cxx: implement "boxes"

9 files changed, 511 insertions, 687 deletions

diff --git a/utils/CMakeLists.txt b/utils/CMakeLists.txt
index ca2c313..4643c5e 100644
--- a/utils/CMakeLists.txt
+++ b/utils/CMakeLists.txt
@@ -2,30 +2,30 @@ find_package(Boost REQUIRED COMPONENTS program_options)
 
 add_executable(util_encrypt_block encrypt_block.cpp block_cmd_parser.hpp block_dumper.hpp data_parsers.hpp)
 target_include_directories(util_encrypt_block PRIVATE ${Boost_INCLUDE_DIRS})
-target_link_libraries(util_encrypt_block libaesni libaesnixx ${Boost_LIBRARIES})
+target_link_libraries(util_encrypt_block libaesnixx ${Boost_LIBRARIES})
 set_target_properties(util_encrypt_block PROPERTIES OUTPUT_NAME encrypt_block)
 
 add_executable(util_decrypt_block decrypt_block.cpp block_cmd_parser.hpp block_dumper.hpp data_parsers.hpp)
 target_include_directories(util_decrypt_block PRIVATE ${Boost_INCLUDE_DIRS})
-target_link_libraries(util_decrypt_block libaesni libaesnixx ${Boost_LIBRARIES})
+target_link_libraries(util_decrypt_block libaesnixx ${Boost_LIBRARIES})
 set_target_properties(util_decrypt_block PROPERTIES OUTPUT_NAME decrypt_block)
 
 add_executable(util_encrypt_file encrypt_file.cpp file_cmd_parser.hpp data_parsers.hpp)
 target_include_directories(util_encrypt_file PRIVATE ${Boost_INCLUDE_DIRS})
-target_link_libraries(util_encrypt_file libaesni libaesnixx ${Boost_LIBRARIES})
+target_link_libraries(util_encrypt_file libaesnixx ${Boost_LIBRARIES})
 set_target_properties(util_encrypt_file PROPERTIES OUTPUT_NAME encrypt_file)
 
 add_executable(util_decrypt_file decrypt_file.cpp file_cmd_parser.hpp data_parsers.hpp)
 target_include_directories(util_decrypt_file PRIVATE ${Boost_INCLUDE_DIRS})
-target_link_libraries(util_decrypt_file libaesni libaesnixx ${Boost_LIBRARIES})
+target_link_libraries(util_decrypt_file libaesnixx ${Boost_LIBRARIES})
 set_target_properties(util_decrypt_file PROPERTIES OUTPUT_NAME decrypt_file)
 
 add_executable(util_encrypt_bmp encrypt_bmp.cpp file_cmd_parser.hpp data_parsers.hpp)
 target_include_directories(util_encrypt_bmp PRIVATE ${Boost_INCLUDE_DIRS})
-target_link_libraries(util_encrypt_bmp libaesni libaesnixx ${Boost_LIBRARIES})
+target_link_libraries(util_encrypt_bmp libaesnixx ${Boost_LIBRARIES})
 set_target_properties(util_encrypt_bmp PROPERTIES OUTPUT_NAME encrypt_bmp)
 
 add_executable(util_decrypt_bmp decrypt_bmp.cpp file_cmd_parser.hpp data_parsers.hpp)
 target_include_directories(util_decrypt_bmp PRIVATE ${Boost_INCLUDE_DIRS})
-target_link_libraries(util_decrypt_bmp libaesni libaesnixx ${Boost_LIBRARIES})
+target_link_libraries(util_decrypt_bmp libaesnixx ${Boost_LIBRARIES})
 set_target_properties(util_decrypt_bmp PROPERTIES OUTPUT_NAME decrypt_bmp)
diff --git a/utils/block_cmd_parser.hpp b/utils/block_cmd_parser.hpp
index c191154..50334e7 100644
--- a/utils/block_cmd_parser.hpp
+++ b/utils/block_cmd_parser.hpp
@@ -12,6 +12,7 @@
 
 #include <aesnixx/all.hpp>
 
+#include <boost/config.hpp>
 #include <boost/program_options.hpp>
 
 #include <ostream>
@@ -20,6 +21,24 @@
 
 namespace
 {
+    BOOST_NORETURN inline void throw_iv_required()
+    {
+        throw boost::program_options::error(
+            "initialization vector is required for the selected mode of operation");
+    }
+
+    BOOST_NORETURN inline void throw_not_implemented(aesni::Algorithm algorithm)
+    {
+        throw boost::program_options::error(
+            "the selected algorithm is not implemented");
+    }
+
+    BOOST_NORETURN inline void throw_not_implemented(aesni::Mode mode)
+    {
+        throw boost::program_options::error(
+            "the selected mode of operation is not implemented");
+    }
+
     class CommandLineParser
     {
     public:
diff --git a/utils/decrypt_block.cpp b/utils/decrypt_block.cpp
index 7c8e773..b9f9d19 100644
--- a/utils/decrypt_block.cpp
+++ b/utils/decrypt_block.cpp
@@ -9,8 +9,6 @@
 #include "block_cmd_parser.hpp"
 #include "block_dumper.hpp"
 
-#include <aesni/all.h>
-
 #include <aesnixx/all.hpp>
 
 #include <boost/program_options.hpp>
@@ -24,7 +22,7 @@
 namespace
 {
     template <aesni::Algorithm algorithm, aesni::Mode mode>
-    bool decrypt_with_mode(
+    void decrypt_with_mode(
         const std::string& key_str,
         std::deque<std::string>& ciphertexts,
         bool verbose = false)
@@ -34,7 +32,7 @@ namespace
         if (aesni::ModeRequiresInitializationVector<mode>())
         {
             if (ciphertexts.empty())
-                return false;
+                throw_iv_required();
 
             aesni::from_string<algorithm>(iv, ciphertexts.front());
             ciphertexts.pop_front();
@@ -73,12 +71,10 @@ namespace
                 std::cout << aesni::to_string<algorithm>(plaintext) << "\n";
             }
         }
-
-        return true;
     }
 
