import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.util.Base64;

public class AESEncryption {
    // 密鑰長(zhǎng)度必須為 16/24/32 字節(jié)
    private static final String AES_ALGORITHM = "AES";
    private static final String AES_MODE = "AES/ECB/PKCS5Padding";

    /**
     * 加密方法
     * @param data 明文數(shù)據(jù)（如JSON格式的交通記錄）
     * @param key 密鑰（16字節(jié)）
     * @return Base64編碼的密文
     */
    public static String encrypt(String data, String key) throws Exception {
        Key secretKey = new SecretKeySpec(key.getBytes(), AES_ALGORITHM);
        Cipher cipher = Cipher.getInstance(AES_MODE);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] encryptedBytes = cipher.doFinal(data.getBytes());
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }

    /**
     * 解密方法
     * @param encryptedData Base64編碼的密文
     * @param key 密鑰（需與加密時(shí)一致）
     * @return 明文數(shù)據(jù)
     */
    public static String decrypt(String encryptedData, String key) throws Exception {
        Key secretKey = new SecretKeySpec(key.getBytes(), AES_ALGORITHM);
        Cipher cipher = Cipher.getInstance(AES_MODE);
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(encryptedData));
        return new String(decryptedBytes);
    }

    // 測(cè)試用例
    public static void main(String[] args) throws Exception {
        String sensitiveData = "{\"plate\": \"粵A12345\", \"location\": {\"lat\": 23.1234, \"lng\": 113.5678}, \"time\": \"2024-03-20T08:30:00\"}";
        String secretKey = "1234567890123456"; // 16字節(jié)密鑰

        String encrypted = encrypt(sensitiveData, secretKey);
        System.out.println("加密后: " + encrypted);

        String decrypted = decrypt(encrypted, secretKey);
        System.out.println("解密后: " + decrypted);
    }
}

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class RSAEncryption {
    private static final String RSA_ALGORITHM = "RSA";

    /**
     * 生成RSA密鑰對(duì)
     */
    public static KeyPair generateKeyPair() throws Exception {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance(RSA_ALGORITHM);
        keyGen.initialize(2048); // 密鑰長(zhǎng)度
        return keyGen.generateKeyPair();
    }

    /**
     * 公鑰加密
     * @param data 待加密的AES密鑰
     * @param publicKey 公鑰
     * @return Base64編碼的密文
     */
    public static String encryptWithPublicKey(String data, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return Base64.getEncoder().encodeToString(cipher.doFinal(data.getBytes()));
    }

    /**
     * 私鑰解密
     * @param encryptedData Base64編碼的密文
     * @param privateKey 私鑰
     * @return 明文AES密鑰
     */
    public static String decryptWithPrivateKey(String encryptedData, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return new String(cipher.doFinal(Base64.getDecoder().decode(encryptedData)));
    }

    // 測(cè)試用例
    public static void main(String[] args) throws Exception {
        KeyPair keyPair = generateKeyPair();
        String aesKey = "1234567890123456"; // 假設(shè)這是AES密鑰

        String encryptedAesKey = encryptWithPublicKey(aesKey, keyPair.getPublic());
        System.out.println("RSA加密后的AES密鑰: " + encryptedAesKey);

        String decryptedAesKey = decryptWithPrivateKey(encryptedAesKey, keyPair.getPrivate());
        System.out.println("RSA解密后的AES密鑰: " + decryptedAesKey);
    }
}

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Random;

public class DataAnonymizer {
    /**
     * 哈希車牌號(hào)（SHA-256）
     * @param plate 車牌號(hào)
     * @return 哈希值（16進(jìn)制前8位）
     */
    public static String anonymizePlate(String plate) {
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            byte[] hashBytes = digest.digest(plate.getBytes());
            StringBuilder hex = new StringBuilder();
            for (byte b : hashBytes) {
                hex.append(String.format("%02x", b));
            }
            return hex.toString().substring(0, 8); // 取前8位
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("SHA-256 not supported", e);
        }
    }

