335 lines
12 KiB
Java
335 lines
12 KiB
Java
package com.secure.device;
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import android.content.Context;
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import android.security.keystore.KeyGenParameterSpec;
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import android.security.keystore.KeyProperties;
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import java.security.KeyPair;
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import java.security.KeyPairGenerator;
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import java.security.KeyStore;
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import java.security.PrivateKey;
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import java.security.PublicKey;
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import java.security.Signature;
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import java.util.Base64;
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import javax.crypto.Cipher;
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import javax.crypto.KeyGenerator;
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import javax.crypto.SecretKey;
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import javax.crypto.spec.GCMParameterSpec;
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/**
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* 设备端安全模块（Android）
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*
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* 核心设计：
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* - TEE 密钥对（RSA-2048）：私钥不可导出，用于解密服务端下发数据 + 签名
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* - 每次拍照生成随机 DEK（AES-256）：用后即弃
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* - DEK 明文通过 HTTPS 传给服务端，服务端用 UK 加密后存储
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*
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* 安全边界：
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* - 私钥永不出 TEE
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* - SN 仅做身份标识，不参与加密
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* - 恢复出厂 → 密钥销毁 → 新密钥对 → 用户短信验证恢复
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*/
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public class DeviceCrypto {
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// ==================== 常量 ====================
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private static final String KEYSTORE_PROVIDER = "AndroidKeyStore";
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private static final String KEY_ALIAS = "device_tee_key";
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private static final String KEY_ALGO = KeyProperties.KEY_ALGORITHM_RSA;
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private static final int RSA_KEY_SIZE = 2048;
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private static final String SIGN_ALGO = "SHA256withRSA";
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private static final String RSA_TRANSFORM = "RSA/ECB/OAEPWithSHA-256AndMGF1Padding";
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private static final int AES_KEY_SIZE = 256;
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private static final int GCM_IV_LENGTH = 12;
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private static final int GCM_TAG_LENGTH = 128;
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private final Context context;
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private KeyStore keyStore;
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// ==================== 构造与初始化 ====================
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public DeviceCrypto(Context context) {
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this.context = context;
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initKeyStore();
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}
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/**
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* 初始化 AndroidKeyStore，如不存在密钥对则生成
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*
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* 安全属性：
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* - PURPOSE_DECRYPT + PURPOSE_SIGN（私钥只用于解密下发数据 + 签名）
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* - StrongBox 优先（硬件安全模块）
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* - 不可导出
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*/
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private void initKeyStore() {
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try {
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keyStore = KeyStore.getInstance(KEYSTORE_PROVIDER);
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keyStore.load(null);
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if (!keyStore.containsAlias(KEY_ALIAS)) {
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generateTeeKeyPair();
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}
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} catch (Exception e) {
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throw new RuntimeException("KeyStore init failed", e);
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}
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}
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/**
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* 在 TEE / StrongBox 中生成 RSA-2048 密钥对
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*/
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private void generateTeeKeyPair() {
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try {
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KeyPairGenerator kpg = KeyPairGenerator.getInstance(
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KEY_ALGO, KEYSTORE_PROVIDER);
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KeyGenParameterSpec spec = new KeyGenParameterSpec.Builder(
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KEY_ALIAS,
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KeyProperties.PURPOSE_DECRYPT |
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KeyProperties.PURPOSE_SIGN
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)
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.setKeySize(RSA_KEY_SIZE)
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.setDigests(KeyProperties.DIGEST_SHA256)
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.setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_RSA_OAEP)
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.setSignaturePaddings(KeyProperties.SIGNATURE_PADDING_RSA_PKCS1)
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.setUserAuthenticationRequired(false) // 无登录体系
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.setIsStrongBoxBacked(true) // 优先 StrongBox
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.build();
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kpg.initialize(spec);
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kpg.generateKeyPair();
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} catch (Exception e) {
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throw new RuntimeException("TEE key gen failed", e);
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}
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}
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// ==================== 公钥导出 ====================
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/**
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* 获取设备公钥（Base64 编码）
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* 公钥可导出，用于：
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* - 上传服务端存储
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* - 服务端加密下发数据
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*/
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public String getPublicKeyBase64() {
