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需求背景

应用程序开发的时候，往往会存在一些敏感的配置属性

• 数据库账号、密码
• 第三方服务账号密码
• 内置加密密码
• 其他的敏感配置

对于安全性要求比较高的公司，往往不允许敏感配置以明文的方式出现。
通常做法是对这些敏感配置进行加密，然后在使用的地方进行解密。但是有一些第三方的配置可能未提供解密注入点如数据库密码，这时要实现起来就比较麻烦。有没有比较方便的方法可以自动识别并解密。
本次主要针对这个问题，解决敏感配置的加密问题

实现思路

• 使用已有的第三方包：如jasypt-spring-boot
  
  • 这是一个针对SpringBoot项目配置进行加解密的包，可以在项目里通过引入依赖来实现。具体使用方式自行搜索
• 参考官方文档利用官方提供的扩展点自己实现
  • 实现EnvironmentPostProcessor
    • EnvironmentPostProcessor在配置文件解析后，bean创建前调用
  • 实现BeanFactoryPostProcessor（优先考虑）
    • BeanFactoryPostProcessor在配置文件解析后，bean创建前调用
    • 实现方式同EnvironmentPostProcessor基本一致，注入时机更靠后。

通过实现EnvironmentPostProcessor方式解决

实现EnvironmentPostProcessor可自定义环境配置处理逻辑。实现示例如下

    @Overridepublic void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {MutablePropertySources mutablePropertySources = environment.getPropertySources();for (PropertySource<?> propertySource : mutablePropertySources) {if (propertySource instanceof OriginTrackedMapPropertySource) {mutablePropertySources.replace(propertySource.getName(),// 实现一个包装类，动态判断new PropertySourceWrapper(propertySource, initSimpleEncryptor("reduck-project"), new EncryptionWrapperDetector("$ENC{", "}")));}}}

EnvironmentPostProcessor 也可以自动扩展配置文件，如果有些项目自己在这个扩展点实现了自己的配置加载逻辑，可能就需要考虑顺序问题。这里比较推荐实现BeanFactoryPostProcessor，他在EnvironmentPostProcessor相关实例处理后调用，且在Bean创建前。可以更好满足需求。

通过实现BeanFactoryPostProcessor解决

• 实现EncryptionBeanPostProcessor
  • 一般OriginTrackedMapPropertySource是我们自定义的配置加载实例，通过一个包装类替换原先的实例

@RequiredArgsConstructor
public class EncryptionBeanPostProcessor implements BeanFactoryPostProcessor, Ordered {private final ConfigurableEnvironment environment;@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {MutablePropertySources mutablePropertySources = environment.getPropertySources();String secretKey = environment.getProperty("configuration.crypto.secret-key");if(secretKey ==  null) {return;}for (PropertySource<?> propertySource : mutablePropertySources) {if (propertySource instanceof OriginTrackedMapPropertySource) {mutablePropertySources.replace(propertySource.getName(),new PropertySourceWrapper(propertySource, new AesEncryptor(PrivateKeyFinder.getSecretKey(secretKey)), new EncryptionWrapperDetector("$ENC{", "}")));}}}@Overridepublic int getOrder() {return Ordered.LOWEST_PRECEDENCE - 100;}
}

• 定义一个 PropertySource包装类
  • PropertySource只有一个方法 public Object getProperty(String name)，只需要实现这个方法，如果是加密配置就解密

public class PropertySourceWrapper<T> extends PropertySource<T> {private final String prefix = "$ENC{";private final String suffix = "}";private final Encryptor encryptor;private final PropertySource<T> originalPropertySource;private final EncryptionWrapperDetector detector;public PropertySourceWrapper(PropertySource<T> originalPropertySource, Encryptor encryptor, EncryptionWrapperDetector detector) {super(originalPropertySource.getName(), originalPropertySource.getSource());this.originalPropertySource = originalPropertySource;this.encryptor = encryptor;this.detector = detector;}@Overridepublic Object getProperty(String name) {if (originalPropertySource.containsProperty(name)) {Object value = originalPropertySource.getProperty(name);if (value != null) {String property = value.toString();if (detector.detected(property)) {return encryptor.decrypt(detector.unWrapper(property));}}}return originalPropertySource.getProperty(name);}
}

• 定义一个加解密帮助类EncryptionWrapperDetector
  • 根据前后缀判断是否是加密属性
  • 对加密属性进行包装
  • 对加密属性去除包装

public class EncryptionWrapperDetector {private final String prefix;private final String suffix;public EncryptionWrapperDetector(String prefix, String suffix) {this.prefix = prefix;this.suffix = suffix;}public boolean detected(String property) {return property != null && property.startsWith(prefix) && property.endsWith(suffix);}public String wrapper(String property) {return prefix + property + suffix;}public String unWrapper(String property) {return property.substring(prefix.length(), property.length() - suffix.length());}
}

