非对称加密算法RSA工具

非对称加密算法RSA工具

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

import org.bouncycastle.util.encoders.Base64;

public class RSAUtil {

	/**
	 * RSA算法
	 */
	private static final String KEY_ALGORITHM = "RSA";
	/**
	 * 数字签名
	 */
	private static final String SIGNATURE_ALGORITHM = "MD5withRSA";

	/**
	 * 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;

	public static String[] createKeys() {
		try {
			KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
			keyPairGen.initialize(1024);
			KeyPair keyPair = keyPairGen.generateKeyPair();
			// 公钥
			RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
			// 私钥
			RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
			String[] res = new String[2];
			res[0] = byteArrayToBase64Str(publicKey.getEncoded());
			res[1] = byteArrayToBase64Str(privateKey.getEncoded());
			return res;
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return null;
	}

	private static byte[] base64StrToByteArray(String data) {
		return Base64.decode(data.getBytes());
	}

	private static String byteArrayToBase64Str(byte[] data) {
		return Base64.toBase64String(data);
	}

	/**
	 * 数字签名
	 * 
	 * @param data       要签名的密文
	 * @param privateKey 私钥
	 * @return 返回签名信息
	 */
	public static String RSASign(String data, String privateKey) {
		try {
			// 解密由base64编码的私钥
			byte[] keyBytes = base64StrToByteArray(privateKey);
			// 构造PKCS8EncodedKeySpec对象
			PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
			// KEY_ALGORITHM 指定的加密算法
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
			// 取私钥匙对象
			PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
			// 用私钥对信息生成数字签名
			Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
			signature.initSign(priKey);
			signature.update(base64StrToByteArray(data));
			return byteArrayToBase64Str(signature.sign());
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (SignatureException e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 验证签名
	 * 
	 * @param data      要验证的密文
	 * @param publicKey 公钥
	 * @param sign      签名信息
	 * @return 返回验证成功状态
	 */
	public static boolean RSAVerify(String data, String publicKey, String sign) {
		try {
			// 解密由base64编码的公钥
			byte[] keyBytes = base64StrToByteArray(publicKey);
			// 构造X509EncodedKeySpec对象
			X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
			// KEY_ALGORITHM 指定的加密算法
			Signature signature;
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
			// 取公钥匙对象
			PublicKey pubKey = keyFactory.generatePublic(keySpec);
			signature = Signature.getInstance(SIGNATURE_ALGORITHM);
			signature.initVerify(pubKey);
			signature.update(base64StrToByteArray(data));
			// 验证签名是否正常
			return signature.verify(base64StrToByteArray(sign));
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (SignatureException e) {
			e.printStackTrace();
		}
		return false;
	}

	/**
	 * 私钥解密
	 * 
	 * @param data 要解密的字符串
	 * @param key  私钥
	 * @return 返回解密后的字符串
	 */
	public static String RSADecryptByPrivateKey(String data, String key) {
		try {
			// 对密钥解密
			byte[] keyBytes = base64StrToByteArray(key);
			// 取得私钥
			PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
			Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
			// 对数据解密
			Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
			cipher.init(Cipher.DECRYPT_MODE, privateKey);

			byte[] encryptedData = base64StrToByteArray(data);
			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 new String(decryptedData);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 公钥解密
	 * 
	 * @param data 要解密的数据
	 * @param key  公钥
	 * @return 返回解密后的数据
	 */
	public static String RSADecryptByPublicKey(String data, String key) {
		try {
			// 对密钥解密
			byte[] keyBytes = base64StrToByteArray(key);
			// 取得公钥
			X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
			Key publicKey = keyFactory.generatePublic(x509KeySpec);
			// 对数据解密
			Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
			cipher.init(Cipher.DECRYPT_MODE, publicKey);

			byte[] encryptedData = base64StrToByteArray(data);
			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 new String(decryptedData);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 公钥加密
	 * 
	 * @param data 要加密的数据
	 * @param key  公钥
	 * @return 返回加密的数据
	 */
	public static String RSAEncryptByPublicKey(String data, String key) {
		try {
			// 对公钥解密
			byte[] keyBytes = base64StrToByteArray(key);
			// 取得公钥
			X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
			Key publicKey = keyFactory.generatePublic(x509KeySpec);
			// 对数据加密
			Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
			cipher.init(Cipher.ENCRYPT_MODE, publicKey);

			byte[] decryptedData = data.getBytes();
			int inputLen = decryptedData.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_ENCRYPT_BLOCK) {
					cache = cipher.doFinal(decryptedData, offSet, MAX_ENCRYPT_BLOCK);
				} else {
					cache = cipher.doFinal(decryptedData, offSet, inputLen - offSet);
				}
				out.write(cache, 0, cache.length);
				i++;
				offSet = i * MAX_ENCRYPT_BLOCK;
			}
			byte[] encryptedData = out.toByteArray();
			out.close();
			return byteArrayToBase64Str(encryptedData);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 私钥加密
	 * 
	 * @param data 要加密的数据
	 * @param key  私钥
	 * @return 返回加密后的数据
	 */
	public static String RSAEncryptByPrivateKey(String data, String key) {
		try {
			// 对密钥解密
			byte[] keyBytes = base64StrToByteArray(key);
			// 取得私钥
			PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
			Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
			// 对数据加密
			Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
			cipher.init(Cipher.ENCRYPT_MODE, privateKey);

			byte[] decryptedData = data.getBytes();
			int inputLen = decryptedData.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_ENCRYPT_BLOCK) {
					cache = cipher.doFinal(decryptedData, offSet, MAX_ENCRYPT_BLOCK);
				} else {
					cache = cipher.doFinal(decryptedData, offSet, inputLen - offSet);
				}
				out.write(cache, 0, cache.length);
				i++;
				offSet = i * MAX_ENCRYPT_BLOCK;
			}
			byte[] encryptedData = out.toByteArray();
			out.close();
			return byteArrayToBase64Str(encryptedData);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}
}