     template <aesni::Algorithm algorithm>
-    bool decrypt_with_algorithm(
+    void decrypt_with_algorithm(
         aesni::Mode mode,
         const std::string& key_str,
         std::deque<std::string>& ciphertexts,
@@ -87,126 +83,100 @@ namespace
         switch (mode)
         {
             case AESNI_ECB:
-                return decrypt_with_mode<algorithm, AESNI_ECB>(key_str, ciphertexts, verbose);
+                decrypt_with_mode<algorithm, AESNI_ECB>(key_str, ciphertexts, verbose);
+                break;
 
             case AESNI_CBC:
-                return decrypt_with_mode<algorithm, AESNI_CBC>(key_str, ciphertexts, verbose);
+                decrypt_with_mode<algorithm, AESNI_CBC>(key_str, ciphertexts, verbose);
+                break;
 
             case AESNI_CFB:
-                return decrypt_with_mode<algorithm, AESNI_CFB>(key_str, ciphertexts, verbose);
+                decrypt_with_mode<algorithm, AESNI_CFB>(key_str, ciphertexts, verbose);
+                break;
 
             case AESNI_OFB:
-                return decrypt_with_mode<algorithm, AESNI_OFB>(key_str, ciphertexts, verbose);
+                decrypt_with_mode<algorithm, AESNI_OFB>(key_str, ciphertexts, verbose);
+                break;
 
             case AESNI_CTR:
-                return decrypt_with_mode<algorithm, AESNI_CTR>(key_str, ciphertexts, verbose);
+                decrypt_with_mode<algorithm, AESNI_CTR>(key_str, ciphertexts, verbose);
+                break;
 
             default:
-                return false;
+                throw_not_implemented(mode);
+                break;
         }
     }
 
-    bool decrypt_using_cxx_api(
+    void decrypt_using_cxx_api(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
         const std::string& key_str,
-        std::deque<std::string> ciphertexts,
+        std::deque<std::string>& ciphertexts,
         bool verbose = false)
     {
         switch (algorithm)
         {
             case AESNI_AES128:
-                return decrypt_with_algorithm<AESNI_AES128>(mode, key_str, ciphertexts, verbose);
+                decrypt_with_algorithm<AESNI_AES128>(mode, key_str, ciphertexts, verbose);
+                break;
 
             case AESNI_AES192:
-                return decrypt_with_algorithm<AESNI_AES192>(mode, key_str, ciphertexts, verbose);
+                decrypt_with_algorithm<AESNI_AES192>(mode, key_str, ciphertexts, verbose);
+                break;
 
             case AESNI_AES256:
-                return decrypt_with_algorithm<AESNI_AES256>(mode, key_str, ciphertexts, verbose);
+                decrypt_with_algorithm<AESNI_AES256>(mode, key_str, ciphertexts, verbose);
+                break;
 
             default:
-                return false;
+                throw_not_implemented(algorithm);
+                break;
         }
     }
 
-    template <aesni::Algorithm algorithm>
-    bool decrypt_using_boxes_with_algorithm(
-        const AesNI_BoxKey& box_key,
-        aesni::Mode mode,
-        const std::string& key,
-        std::deque<std::string> ciphertexts)
+    void decrypt_using_particular_box(
+        aesni::Box& box,
+        std::deque<std::string>& ciphertexts)
     {
-        AesNI_BoxBlock iv;
-        AesNI_BoxBlock* iv_ptr = nullptr;
-
-        if (aesni::mode_requires_initialization_vector(mode))
-        {
-            if (ciphertexts.empty())
-                return false;
-
-            aesni::from_string<algorithm>(iv.aes_block, ciphertexts.front());
-            iv_ptr = &iv;
-            ciphertexts.pop_front();
-        }
-
-        AesNI_Box box;
-        aesni_box_init(
-            &box,
-            algorithm,
-            &box_key,
-            mode,
-            iv_ptr,
-            aesni::ErrorDetailsThrowsInDestructor());
-
         while (!ciphertexts.empty())
         {
-            AesNI_BoxBlock ciphertext;
-            aesni::from_string<algorithm>(ciphertext.aes_block, ciphertexts.front());
+            aesni::Box::Block ciphertext;
+            box.parse_block(ciphertext, ciphertexts.front());
             ciphertexts.pop_front();
 
-            AesNI_BoxBlock plaintext;
-            aesni_box_decrypt_block(
-                &box,
-                &ciphertext,
-                &plaintext,
-                aesni::ErrorDetailsThrowsInDestructor());
+            aesni::Box::Block plaintext;
+            box.decrypt_block(ciphertext, plaintext);
 
-            std::cout << aesni::to_string<algorithm>(plaintext.aes_block) << "\n";
+            std::cout << box.format_block(plaintext) << "\n";
         }
-
-        return true;
     }
 
-    bool decrypt_using_boxes(
+    void decrypt_using_boxes(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
-        const std::string& key,
-        std::deque<std::string> ciphertexts)
+        const std::string& key_str,
+        std::deque<std::string>& ciphertexts)
     {
-        AesNI_BoxKey box_key;
+        aesni::Box::Key key;
+        aesni::Box::parse_key(key, algorithm, key_str);
 
-        switch (algorithm)
+        if (aesni::mode_requires_initialization_vector(mode))
         {
-            case AESNI_AES128:
-                aesni::from_string<AESNI_AES128>(
-                    box_key.aes128_key, key);
-                return decrypt_using_boxes_with_algorithm<AESNI_AES128>(
-                    box_key, mode, key, ciphertexts);
-
-            case AESNI_AES192:
-                aesni::from_string<AESNI_AES192>(
-                    box_key.aes192_key, key);
-                return decrypt_using_boxes_with_algorithm<AESNI_AES192>(
-                    box_key, mode, key, ciphertexts);
+            if (ciphertexts.empty())
+                throw_iv_required();
 
-            case AESNI_AES256:
-                aesni::from_string<AESNI_AES256>(
-                    box_key.aes256_key, key);
-                return decrypt_using_boxes_with_algorithm<AESNI_AES256>(
-                    box_key, mode, key, ciphertexts);
+            aesni::Box::Block iv;
+            aesni::Box::parse_block(iv, algorithm, ciphertexts.front());
+            ciphertexts.pop_front();
 
