Spring微服务读取varbinary存储的RSA密钥报InvalidKeySpecException

相关实现代码 #

@Autowired
private UsuarioRepository usuarioRepository;

public String prueba(String data) {
    
    generateKeys(data); 
    
    byte[] text=encryptPrivate("texto de prueba lala",data);
    String texto=decryptPublic(text,data);
    
    return texto;
}

public String generateKeys(String username) {

    KeyPairGenerator keyPairGenerator = null;
    try {
        keyPairGenerator = KeyPairGenerator.getInstance("RSA");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }

    keyPairGenerator.initialize(512); // 64的倍数，取值范围512 ~ 65536

    KeyPair keyPair = keyPairGenerator.generateKeyPair();

    RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
    System.out.println("Private: " + rsaPrivateKey);

    RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
    System.out.println("Public: " + rsaPublicKey);
    
    byte[] publicKeyBytes = keyPair.getPublic().getEncoded();
    byte[] privateKeyBytes = keyPair.getPrivate().getEncoded();
    System.out.println("Encoded: " + publicKeyBytes);
    
    usuarioRepository.add(publicKeyBytes, privateKeyBytes, username);

    return "ok";
}

public byte[] encryptPrivate(String data, String username) {
    
    // 从数据库读取密钥
    byte[] keyBytes = getPrKey(username);
    EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
   
    try {
         KeyFactory kf = KeyFactory.getInstance("RSA"); 
         RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) kf.generatePrivate(spec);
         Cipher cipher = Cipher.getInstance("RSA");
         cipher.init(Cipher.ENCRYPT_MODE, rsaPrivateKey);
         byte[] cipherText = cipher.doFinal(data.getBytes());
         
         return cipherText;
         
    } catch (InvalidKeySpecException | NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
        e.printStackTrace();
    }
    return null;
}

public String decryptPublic(byte[] data, String username) {

    byte[] keyBytes = getPuKey(username);
    X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
    try {
         KeyFactory kf = KeyFactory.getInstance("RSA"); 
         RSAPublicKey rsaPublicKey = (RSAPublicKey) kf.generatePublic(spec);
         Cipher cipher = Cipher.getInstance("RSA");
         cipher.init(Cipher.DECRYPT_MODE, rsaPublicKey); 
         byte[] plainText = cipher.doFinal(data);
         return new String(plainText);
         
    } catch (InvalidKeySpecException | NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
        e.printStackTrace();
    }
    return "fail";      
            
}

问题描述 #

异常触发代码行：
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) kf.generatePrivate(spec);
密钥存储在数据库varbinary类型字段，运行时抛出如下异常：

java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : DerValue.getBigIntegerInternal, not expected 48
at java.base/sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(RSAKeyFactory.java:252)
...
Caused by: java.security.InvalidKeyException: IOException : DerValue.getBigIntegerInternal, not expected 48
at java.base/sun.security.pkcs.PKCS8Key.decode(PKCS8Key.java:133)
...
java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException: algid parse error, not a sequence
at java.base/sun.security.rsa.RSAKeyFactory.engineGeneratePublic(RSAKeyFactory.java:240)
...
Caused by: java.security.InvalidKeyException: IOException: algid parse error, not a sequence
at java.base/sun.security.x509.X509Key.decode(X509Key.java:397)

排查步骤 #

• 校验密钥字节一致性：存储密钥前打印公/私钥字节数组的长度、前10位字节值，读取后再打印相同参数，对比是否完全一致。该类异常90%以上都是因为读写过程中字节被篡改导致。
• 校验数据库字段长度：512位RSA的PKCS8编码私钥长度约300字节，X509公钥约100字节，若varbinary字段长度设置过小会导致存储时字节被截断，无法正常解析。
• 校验编码转换逻辑：排查是否存在将密钥字节数组通过new String()、字符串转字节等操作处理的逻辑，字符集编码会破坏原始密钥字节结构。

解决方案 #

1. 修正持久层映射逻辑：确保数据库varbinary字段对应的实体类属性直接声明为byte[]类型，不要通过String类型中转，避免框架自动做字符集转换破坏字节结构。
2. 调整数据库字段长度：将存储公钥、私钥的varbinary字段长度调整为至少2048，兼容后续升级到2048位及以上长度的RSA密钥。
3. 兼容方案：如果存在跨系统读取密钥的需求，可以将密钥字节数组先通过Base64编码为字符串，存储在varchar字段中，读取后先做Base64解码再生成密钥对象，示例逻辑如下：

// 存储前编码
String pubKeyStr = Base64.getEncoder().encodeToString(publicKeyBytes);
String prKeyStr = Base64.getEncoder().encodeToString(privateKeyBytes);
// 读取后解码
byte[] pubKeyBytes = Base64.getDecoder().decode(pubKeyStrFromDb);
byte[] prKeyBytes = Base64.getDecoder().decode(prKeyStrFromDb);

内容的提问来源于stack exchange，提问作者Rafael Muñoz