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try {
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KeyStore.PrivateKeyEntry entry =
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(KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
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PublicKey publicKey = entry.getCertificate().getPublicKey();
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return Base64.getEncoder().encodeToString(publicKey.getEncoded());
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} catch (Exception e) {
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throw new RuntimeException("Get public key failed", e);
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}
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}
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/**
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* 获取设备 SN
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* 实际实现：android.os.Build.getSerial()
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*/
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public String getDeviceSN() {
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// return android.os.Build.getSerial();
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return "SN-DEMO-001";
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}
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// ==================== 数据信封加密 ====================
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/**
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* 加密敏感数据（如照片）
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*
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* 流程：
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* 1. 生成随机 AES-256 DEK
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* 2. 生成随机 12 字节 IV
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* 3. AES-256-GCM 加密数据
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* 4. 返回密文 + IV + 明文DEK（DEK 由服务端用 UK 加密存储）
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*
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* @return EncryptedPayload
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*/
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public EncryptedPayload encryptData(byte[] plaintext) {
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try {
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// 1. 随机 DEK
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KeyGenerator kg = KeyGenerator.getInstance("AES");
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kg.init(AES_KEY_SIZE);
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SecretKey dek = kg.generateKey();
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// 2. 随机 IV
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byte[] iv = new byte[GCM_IV_LENGTH];
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java.security.SecureRandom random = new java.security.SecureRandom();
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random.nextBytes(iv);
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// 3. AES-256-GCM 加密
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Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
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GCMParameterSpec gcmSpec = new GCMParameterSpec(GCM_TAG_LENGTH, iv);
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cipher.init(Cipher.ENCRYPT_MODE, dek, gcmSpec);
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byte[] ciphertext = cipher.doFinal(plaintext);
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return new EncryptedPayload(
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Base64.getEncoder().encodeToString(ciphertext),
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Base64.getEncoder().encodeToString(iv),
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Base64.getEncoder().encodeToString(dek.getEncoded())
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);
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} catch (Exception e) {
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throw new RuntimeException("Encrypt failed", e);
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}
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}
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// ==================== 元数据签名 ====================
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/**
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* 对元数据做 RSA 签名（防伪造、防篡改）
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*
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* 签名内容示例："SN-xxx|timestamp|photoId"
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* 服务端用设备公钥验签
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*/
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public String signMetadata(String metadata) {
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try {
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KeyStore.PrivateKeyEntry entry =
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(KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
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PrivateKey privateKey = entry.getPrivateKey();
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Signature sig = Signature.getInstance(SIGN_ALGO);
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sig.initSign(privateKey);
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sig.update(metadata.getBytes("UTF-8"));
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byte[] signature = sig.sign();
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return Base64.getEncoder().encodeToString(signature);
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} catch (Exception e) {
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throw new RuntimeException("Sign failed", e);
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}
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}
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// ==================== 恢复流程 ====================
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/**
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* 恢复出厂后，服务端下发用新公钥加密的 Recovery Token
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* 本方法用 TEE 私钥解密，获取 Token
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*
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* @param encryptedToken 服务端用设备公钥加密的 Token
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* @return 明文 Token（格式：userId|deviceId|timestamp|nonce）
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*/
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public String decryptRecoveryToken(byte[] encryptedToken) {
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try {
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KeyStore.PrivateKeyEntry entry =
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(KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
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PrivateKey privateKey = entry.getPrivateKey();
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Cipher cipher = Cipher.getInstance(RSA_TRANSFORM);
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cipher.init(Cipher.DECRYPT_MODE, privateKey);
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byte[] decrypted = cipher.doFinal(encryptedToken);
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return new String(decrypted, "UTF-8");
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} catch (Exception e) {
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throw new RuntimeException("Decrypt recovery token failed", e);
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}
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}
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/**
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* 解密服务端下发的加密 DEK