-            default:
-                return false;
+            decrypt_using_particular_box(
+                aesni::Box(algorithm, key, mode, iv), ciphertexts);
+        }
+        else
+        {
+            decrypt_using_particular_box(
+                aesni::Box(algorithm, key), ciphertexts);
         }
     }
 }
@@ -216,62 +186,76 @@ int main(int argc, char** argv)
     try
     {
         CommandLineParser cmd_parser("decrypt_block.exe");
-        cmd_parser.parse(argc, argv);
-
-        if (cmd_parser.requested_help())
+        try
         {
-            std::cout << cmd_parser;
-            return 0;
-        }
+            cmd_parser.parse(argc, argv);
 
-        std::deque<std::string> args{ std::make_move_iterator(cmd_parser.args.begin()),
-                                      std::make_move_iterator(cmd_parser.args.end()) };
-
-        while (!args.empty())
-        {
-            const auto key = args.front();
-            args.pop_front();
+            if (cmd_parser.requested_help())
+            {
+                std::cout << cmd_parser;
+                return 0;
+            }
 
-            std::deque<std::string> ciphertexts;
+            std::deque<std::string> args(
+                std::make_move_iterator(cmd_parser.args.begin()),
+                std::make_move_iterator(cmd_parser.args.end()));
 
             while (!args.empty())
             {
-                if (args.front() == "--")
+                const auto key = args.front();
+                args.pop_front();
+
+                std::deque<std::string> ciphertexts;
+
+                while (!args.empty())
                 {
+                    if (args.front() == "--")
+                    {
+                        args.pop_front();
+                        break;
+                    }
+
+                    ciphertexts.push_back(args.front());
                     args.pop_front();
-                    break;
                 }
 
-                ciphertexts.push_back(args.front());
-                args.pop_front();
+                if (cmd_parser.use_boxes)
+                {
+                    decrypt_using_boxes(
+                        cmd_parser.algorithm,
+                        cmd_parser.mode,
+                        key,
+                        ciphertexts);
+                }
+                else
+                {
+                    decrypt_using_cxx_api(
+                        cmd_parser.algorithm,
+                        cmd_parser.mode,
+                        key,
+                        ciphertexts,
+                        cmd_parser.verbose);
+                }
             }
 
-            const auto success = cmd_parser.use_boxes
-                ? decrypt_using_boxes(cmd_parser.algorithm, cmd_parser.mode, key, ciphertexts)
-                : decrypt_using_cxx_api(cmd_parser.algorithm, cmd_parser.mode, key, ciphertexts, cmd_parser.verbose);
-
-            if (!success)
-            {
-                std::cout << cmd_parser;
-                return 1;
-            }
+            return 0;
+        }
+        catch (const boost::program_options::error& e)
+        {
+            std::cerr << "Usage error: " << e.what() << "\n";
+            std::cerr << cmd_parser;
+            return 1;
+        }
+        catch (const aesni::Error& e)
+        {
+            std::cerr << e;
+            return 1;
         }
-
-        return 0;
-    }
-    catch (const boost::program_options::error& e)
-    {
-        std::cerr << "Usage error: " << e.what() << "\n";
-        return 1;
-    }
-    catch (const aesni::Error& e)
-    {
-        std::cerr << e;
-        return 1;
     }
     catch (const std::exception& e)
     {
         std::cerr << e.what() << "\n";
         return 1;
     }
+    return 0;
 }
diff --git a/utils/decrypt_bmp.cpp b/utils/decrypt_bmp.cpp
index 802283d..559b5d5 100644
--- a/utils/decrypt_bmp.cpp
+++ b/utils/decrypt_bmp.cpp
@@ -8,8 +8,6 @@
 
 #include "file_cmd_parser.hpp"
 
-#include <aesni/all.h>
-
 #include <aesnixx/all.hpp>
 
 #include <boost/program_options.hpp>
@@ -47,43 +45,35 @@ namespace
 
         std::vector<char> src_buf;
         src_buf.reserve(size);
-        src_buf.assign(std::istreambuf_iterator<char>(ifs),
-                       std::istreambuf_iterator<char>());
+        src_buf.assign(
+            std::istreambuf_iterator<char>(ifs),
+            std::istreambuf_iterator<char>());
         return src_buf;
     }
 
-    void write_file(const std::string& path, const std::vector<char>& src)
+    void write_file(
+        const std::string& path,
+        const std::vector<unsigned char>& src)
     {
         std::ofstream ofs;
         ofs.exceptions(std::ofstream::badbit | std::ofstream::failbit);
         ofs.open(path, std::ofstream::binary);
-        ofs.write(src.data(), src.size());
+        ofs.write(reinterpret_cast<const char*>(src.data()), src.size());
     }
 
-    template <aesni::Algorithm algorithm>
-    bool decrypt_bmp_with_algorithm(
-        const AesNI_BoxKey& box_key,
-        aesni::Mode mode,
+    void decrypt_bmp(
+        aesni::Box& box,
         std::deque<std::string>& args)
     {
-        AesNI_BoxBlock iv;
-        AesNI_BoxBlock* iv_ptr = nullptr;
-
-        if (aesni::mode_requires_initialization_vector(mode))
-        {
-            if (args.empty())
-                return false;
-
-            aesni::from_string<algorithm>(iv.aes_block, args.front());
-            iv_ptr = &iv;
-            args.pop_front();
-        }
-
-        if (args.size() != 2)
-            return false;
+        if (args.empty())
+            throw_src_path_required();
+        const auto src_path = args.front();
+        args.pop_front();
 
-        const auto src_path = args[0];
-        const auto dest_path = args[1];
+        if (args.empty())
+            throw_dest_path_required();
+        const auto dest_path = args.front();
+        args.pop_front();
 
         const auto src_buf = read_file(src_path);
 
@@ -93,79 +83,44 @@ namespace
         const auto cipherpixels = src_buf.data() + header_size;
         const auto cipherpixels_size = src_buf.size() - header_size;
 
