在 Poco Crypto 中设置加密填充

Question

是否可以在 Poco Crypto 中设置填充以使用 AES128 进行加密？我找不到任何选项。

std::string Crypto::Encrypt(const std::string &input, const std::string &key)
{
    Poco::Crypto::Cipher::ByteVec iv { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
    Poco::Crypto::Cipher::ByteVec key2 {key.begin(), key.end()};

    Poco::Crypto::Cipher::Ptr pCipher = Poco::Crypto::CipherFactory::defaultFactory()
        .createCipher(Poco::Crypto::CipherKey("aes128", key2, iv));

    std::string output = pCipher->encryptString(input);

    return std::move(output);
}

在简单的 OpenSSL 中，我有这个选项：

EVP_CIPHER_CTX *ctx;

EVP_CIPHER_CTX_set_padding(ctx, 0)

Answer 1

默认情况下启用填充。

根据Crypto/include/Poco/Crypto/CryptoTransform.h或https://pocoproject.org/docs/Poco.Crypto.CryptoTransform.html#230中的评论，默认填充加密操作。

...
virtual int setPadding(int padding);
    /// Enables or disables padding. By default encryption operations are padded using standard block 
    /// padding and the padding is checked and removed when decrypting. If the padding parameter is zero then 
    /// no padding is performed, the total amount of data encrypted or decrypted must then be a multiple of 
    /// the block size or an error will occur.
...

如果你想改变填充选项，你应该覆盖 Poco::Crypto::Cipher 中的 createEncryptor()、creatoreDecryptor()，如下所示

class CipherWithPadding : public Poco::Crypto::Cipher
{
public:
    // by default no padding, for more information refer to CryptoTransform::setPadding
    CipherWithPadding(Poco::Crypto::Cipher::Ptr cipher_impl, int padding = 0) 
    : cipher_(cipher_impl)
    , padding_(padding)
    {
    }

    virtual ~CipherWithPadding()
    {
    }

    virtual const std::string& name() const
    {
        return cipher_->name();
    }

    virtual Poco::Crypto::CryptoTransform* createEncryptor() override
    {
        auto ptransform = cipher_->createEncryptor();
        if (ptransform)
            ptransform->setPadding(padding_);
        return ptransform;
    }

    virtual Poco::Crypto::CryptoTransform* createDecryptor() override
    {
        auto ptransform = cipher_->createDecryptor();
        if (ptransform)
            ptransform->setPadding(padding_);
        return ptransform;
    }

protected:
    int padding_;
    Poco::Crypto::Cipher::Ptr cipher_;

protected:
    CipherWithPadding();

private:
    CipherWithPadding(const CipherWithPadding&);
    CipherWithPadding& operator= (const CipherWithPadding&);
};

那么你的函数应该如下所示

std::string Crypto::Encrypt(const std::string &input, const std::string &key)
{
  Poco::Crypto::Cipher::ByteVec iv { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
  Poco::Crypto::Cipher::ByteVec key2 {key.begin(), key.end()};

  CipherWithPadding cipher(Poco::Crypto::CipherFactory::defaultFactory()
      .createCipher(Poco::Crypto::CipherKey("aes128", key2, iv)));

  std::string output = cipher.encryptString(input);

  return std::move(output);
}

在 Poco Crypto 中设置加密填充

Set encryption padding in Poco Crypto

poco-libraries