Java 实现RSA加密、解密、签名、验签

素颜马尾好姑娘i 2023-10-07 11:32 55阅读 0赞

import java.io.ByteArrayOutputStream;
    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.spec.PKCS8EncodedKeySpec;
    import java.security.spec.X509EncodedKeySpec;
    import javax.crypto.Cipher;
    import org.apache.commons.codec.binary.Base64;
    
    public class TestRSA {
        
    
        /**
         * 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;
    
        /**
         * 获取密钥对
         * 
         * @return 密钥对
         */
        public static KeyPair getKeyPair() throws Exception {
        
            KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
            generator.initialize(1024);
            return generator.generateKeyPair();
        }
    
        /**
         * 获取私钥
         * 
         * @param privateKey 私钥字符串
         * @return
         */
        public static PrivateKey getPrivateKey(String privateKey) throws Exception {
        
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
            return keyFactory.generatePrivate(keySpec);
        }
    
        /**
         * 获取公钥
         * 
         * @param publicKey 公钥字符串
         * @return
         */
        public static PublicKey getPublicKey(String publicKey) throws Exception {
        
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
            return keyFactory.generatePublic(keySpec);
        }
        
        /**
         * RSA加密
         * 
         * @param data 待加密数据
         * @param publicKey 公钥
         * @return
         */
        public static String encrypt(String data, PublicKey publicKey) throws Exception {
        
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            int inputLen = data.getBytes().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.getBytes(), offset, MAX_ENCRYPT_BLOCK);
                } else {
        
                    cache = cipher.doFinal(data.getBytes(), offset, inputLen - offset);
                }
                out.write(cache, 0, cache.length);
                i++;
                offset = i * MAX_ENCRYPT_BLOCK;
            }
            byte[] encryptedData = out.toByteArray();
            out.close();
            // 获取加密内容使用base64进行编码,并以UTF-8为标准转化成字符串
            // 加密后的字符串
            return new String(Base64.encodeBase64String(encryptedData));
        }
    
        /**
         * RSA解密
         * 
         * @param data 待解密数据
         * @param privateKey 私钥
         * @return
         */
        public static String decrypt(String data, PrivateKey privateKey) throws Exception {
        
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] dataBytes = Base64.decodeBase64(data);
            int inputLen = dataBytes.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(dataBytes, offset, MAX_DECRYPT_BLOCK);
                } else {
        
                    cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
                }
                out.write(cache, 0, cache.length);
                i++;
                offset = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            // 解密后的内容 
            return new String(decryptedData, "UTF-8");
        }
    
        /**
         * 签名
         * 
         * @param data 待签名数据
         * @param privateKey 私钥
         * @return 签名
         */
        public static String sign(String data, PrivateKey privateKey) throws Exception {
        
            byte[] keyBytes = privateKey.getEncoded();
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey key = keyFactory.generatePrivate(keySpec);
            Signature signature = Signature.getInstance("MD5withRSA");
            signature.initSign(key);
            signature.update(data.getBytes());
            return new String(Base64.encodeBase64(signature.sign()));
        }
    
        /**
         * 验签
         * 
         * @param srcData 原始字符串
         * @param publicKey 公钥
         * @param sign 签名
         * @return 是否验签通过
         */
        public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {
        
            byte[] keyBytes = publicKey.getEncoded();
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PublicKey key = keyFactory.generatePublic(keySpec);
            Signature signature = Signature.getInstance("MD5withRSA");
            signature.initVerify(key);
            signature.update(srcData.getBytes());
            return signature.verify(Base64.decodeBase64(sign.getBytes()));
        }
    
        public static void main(String[] args) {
        
            try {
        
                // 生成密钥对
                KeyPair keyPair = getKeyPair();
                String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
                String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
                System.out.println("私钥:" + privateKey);
                System.out.println("公钥:" + publicKey);
                // RSA加密
                String data = "待加密的文字内容";
                String encryptData = encrypt(data, getPublicKey(publicKey));
                System.out.println("加密后内容:" + encryptData);
                // RSA解密
                String decryptData = decrypt(encryptData, getPrivateKey(privateKey));
                System.out.println("解密后内容:" + decryptData);
                
                // RSA签名
                String sign = sign(data, getPrivateKey(privateKey));
                // RSA验签
                boolean result = verify(data, getPublicKey(publicKey), sign);
                System.out.print("验签结果:" + result);
            } catch (Exception e) {
        
                e.printStackTrace();
                System.out.print("加解密异常");
            }
        }
    }