    /**
     * 模糊時(shí)間戳到15分鐘粒度
     * @param timestamp 原始時(shí)間（ISO 8601格式）
     * @return 模糊后的時(shí)間
     */
    public static String anonymizeTimestamp(String timestamp) {
        LocalDateTime dateTime = LocalDateTime.parse(timestamp);
        int minutes = dateTime.getMinute();
        // 將分鐘數(shù)向下取整到最近的15的倍數(shù)
        int roundedMinutes = (minutes / 15) * 15;
        return dateTime.withMinute(roundedMinutes).format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
    }

    /**
     * 擾動(dòng)坐標(biāo)（±500米）
     * @param lat 原始緯度
     * @param lng 原始經(jīng)度
     * @return 擾動(dòng)后的坐標(biāo)（保留4位小數(shù)）
     */
    public static String[] anonymizeLocation(double lat, double lng) {
        Random random = new Random();
        double deltaLat = random.nextDouble() * 0.0005 - 0.00025; // ±0.00025° ≈ 28米
        double deltaLng = random.nextDouble() * 0.0005 - 0.00025;
        return new String[]{
            String.format("%.4f", lat + deltaLat),
            String.format("%.4f", lng + deltaLng)
        };
    }

    // 測(cè)試用例
    public static void main(String[] args) {
        String plate = "粵A12345";
        String timestamp = "2024-03-20T08:30:00";
        double lat = 23.1234, lng = 113.5678;

        System.out.println("原始車牌: " + plate);
        System.out.println("匿名化后: " + anonymizePlate(plate));

        System.out.println("原始時(shí)間: " + timestamp);
        System.out.println("匿名化后: " + anonymizeTimestamp(timestamp));

        String[] location = anonymizeLocation(lat, lng);
        System.out.printf("原始坐標(biāo): %.4f, %.4f%n", lat, lng);
        System.out.printf("匿名化后: %s, %s%n", location[0], location[1]);
    }
}

[原始數(shù)據(jù)]
   ↓ 加密
[加密數(shù)據(jù)] 
   ↓ HTTPS傳輸
[服務(wù)端接收]
   ↓ 解密
[解密數(shù)據(jù)]
   ↓ 匿名化處理
[匿名數(shù)據(jù)]
   ↓ 存儲(chǔ)/分析

import java.io.FileWriter;
import java.io.IOException;
import java.time.LocalDateTime;

public class AuditLogger {
    private static final String LOG_FILE = "security_audit.log";

    /**
     * 記錄操作日志
     * @param action 操作類型（加密/解密/匿名化）
     * @param status 狀態(tài)（成功/失敗）
     * @param detail 附加信息
     */
    public static void log(String action, String status, String detail) {
        try (FileWriter writer = new FileWriter(LOG_FILE, true)) {
            String timestamp = LocalDateTime.now().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
            String logEntry = String.format("[%s] [ACTION=%s] [STATUS=%s] %s%n",
                    timestamp, action, status, detail);
            writer.write(logEntry);
        } catch (IOException e) {
            System.err.println("日志記錄失敗: " + e.getMessage());
        }
    }

    // 示例調(diào)用
    public static void main(String[] args) {
        log("ENCRYPT", "SUCCESS", "AES加密完成，密文長(zhǎng)度: 128");
        log("ANONYMIZE", "WARNING", "車牌號(hào)哈希沖突，已重新計(jì)算");
    }
}

// 偽代碼示意
HomomorphicEncryptedData encryptedData = encryptWithHomomorphic(data);
AnalysisResult result = performAnalysis(encryptedData); // 密文分析
String clearResult = decrypt(result); // 最終結(jié)果解密

// 偽代碼示意
Blockchain.blockchain.add(
    new AuditEvent(
        "2024-03-20T09:00:00",
        "admin",
        "ANONYMIZE",
        "成功匿名化10萬條交通數(shù)據(jù)"
    )
);