• 定义一个加解密类
  • 对配置文件进行加密
  • 对配置问价进行解密

public class AesEncryptor implements Encryptor {private final byte[] secretKey;private final byte[] iv = new byte[16];public AesEncryptor(byte[] secretKey) {this.secretKey = secretKey;System.arraycopy(secretKey, 0, iv, 0, 16);}@Overridepublic String encrypt(String message) {return Base64.getEncoder().encodeToString(_AesUtils.encrypt(secretKey, iv, message.getBytes()));}@Overridepublic String decrypt(String message) {return new String(_AesUtils.decrypt(secretKey, iv, Base64.getDecoder().decode(message)));}
}

• 密钥加密存储
  • 采用非对称加密方式对密钥进行加密，用公钥加密后的密钥可以直接写在配置文件中
  • 在进行解密的时候先通过内置的私钥解密获取原始加密密钥
  • 注意细节
    • 私钥存储的时候可以再进行一次加密
    • 私钥可放在META-INF路径下，通过Classloader获取

public class PrivateKeyFinder {private static final String PRIVATE_KEY_RESOURCE_LOCATION = "META-INF/configuration.crypto.private-key";private static final String PUBLIC_KEY_RESOURCE_LOCATION = "META-INF/configuration.crypto.public-key";private final byte[] keyInfo = new byte[]{(byte) 0xD0, (byte) 0x20, (byte) 0xDA, (byte) 0x92, (byte) 0xC8, (byte) 0x0B, (byte) 0x6D, (byte) 0x57,(byte) 0x48, (byte) 0x7B, (byte) 0x15, (byte) 0x3A, (byte) 0x44, (byte) 0xA0, (byte) 0x98, (byte) 0xC2,(byte) 0xF1, (byte) 0x6F, (byte) 0xB6, (byte) 0x09, (byte) 0x2F, (byte) 0x6D, (byte) 0x69, (byte) 0xFB,(byte) 0x2D, (byte) 0x02, (byte) 0x00, (byte) 0xCB, (byte) 0xBE, (byte) 0x48, (byte) 0xDD, (byte) 0xD5,(byte) 0x90, (byte) 0xC2, (byte) 0x95, (byte) 0x98, (byte) 0x60, (byte) 0x59, (byte) 0x24, (byte) 0xE2,(byte) 0xB7, (byte) 0x84, (byte) 0x12, (byte) 0x5D, (byte) 0xB9, (byte) 0xC1, (byte) 0x19, (byte) 0xFF,(byte) 0x4F, (byte) 0x01, (byte) 0xB9, (byte) 0xC5, (byte) 0xD8, (byte) 0xD2, (byte) 0x99, (byte) 0xEE,(byte) 0xAA, (byte) 0x0D, (byte) 0x59, (byte) 0xF8, (byte) 0x37, (byte) 0x49, (byte) 0x91, (byte) 0xAB};static byte[] getSecretKey(String encKey) {byte[] key = loadPrivateKey();return RsaUtils.decrypt(Base64.getDecoder().decode(encKey), new PrivateKeyFinder().decrypt(Base64.getDecoder().decode(key)));}static String generateSecretKey() {return Base64.getEncoder().encodeToString(RsaUtils.encrypt(new SecureRandom().generateSeed(16), Base64.getDecoder().decode(loadPublicKey())));}static String generateSecretKeyWith256() {return Base64.getEncoder().encodeToString(RsaUtils.encrypt(new SecureRandom().generateSeed(32), Base64.getDecoder().decode(loadPublicKey())));}@SneakyThrowsstatic byte[] loadPrivateKey() {return loadResource(PRIVATE_KEY_RESOURCE_LOCATION);}@SneakyThrowsstatic byte[] loadPublicKey() {return loadResource(PUBLIC_KEY_RESOURCE_LOCATION);}@SneakyThrowsprivate static byte[] loadResource(String location) {// just lookup from current jar  pathClassLoader classLoader = new URLClassLoader(new URL[]{PrivateKeyFinder.class.getProtectionDomain().getCodeSource().getLocation()}, null);
//        classLoader = PrivateKeyFinder.class.getClassLoader();Enumeration<URL> enumeration = classLoader.getResources(location);// should only find onewhile (enumeration.hasMoreElements()) {URL url = enumeration.nextElement();UrlResource resource = new UrlResource(url);return FileCopyUtils.copyToByteArray(resource.getInputStream());}return null;}private final String CIPHER_ALGORITHM = "AES/CBC/NoPadding";private final String KEY_TYPE = "AES";@SneakyThrowspublic byte[] encrypt(byte[] data) {byte[] key = new byte[32];byte[] iv = new byte[16];System.arraycopy(keyInfo, 0, key, 0, 32);System.arraycopy(keyInfo, 32, iv, 0, 16);Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, KEY_TYPE), new IvParameterSpec(iv));return cipher.doFinal(data);}@SneakyThrowspublic byte[] decrypt(byte[] data) {byte[] key = new byte[32];byte[] iv = new byte[16];System.arraycopy(keyInfo, 0, key, 0, 32);System.arraycopy(keyInfo, 32, iv, 0, 16);Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, KEY_TYPE), new IvParameterSpec(iv));return cipher.doFinal(data);}
}

综上既可以实现敏感配置文件的加解密，同时可以保障加密密钥的安全传入