-        AesNI_Box box;
-
-        aesni_box_init(
-            &box,
-            algorithm,
-            &box_key,
-            mode,
-            iv_ptr,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::size_t pixels_size;
-
-        aesni_box_decrypt_buffer(
-            &box,
-            cipherpixels,
-            cipherpixels_size,
-            nullptr,
-            &pixels_size,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::vector<char> dest_buf;
-        dest_buf.resize(header_size + pixels_size);
-        std::memcpy(dest_buf.data(), src_buf.data(), header_size);
-
-        aesni_box_decrypt_buffer(
-            &box,
-            cipherpixels,
-            cipherpixels_size,
-            dest_buf.data() + header_size,
-            &pixels_size,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        dest_buf.resize(header_size + pixels_size);
-        write_file(dest_path, dest_buf);
+        const auto pixels = box.decrypt_buffer(
+            cipherpixels, cipherpixels_size);
+
+        std::vector<unsigned char> dest_buf(header_size + pixels.size());
+        std::memcpy(&dest_buf[0], bmp_header, header_size);
+        std::memcpy(&dest_buf[0] + header_size, pixels.data(), pixels.size());
 
-        return true;
+        write_file(dest_path, dest_buf);
     }
 
-    bool decrypt_bmp(
+    void decrypt_bmp(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
         std::deque<std::string>& args)
     {
         if (args.empty())
-            return false;
+            throw_key_required();
+
+        aesni::Box::Key key;
+        aesni::Box::parse_key(key, algorithm, args.front());
+        args.pop_front();
+
+        if (aesni::mode_requires_initialization_vector(mode))
+        {
+            if (args.empty())
+                throw_iv_required();
 
-        AesNI_BoxKey box_key;
+            aesni::Box::Block iv;
+            aesni::Box::parse_block(iv, algorithm, args.front());
+            args.pop_front();
 
-        switch (algorithm)
+            decrypt_bmp(
+                aesni::Box(algorithm, key, mode, iv), args);
+        }
+        else
         {
-            case AESNI_AES128:
-                aesni::from_string<AESNI_AES128>(
-                    box_key.aes128_key, args.front());
-                args.pop_front();
-                return decrypt_bmp_with_algorithm<AESNI_AES128>(
-                    box_key, mode, args);
-
-            case AESNI_AES192:
-                aesni::from_string<AESNI_AES192>(
-                    box_key.aes192_key, args.front());
-                args.pop_front();
-                return decrypt_bmp_with_algorithm<AESNI_AES192>(
-                    box_key, mode, args);
-
-            case AESNI_AES256:
-                aesni::from_string<AESNI_AES256>(
-                    box_key.aes256_key, args.front());
-                args.pop_front();
-                return decrypt_bmp_with_algorithm<AESNI_AES256>(
-                    box_key, mode, args);
-
-            default:
-                return false;
+            decrypt_bmp(
+                aesni::Box(algorithm, key), args);
         }
     }
 }
@@ -175,38 +130,38 @@ int main(int argc, char** argv)
     try
     {
         CommandLineParser cmd_parser("decrypt_bmp.exe");
-        cmd_parser.parse(argc, argv);
-
-        if (cmd_parser.requested_help())
+        try
         {
-            std::cout << cmd_parser;
-            return 0;
-        }
+            cmd_parser.parse(argc, argv);
+
+            if (cmd_parser.requested_help())
+            {
+                std::cout << cmd_parser;
+                return 0;
+            }
 
-        std::deque<std::string> args{ std::make_move_iterator(cmd_parser.args.begin()),
-                                      std::make_move_iterator(cmd_parser.args.end()) };
+            std::deque<std::string> args(
+                std::make_move_iterator(cmd_parser.args.begin()),
+                std::make_move_iterator(cmd_parser.args.end()));
 
-        if (!decrypt_bmp(cmd_parser.algorithm, cmd_parser.mode, args))
+            decrypt_bmp(cmd_parser.algorithm, cmd_parser.mode, args);
+        }
+        catch (const boost::program_options::error& e)
         {
-            std::cout << cmd_parser;
+            std::cerr << "Usage error: " << e.what() << "\n";
+            std::cerr << cmd_parser;
+            return 1;
+        }
+        catch (const aesni::Error& e)
+        {
+            std::cerr << e;
             return 1;
         }
-
-        return 0;
-    }
-    catch (const boost::program_options::error& e)
-    {
-        std::cerr << "Usage error: " << e.what() << "\n";
-        return 1;
-    }
-    catch (const aesni::Error& e)
-    {
-        std::cerr << e;
-        return 1;
     }
     catch (const std::exception& e)
     {
         std::cerr << e.what() << "\n";
         return 1;
     }
+    return 0;
 }
diff --git a/utils/decrypt_file.cpp b/utils/decrypt_file.cpp
index d8c42c4..092b249 100644
--- a/utils/decrypt_file.cpp
+++ b/utils/decrypt_file.cpp
@@ -8,8 +8,6 @@
 
 #include "file_cmd_parser.hpp"
 
-#include <aesni/all.h>
-
 #include <aesnixx/all.hpp>
 
 #include <boost/program_options.hpp>
@@ -44,118 +42,70 @@ namespace
 
         std::vector<char> src_buf;
         src_buf.reserve(size);
-        src_buf.assign(std::istreambuf_iterator<char>(ifs),
-                       std::istreambuf_iterator<char>());
+        src_buf.assign(
+            std::istreambuf_iterator<char>(ifs),
+            std::istreambuf_iterator<char>());
         return src_buf;
     }
 
-    void write_file(const std::string& path, const std::vector<char>& src)
+    void write_file(
+        const std::string& path,
+        const std::vector<unsigned char>& src)
     {
         std::ofstream ofs;
         ofs.exceptions(std::ofstream::badbit | std::ofstream::failbit);
         ofs.open(path, std::ofstream::binary);
-        ofs.write(src.data(), src.size());
+        ofs.write(reinterpret_cast<const char*>(src.data()), src.size());
     }
 
