByPrivateKey(String encryptedDate) throws Exception {
		return decryptByPrivateKey(encryptedDate, "私钥内容");
	}
	
	/**
	 * 公钥加密
	 * @param mes
	 * @return
	 * @throws Exception
	 */
	public static String encryptByPublishKey(String mes) throws Exception {
		return encryptByPublishKey(mes, "公钥内容");
	}
}

欢迎留言讨论。