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* 恢复流程中，服务端用设备公钥加密每个照片的 DEK
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*
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* @param encryptedDek 加密的 DEK（Base64）
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* @return 明文 DEK 字节
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*/
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public byte[] decryptDek(String encryptedDekBase64) {
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try {
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KeyStore.PrivateKeyEntry entry =
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(KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
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PrivateKey privateKey = entry.getPrivateKey();
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Cipher cipher = Cipher.getInstance(RSA_TRANSFORM);
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cipher.init(Cipher.DECRYPT_MODE, privateKey);
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return cipher.doFinal(Base64.getDecoder().decode(encryptedDekBase64));
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} catch (Exception e) {
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throw new RuntimeException("Decrypt DEK failed", e);
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}
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}
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/**
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* 用解出的 DEK 解密照片
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*/
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public byte[] decryptPhoto(String ciphertextBase64, String ivBase64, byte[] dekBytes) {
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try {
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SecretKey dek = new javax.crypto.spec.SecretKeySpec(dekBytes, "AES");
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byte[] iv = Base64.getDecoder().decode(ivBase64);
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byte[] ciphertext = Base64.getDecoder().decode(ciphertextBase64);
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Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
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GCMParameterSpec spec = new GCMParameterSpec(GCM_TAG_LENGTH, iv);
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cipher.init(Cipher.DECRYPT_MODE, dek, spec);
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return cipher.doFinal(ciphertext);
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} catch (Exception e) {
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throw new RuntimeException("Decrypt photo failed", e);
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}
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}
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// ==================== 数据模型 ====================
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/**
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* 加密后的数据载体
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*/
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public static class EncryptedPayload {
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public final String ciphertextBase64; // AES-GCM 密文
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public final String ivBase64; // GCM IV
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public final String dekBase64; // 明文 DEK（HTTPS 传输给服务端）
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public EncryptedPayload(String ciphertextBase64, String ivBase64, String dekBase64) {
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this.ciphertextBase64 = ciphertextBase64;
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this.ivBase64 = ivBase64;
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this.dekBase64 = dekBase64;
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}
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}
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/**
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* 设备注册请求体
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*/
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public static class DeviceRegisterRequest {
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public String sn;
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public String publicKeyBase64;
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public DeviceRegisterRequest(String sn, String publicKeyBase64) {
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this.sn = sn;
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this.publicKeyBase64 = publicKeyBase64;
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}
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}
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/**
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* 上传加密照片请求体
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*/
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public static class UploadPhotoRequest {
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public String sn;
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public String photoId;
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public String ciphertextBase64;
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public String ivBase64;
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public String dekBase64;
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public String metadataSignature;
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public String metadata;
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public UploadPhotoRequest(String sn, String photoId, String ciphertextBase64,
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String ivBase64, String dekBase64,
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String metadataSignature, String metadata) {
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this.sn = sn;
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this.photoId = photoId;
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this.ciphertextBase64 = ciphertextBase64;
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this.ivBase64 = ivBase64;
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this.dekBase64 = dekBase64;
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this.metadataSignature = metadataSignature;
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this.metadata = metadata;
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}
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}
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/**
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* 恢复请求体（用户已通过短信验证）
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*/
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public static class RecoveryRequest {
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public String sn;
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public String userId;
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public String smsCode;
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public String newPublicKeyBase64;
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public RecoveryRequest(String sn, String userId, String smsCode, String newPublicKeyBase64) {
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this.sn = sn;
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this.userId = userId;
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this.smsCode = smsCode;
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this.newPublicKeyBase64 = newPublicKeyBase64;
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}
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}
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}
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