-    template <aesni::Algorithm algorithm>
-    bool decrypt_file_with_algorithm(
-        const AesNI_BoxKey& box_key,
-        aesni::Mode mode,
+    void decrypt_file(
+        aesni::Box& box,
         std::deque<std::string>& args)
     {
-        AesNI_BoxBlock iv;
-        AesNI_BoxBlock* iv_ptr = nullptr;
-
-        if (aesni::mode_requires_initialization_vector(mode))
-        {
-            if (args.empty())
-                return false;
-
-            aesni::from_string<algorithm>(iv.aes_block, args.front());
-            iv_ptr = &iv;
-            args.pop_front();
-        }
-
-        if (args.size() != 2)
-            return false;
+        if (args.empty())
+            throw_src_path_required();
+        const auto src_path = args.front();
+        args.pop_front();
 
-        const auto src_path = args[0];
-        const auto dest_path = args[1];
+        if (args.empty())
+            throw_dest_path_required();
+        const auto dest_path = args.front();
+        args.pop_front();
 
         const auto src_buf = read_file(src_path);
-
-        AesNI_Box box;
-
-        aesni_box_init(
-            &box,
-            algorithm,
-            &box_key,
-            mode,
-            iv_ptr,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::size_t dest_size;
-
-        aesni_box_decrypt_buffer(
-            &box,
-            src_buf.data(),
-            src_buf.size(),
-            nullptr,
-            &dest_size,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::vector<char> dest_buf;
-        dest_buf.resize(dest_size);
-
-        aesni_box_decrypt_buffer(
-            &box,
-            src_buf.data(),
-            src_buf.size(),
-            dest_buf.data(),
-            &dest_size,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        dest_buf.resize(dest_size);
+        const auto dest_buf = box.decrypt_buffer(
+            src_buf.data(), src_buf.size());
         write_file(dest_path, dest_buf);
-
-        return true;
     }
 
-    bool decrypt_file(
+    void decrypt_file(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
         std::deque<std::string>& args)
     {
         if (args.empty())
-            return false;
+            throw_key_required();
 
-        AesNI_BoxKey box_key;
+        aesni::Box::Key key;
+        aesni::Box::parse_key(key, algorithm, args.front());
+        args.pop_front();
 
-        switch (algorithm)
+        if (aesni::mode_requires_initialization_vector(mode))
         {
-            case AESNI_AES128:
-                aesni::from_string<AESNI_AES128>(
-                    box_key.aes128_key, args.front());
-                args.pop_front();
-                return decrypt_file_with_algorithm<AESNI_AES128>(
-                    box_key, mode, args);
-
-            case AESNI_AES192:
-                aesni::from_string<AESNI_AES192>(
-                    box_key.aes192_key, args.front());
-                args.pop_front();
-                return decrypt_file_with_algorithm<AESNI_AES192>(
-                    box_key, mode, args);
-
-            case AESNI_AES256:
-                aesni::from_string<AESNI_AES256>(
-                    box_key.aes256_key, args.front());
-                args.pop_front();
-                return decrypt_file_with_algorithm<AESNI_AES256>(
-                    box_key, mode, args);
-
-            default:
-                return false;
+            if (args.empty())
+                throw_iv_required();
+
+            aesni::Box::Block iv;
+            aesni::Box::parse_block(iv, algorithm, args.front());
+            args.pop_front();
+
+            decrypt_file(
+                aesni::Box(algorithm, key, mode, iv), args);
+        }
+        else
+        {
+            decrypt_file(
+                aesni::Box(algorithm, key), args);
         }
     }
 }
@@ -165,38 +115,38 @@ int main(int argc, char** argv)
     try
     {
         CommandLineParser cmd_parser("decrypt_file.exe");
-        cmd_parser.parse(argc, argv);
-
-        if (cmd_parser.requested_help())
+        try
         {
-            std::cout << cmd_parser;
-            return 0;
-        }
+            cmd_parser.parse(argc, argv);
 
-        std::deque<std::string> args{ std::make_move_iterator(cmd_parser.args.begin()),
-                                      std::make_move_iterator(cmd_parser.args.end()) };
+            if (cmd_parser.requested_help())
+            {
+                std::cout << cmd_parser;
+                return 0;
+            }
 
-        if (!decrypt_file(cmd_parser.algorithm, cmd_parser.mode, args))
+            std::deque<std::string> args(
+                std::make_move_iterator(cmd_parser.args.begin()),
+                std::make_move_iterator(cmd_parser.args.end()));
+
+            decrypt_file(cmd_parser.algorithm, cmd_parser.mode, args);
+        }
+        catch (const boost::program_options::error& e)
         {
-            std::cout << cmd_parser;
+            std::cerr << "Usage error: " << e.what() << "\n";
+            std::cerr << cmd_parser;
+            return 1;
+        }
+        catch (const aesni::Error& e)
+        {
+            std::cerr << e;
             return 1;
         }
-
-        return 0;
-    }
-    catch (const boost::program_options::error& e)
-    {
-        std::cerr << "Usage error: " << e.what() << "\n";
-        return 1;
-    }
-    catch (const aesni::Error& e)
-    {
-        std::cerr << e;
-        return 1;
     }
     catch (const std::exception& e)
     {
         std::cerr << e.what() << "\n";
         return 1;
     }
+    return 0;
 }
diff --git a/utils/encrypt_block.cpp b/utils/encrypt_block.cpp
index 1a62bda..01ea745 100644
--- a/utils/encrypt_block.cpp
+++ b/utils/encrypt_block.cpp
@@ -9,8 +9,6 @@
 #include "block_cmd_parser.hpp"
 #include "block_dumper.hpp"
 
