// Copyright (c) 2005-2021 Jay Berkenbilt

// Copyright (c) 2022-2025 Jay Berkenbilt and Manfred Holger

//

// This file is part of qpdf.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//

// Versions of qpdf prior to version 7 were released under the terms

// of version 2.0 of the Artistic License. At your option, you may

// continue to consider qpdf to be licensed under those terms. Please

// see the manual for additional information.

#ifndef QPDFCRYPTOIMPL_HH

#define QPDFCRYPTOIMPL_HH

#include <qpdf/DLL.h>

#include <string>

// This class is part of qpdf's pluggable crypto provider support.

// Most users won't need to know or care about this class, but you can

// use it if you want to supply your own crypto implementation. To do

// so, provide an implementation of QPDFCryptoImpl, ensure that you

// register it by calling QPDFCryptoProvider::registerImpl, and make

// it the default by calling QPDFCryptoProvider::setDefaultProvider.

class QPDF_DLL_CLASS QPDFCryptoImpl

{

  public:

    QPDFCryptoImpl() = default;

    virtual ~QPDFCryptoImpl() = default;

    // Random Number Generation

    virtual void provideRandomData(unsigned char* data, size_t len) = 0;

    // Hashing

    typedef unsigned char MD5_Digest[16];

    virtual void MD5_init() = 0;

    virtual void MD5_update(unsigned char const* data, size_t len) = 0;

    virtual void MD5_finalize() = 0;

    virtual void MD5_digest(MD5_Digest) = 0;

    virtual void SHA2_init(int bits) = 0;

    virtual void SHA2_update(unsigned char const* data, size_t len) = 0;

    virtual void SHA2_finalize() = 0;

    virtual std::string SHA2_digest() = 0;

    // Encryption/Decryption

    // QPDF must support RC4 to be able to work with older PDF files

    // and readers. Search for RC4 in README.md

    // key_len of -1 means treat key_data as a null-terminated string

    virtual void RC4_init(unsigned char const* key_data, int key_len = -1) = 0;

    // out_data = 0 means to encrypt/decrypt in place

    virtual void

    RC4_process(unsigned char const* in_data, size_t len, unsigned char* out_data = nullptr) = 0;

    virtual void RC4_finalize() = 0;

    static size_t constexpr rijndael_buf_size = 16;

    virtual void rijndael_init(

        bool encrypt,

        unsigned char const* key_data,

        size_t key_len,

        bool cbc_mode,

        unsigned char* cbc_block) = 0;

    virtual void rijndael_process(unsigned char* in_data, unsigned char* out_data) = 0;

    virtual void rijndael_finalize() = 0;

};

#endif // QPDFCRYPTOIMPL_HH