crypto_sym.hpp

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//*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2026 Denis Corbin
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author, see the AUTHOR file
/*********************************************************************/

 
#ifndef CRYPTO_SYM_HPP
#define CRYPTO_SYM_HPP
 
extern "C"
{
#if HAVE_GCRYPT_H
#ifndef GCRYPT_NO_DEPRECATED
#define GCRYPT_NO_DEPRECATED
#endif
#include <gcrypt.h>
#endif
}
 
#include "../my_config.h"
#include <string>
 
#include "crypto_module.hpp"
#include "secu_string.hpp"
#include "crypto.hpp"
#include "archive_aux.hpp"
#include "archive_version.hpp"
 
 
namespace libdar
{

 
    inline bool crypto_min_ver_libgcrypt_no_bug()
    {
#if CRYPTO_AVAILABLE
    return gcry_check_version(MIN_VERSION_GCRYPT_HASH_BUG);
#else
    return true;
#endif
    }

 
    class crypto_sym : public crypto_module
    {
    public:
    crypto_sym(const secu_string & password, 
           const archive_version & reading_ver, 
           crypto_algo algo,         
           const std::string & salt, 
           const infinint & iteration_count, 
           hash_algo kdf_hash,       
           bool use_pkcs5            
        );
    crypto_sym(const crypto_sym & ref) { nullify(); copy_from(ref); };
    crypto_sym(crypto_sym && ref) noexcept { try { move_from(std::move(ref)); } catch(...) {} };
    crypto_sym & operator = (const crypto_sym & ref) { detruit(); copy_from(ref); return *this; };
    crypto_sym & operator = (crypto_sym && ref) noexcept { try { detruit(); move_from(std::move(ref)); } catch(...) {} return *this; };
    virtual ~crypto_sym() noexcept { try { detruit(); } catch(...) {} };
 
        // inherited from class crypto_module
 
    virtual U_32 encrypted_block_size_for(U_32 clear_block_size) override;
    virtual U_32 clear_block_allocated_size_for(U_32 clear_block_size) override;
    virtual U_32 encrypt_data(const infinint & block_num,
                  const char *clear_buf,
                  const U_32 clear_size,
                  const U_32 clear_allocated,
                  char *crypt_buf, U_32 crypt_size) override;
    virtual U_32 decrypt_data(const infinint & block_num,
                  const char *crypt_buf,
                  const U_32 crypt_size,
                  char *clear_buf,
                  U_32 clear_size) override;
    virtual std::unique_ptr<crypto_module> clone() const override;

    const std::string & get_salt() const { return sel; };
 

    static size_t max_key_len(crypto_algo algo);

    static size_t max_key_len_libdar(crypto_algo algo);

    static bool is_a_strong_password(crypto_algo algo, const secu_string & password);
 
    private:
    std::string sel;               
#if CRYPTO_AVAILABLE
    archive_version reading_ver;   
    crypto_algo algo;              
    secu_string hashed_password;   
    secu_string essiv_password;    
    gcry_cipher_hd_t main_clef;    
    gcry_cipher_hd_t essiv_clef;   
    size_t algo_block_size;        
    unsigned char *ivec;           
 
    void init_hashed_password(const secu_string & password,
                  bool use_pkcs5,
                  const std::string & salt,
                  infinint iteration_count,
                  hash_algo kdf_hash,
                  crypto_algo algo);
    void init_essiv_password(const secu_string & key,
                 unsigned int IV_hashing);
    void init_main_clef(const secu_string & password, 
                crypto_algo algo              
        );
    void init_essiv_clef(const secu_string & essiv_password,
                 U_I IV_cipher,
                 U_I main_cipher_algo_block_size);
    void init_algo_block_size(crypto_algo algo);
    void init_ivec(crypto_algo algo, size_t algo_block_size);
 
    void nullify();
    void detruit();
    void copy_from(const crypto_sym & ref);
    void move_from(crypto_sym && ref);


 
    static void get_IV_cipher_and_hashing(const archive_version & ver, U_I main_cipher, U_I & cipher, U_I & hashing);


    static void make_ivec(const infinint & ref,
                  unsigned char *ivec,
                  U_I size,
                  const gcry_cipher_hd_t & IVkey);

    static secu_string pkcs5_pass2key(const secu_string & password,         
                      const std::string & salt,             
                      U_I iteration_count,                  
                      U_I hash_gcrypt,                      
                      U_I output_length);                   

    static secu_string argon2_pass2key(const secu_string & password,
                       const std::string & salt,
                       U_I iteration_count,
                       U_I output_length);

    static U_I get_algo_id(crypto_algo algo);

    static std::string generate_salt(U_I size);
 
#ifdef LIBDAR_NO_OPTIMIZATION
    static bool self_tested;
    static void self_test(void);
#endif
 
#else
    void nullify() { throw Ecompilation(gettext("Strong encryption support (libgcrypt)")); };
    void detruit() { throw Ecompilation(gettext("Strong encryption support (libgcrypt)")); };
    void copy_from(const crypto_sym & ref) { throw Ecompilation(gettext("Strong encryption support (libgcrypt)")); };
    void move_from(crypto_sym && ref) { throw Ecompilation(gettext("Strong encryption support (libgcrypt)")); };
#endif
    };

 
} // end of namespace
 
#endif