-#include <aesni/all.h>
-
 #include <aesnixx/all.hpp>
 
 #include <boost/program_options.hpp>
@@ -24,7 +22,7 @@
 namespace
 {
     template <aesni::Algorithm algorithm, aesni::Mode mode>
-    bool encrypt_with_mode(
+    void encrypt_with_mode(
         const std::string& key_str,
         std::deque<std::string>& plaintexts,
         bool verbose = false)
@@ -34,7 +32,7 @@ namespace
         if (aesni::ModeRequiresInitializationVector<mode>::value)
         {
             if (plaintexts.empty())
-                return false;
+                throw_iv_required();
 
             aesni::from_string<algorithm>(iv, plaintexts.front());
             plaintexts.pop_front();
@@ -72,12 +70,10 @@ namespace
                 std::cout << aesni::to_string<algorithm>(ciphertext) << "\n";
             }
         }
-
-        return true;
     }
 
     template <aesni::Algorithm algorithm>
-    bool encrypt_with_algorithm(
+    void encrypt_with_algorithm(
         aesni::Mode mode,
         const std::string& key_str,
         std::deque<std::string>& plaintexts,
@@ -86,26 +82,32 @@ namespace
         switch (mode)
         {
             case AESNI_ECB:
-                return encrypt_with_mode<algorithm, AESNI_ECB>(key_str, plaintexts, verbose);
+                encrypt_with_mode<algorithm, AESNI_ECB>(key_str, plaintexts, verbose);
+                break;
 
             case AESNI_CBC:
-                return encrypt_with_mode<algorithm, AESNI_CBC>(key_str, plaintexts, verbose);
+                encrypt_with_mode<algorithm, AESNI_CBC>(key_str, plaintexts, verbose);
+                break;
 
             case AESNI_CFB:
-                return encrypt_with_mode<algorithm, AESNI_CFB>(key_str, plaintexts, verbose);
+                encrypt_with_mode<algorithm, AESNI_CFB>(key_str, plaintexts, verbose);
+                break;
 
             case AESNI_OFB:
-                return encrypt_with_mode<algorithm, AESNI_OFB>(key_str, plaintexts, verbose);
+                encrypt_with_mode<algorithm, AESNI_OFB>(key_str, plaintexts, verbose);
+                break;
 
             case AESNI_CTR:
-                return encrypt_with_mode<algorithm, AESNI_CTR>(key_str, plaintexts, verbose);
+                encrypt_with_mode<algorithm, AESNI_CTR>(key_str, plaintexts, verbose);
+                break;
 
             default:
-                return false;
+                throw_not_implemented(mode);
+                break;
         }
     }
 
-    bool encrypt_using_cxx_api(
+    void encrypt_using_cxx_api(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
         const std::string& key_str,
@@ -115,97 +117,66 @@ namespace
         switch (algorithm)
         {
             case AESNI_AES128:
-                return encrypt_with_algorithm<AESNI_AES128>(mode, key_str, plaintexts, verbose);
+                encrypt_with_algorithm<AESNI_AES128>(mode, key_str, plaintexts, verbose);
+                break;
 
             case AESNI_AES192:
-                return encrypt_with_algorithm<AESNI_AES192>(mode, key_str, plaintexts, verbose);
+                encrypt_with_algorithm<AESNI_AES192>(mode, key_str, plaintexts, verbose);
+                break;
 
             case AESNI_AES256:
-                return encrypt_with_algorithm<AESNI_AES256>(mode, key_str, plaintexts, verbose);
+                encrypt_with_algorithm<AESNI_AES256>(mode, key_str, plaintexts, verbose);
+                break;
 
             default:
-                return false;
+                throw_not_implemented(algorithm);
+                break;
         }
     }
 
-    template <aesni::Algorithm algorithm>
-    bool encrypt_using_boxes_with_algorithm(
-        const AesNI_BoxKey& box_key,
-        aesni::Mode mode,
-        const std::string& key,
-        std::deque<std::string> plaintexts)
+    void encrypt_using_particular_box(
+        aesni::Box& box,
+        std::deque<std::string>& plaintexts)
     {
-        AesNI_BoxBlock iv;
-        AesNI_BoxBlock* iv_ptr = nullptr;
-
-        if (aesni::mode_requires_initialization_vector(mode))
-        {
-            if (plaintexts.empty())
-                return false;
-
-            aesni::from_string<AESNI_AES128>(iv.aes_block, plaintexts.front());
-            iv_ptr = &iv;
-            plaintexts.pop_front();
-        }
-
-        AesNI_Box box;
-        aesni_box_init(
-            &box,
-            algorithm,
-            &box_key,
-            mode,
-            iv_ptr,
-            aesni::ErrorDetailsThrowsInDestructor());
-
         while (!plaintexts.empty())
         {
-            AesNI_BoxBlock plaintext;
-            aesni::from_string<algorithm>(plaintext.aes_block, plaintexts.front());
+            aesni::Box::Block plaintext;
+            box.parse_block(
+                plaintext, plaintexts.front());
             plaintexts.pop_front();
 
-            AesNI_BoxBlock ciphertext;
-            aesni_box_encrypt_block(
-                &box,
-                &plaintext,
-                &ciphertext,
-                aesni::ErrorDetailsThrowsInDestructor());
+            aesni::Box::Block ciphertext;
+            box.encrypt_block(plaintext, ciphertext);
 
-            std::cout << aesni::to_string<algorithm>(ciphertext.aes_block) << "\n";
+            std::cout << box.format_block(ciphertext) << "\n";
         }
-
-        return true;
     }
 
-    bool encrypt_using_boxes(
+    void encrypt_using_boxes(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
-        const std::string& key,
-        std::deque<std::string> plaintexts)
+        const std::string& key_str,
+        std::deque<std::string>& plaintexts)
     {
-        AesNI_BoxKey box_key;
+        aesni::Box::Key key;
+        aesni::Box::parse_key(key, algorithm, key_str);
 
-        switch (algorithm)
+        if (aesni::mode_requires_initialization_vector(mode))
         {
-            case AESNI_AES128:
-                aesni::from_string<AESNI_AES128>(
-                    box_key.aes128_key, key);
-                return encrypt_using_boxes_with_algorithm<AESNI_AES128>(
-                    box_key, mode, key, plaintexts);
-
-            case AESNI_AES192:
-                aesni::from_string<AESNI_AES192>(
-                    box_key.aes192_key, key);
-                return encrypt_using_boxes_with_algorithm<AESNI_AES192>(
-                    box_key, mode, key, plaintexts);
+            if (plaintexts.empty())
+                throw_iv_required();
 
-            case AESNI_AES256:
-                aesni::from_string<AESNI_AES256>(
-                    box_key.aes256_key, key);
-                return encrypt_using_boxes_with_algorithm<AESNI_AES256>(
-                    box_key, mode, key, plaintexts);
+            aesni::Box::Block iv;
+            aesni::Box::parse_block(iv, algorithm, plaintexts.front());
+            plaintexts.pop_front();
 
-            default:
-                return false;
+            encrypt_using_particular_box(
+                aesni::Box(algorithm, key, mode, iv), plaintexts);
+        }
+        else
+        {
+            encrypt_using_particular_box(
+                aesni::Box(algorithm, key), plaintexts);
         }
     }
 }
@@ -215,62 +186,76 @@ int main(int argc, char** argv)
     try
     {
         CommandLineParser cmd_parser("encrypt_block.exe");
-        cmd_parser.parse(argc, argv);
-
-        if (cmd_parser.requested_help())
+        try
         {
-            std::cout << cmd_parser;
-            return 0;
-        }
-
-        std::deque<std::string> args{ std::make_move_iterator(cmd_parser.args.begin()),
-                                      std::make_move_iterator(cmd_parser.args.end()) };
+            cmd_parser.parse(argc, argv);
 
-        while (!args.empty())
-        {
-            const auto key = args.front();
-            args.pop_front();
+            if (cmd_parser.requested_help())
+            {
+                std::cout << cmd_parser;
+                return 0;
+            }
 
-            std::deque<std::string> plaintexts;
+            std::deque<std::string> args(
+                std::make_move_iterator(cmd_parser.args.begin()),
+                std::make_move_iterator(cmd_parser.args.end()));
 
             while (!args.empty())
             {
-                if (args.front() == "--")
+                const auto key = args.front();
+                args.pop_front();
+
+                std::deque<std::string> plaintexts;
+
+                while (!args.empty())
                 {
+                    if (args.front() == "--")
+                    {
+                        args.pop_front();
+                        break;
+                    }
+
+                    plaintexts.push_back(args.front());
                     args.pop_front();
-                    break;
                 }
 
-                plaintexts.push_back(args.front());
-                args.pop_front();
+                if (cmd_parser.use_boxes)
+                {
+                    encrypt_using_boxes(
+                        cmd_parser.algorithm,
+                        cmd_parser.mode,
+                        key,
+                        plaintexts);
+                }
+                else
+                {
+                    encrypt_using_cxx_api(
+                        cmd_parser.algorithm,
+                        cmd_parser.mode,
+                        key,
+                        plaintexts,
+                        cmd_parser.verbose);
+                }
             }
 
-            const auto success = cmd_parser.use_boxes
-                ? encrypt_using_boxes(cmd_parser.algorithm, cmd_parser.mode, key, plaintexts)
-                : encrypt_using_cxx_api(cmd_parser.algorithm, cmd_parser.mode, key, plaintexts, cmd_parser.verbose);
-
-            if (!success)
-            {
-                std::cout << cmd_parser;
-                return 1;
-            }
+            return 0;
+        }
+        catch (const boost::program_options::error& e)
+        {
+            std::cerr << "Usage error: " << e.what() << "\n";
+            std::cerr << cmd_parser;
+            return 1;
+        }
+        catch (const aesni::Error& e)
+        {
+            std::cerr << e;
+            return 1;
         }
-
-        return 0;
-    }
-    catch (const boost::program_options::error& e)
-    {
-        std::cerr << "Usage error: " << e.what() << "\n";
-        return 1;
-    }
-    catch (const aesni::Error& e)
-    {
-        std::cerr << e;
-        return 1;
     }
     catch (const std::exception& e)
     {
         std::cerr << e.what() << "\n";
         return 1;
     }
+    return 0;
 }
diff --git a/utils/encrypt_bmp.cpp b/utils/encrypt_bmp.cpp
index 7e2ad21..978b954 100644
--- a/utils/encrypt_bmp.cpp
+++ b/utils/encrypt_bmp.cpp
@@ -8,8 +8,6 @@
 
 #include "file_cmd_parser.hpp"
 
-#include <aesni/all.h>
-
 #include <aesnixx/all.hpp>
 
 #include <boost/program_options.hpp>
@@ -47,43 +45,35 @@ namespace
 
         std::vector<char> src_buf;
         src_buf.reserve(size);
-        src_buf.assign(std::istreambuf_iterator<char>(ifs),
-                       std::istreambuf_iterator<char>());
+        src_buf.assign(
+            std::istreambuf_iterator<char>(ifs),
+            std::istreambuf_iterator<char>());
         return src_buf;
     }
 
-    void write_file(const std::string& path, const std::vector<char>& src)
+    void write_file(
+        const std::string& path,
+        const std::vector<unsigned char>& src)
     {
         std::ofstream ofs;
         ofs.exceptions(std::ofstream::badbit | std::ofstream::failbit);
         ofs.open(path, std::ofstream::binary);
-        ofs.write(src.data(), src.size());
+        ofs.write(reinterpret_cast<const char*>(src.data()), src.size());
     }
 
-    template <aesni::Algorithm algorithm>
-    bool encrypt_bmp_with_algorithm(
-        const AesNI_BoxKey& box_key,
-        aesni::Mode mode,
+    void encrypt_bmp(
+        aesni::Box& box,
         std::deque<std::string>& args)
     {
-        AesNI_BoxBlock iv;
-        AesNI_BoxBlock* iv_ptr = nullptr;
-
-        if (aesni::mode_requires_initialization_vector(mode))
-        {
-            if (args.empty())
-                return false;
-
-            aesni::from_string<algorithm>(iv.aes_block, args.front());
-            iv_ptr = &iv;
-            args.pop_front();
-        }
-
-        if (args.size() != 2)
-            return false;
+        if (args.empty())
+            throw_src_path_required();
+        const auto src_path = args.front();
+        args.pop_front();
 
-        const auto src_path = args[0];
-        const auto dest_path = args[1];
+        if (args.empty())
+            throw_dest_path_required();
+        const auto dest_path = args.front();
+        args.pop_front();
 
         const auto src_buf = read_file(src_path);
 
@@ -93,78 +83,44 @@ namespace
         const auto pixels = src_buf.data() + header_size;
         const auto pixels_size = src_buf.size() - header_size;
 
-        AesNI_Box box;
-
-        aesni_box_init(
-            &box,
-            algorithm,
-            &box_key,
-            mode,
-            iv_ptr,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::size_t cipherpixels_size;
-
-        aesni_box_encrypt_buffer(
-            &box,
-            pixels,
-            pixels_size,
-            nullptr,
-            &cipherpixels_size,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::vector<char> dest_buf;
-        dest_buf.resize(header_size + cipherpixels_size);
-        std::memcpy(dest_buf.data(), src_buf.data(), header_size);
-
-        aesni_box_encrypt_buffer(
-            &box,
-            pixels,
-            pixels_size,
-            dest_buf.data() + header_size,
-            &cipherpixels_size,
-            aesni::ErrorDetailsThrowsInDestructor());
+        const auto cipherpixels = box.encrypt_buffer(
+            pixels, pixels_size);
 
-        write_file(dest_path, dest_buf);
+        std::vector<unsigned char> dest_buf(header_size + cipherpixels.size());
+        std::memcpy(&dest_buf[0], bmp_header, header_size);
+        std::memcpy(&dest_buf[0] + header_size, cipherpixels.data(), cipherpixels.size());
 
-        return true;
+        write_file(dest_path, dest_buf);
     }
 
-    bool encrypt_bmp(
+    void encrypt_bmp(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
         std::deque<std::string>& args)
     {
         if (args.empty())
-            return false;
+            throw_key_required();
 
-        AesNI_BoxKey box_key;
+        aesni::Box::Key key;
+        aesni::Box::parse_key(key, algorithm, args.front());
+        args.pop_front();
 
-        switch (algorithm)
+        if (aesni::mode_requires_initialization_vector(mode))
         {
-            case AESNI_AES128:
-                aesni::from_string<AESNI_AES128>(
-                    box_key.aes128_key, args.front());
-                args.pop_front();
-                return encrypt_bmp_with_algorithm<AESNI_AES128>(
-                    box_key, mode, args);
-
-            case AESNI_AES192:
-                aesni::from_string<AESNI_AES192>(
-                    box_key.aes192_key, args.front());
-                args.pop_front();
-                return encrypt_bmp_with_algorithm<AESNI_AES192>(
-                    box_key, mode, args);
-
-            case AESNI_AES256:
-                aesni::from_string<AESNI_AES256>(
-                    box_key.aes256_key, args.front());
-                args.pop_front();
-                return encrypt_bmp_with_algorithm<AESNI_AES256>(
-                    box_key, mode, args);
-
-            default:
-                return false;
+            if (args.empty())
+                throw_iv_required();
+
+            aesni::Box::Block iv;
+            aesni::Box::parse_block(iv, algorithm, args.front());
+            args.pop_front();
+
+            encrypt_bmp(
+                aesni::Box(algorithm, key, mode, iv), args);
+        }
+        else
+        {
+            encrypt_bmp(
+                aesni::Box(algorithm, key), args);
         }
     }
 }
@@ -174,38 +130,38 @@ int main(int argc, char** argv)
     try
     {
         CommandLineParser cmd_parser("encrypt_bmp.exe");
-        cmd_parser.parse(argc, argv);
-
-        if (cmd_parser.requested_help())
+        try
         {
-            std::cout << cmd_parser;
-            return 0;
-        }
+            cmd_parser.parse(argc, argv);
 
-        std::deque<std::string> args{ std::make_move_iterator(cmd_parser.args.begin()),
-                                      std::make_move_iterator(cmd_parser.args.end()) };
+            if (cmd_parser.requested_help())
+            {
+                std::cout << cmd_parser;
+                return 0;
+            }
 
-        if (!encrypt_bmp(cmd_parser.algorithm, cmd_parser.mode, args))
+            std::deque<std::string> args(
+                std::make_move_iterator(cmd_parser.args.begin()),
+                std::make_move_iterator(cmd_parser.args.end()));
+
+            encrypt_bmp(cmd_parser.algorithm, cmd_parser.mode, args);
+        }
+        catch (const boost::program_options::error& e)
         {
-            std::cout << cmd_parser;
+            std::cerr << "Usage error: " << e.what() << "\n";
+            std::cerr << cmd_parser;
+            return 1;
+        }
+        catch (const aesni::Error& e)
+        {
+            std::cerr << e;
             return 1;
         }
-
-        return 0;
-    }
-    catch (const boost::program_options::error& e)
-    {
-        std::cerr << "Usage error: " << e.what() << "\n";
-        return 1;
-    }
-    catch (const aesni::Error& e)
-    {
-        std::cerr << e;
-        return 1;
     }
     catch (const std::exception& e)
     {
         std::cerr << e.what() << "\n";
         return 1;
     }
+    return 0;
 }
diff --git a/utils/encrypt_file.cpp b/utils/encrypt_file.cpp
index 13f2ce1..9b5406c 100644
--- a/utils/encrypt_file.cpp
+++ b/utils/encrypt_file.cpp
@@ -8,8 +8,6 @@
 
 #include "file_cmd_parser.hpp"
 
-#include <aesni/all.h>
-
 #include <aesnixx/all.hpp>
 
 #include <boost/program_options.hpp>
@@ -44,118 +42,70 @@ namespace
 
         std::vector<char> src_buf;
         src_buf.reserve(size);
-        src_buf.assign(std::istreambuf_iterator<char>(ifs),
-                       std::istreambuf_iterator<char>());
+        src_buf.assign(
+            std::istreambuf_iterator<char>(ifs),
+            std::istreambuf_iterator<char>());
         return src_buf;
     }
 
-    void write_file(const std::string& path, const std::vector<char>& src)
+    void write_file(
+        const std::string& path,
+        const std::vector<unsigned char>& src)
     {
         std::ofstream ofs;
         ofs.exceptions(std::ofstream::badbit | std::ofstream::failbit);
         ofs.open(path, std::ofstream::binary);
-        ofs.write(src.data(), src.size());
+        ofs.write(reinterpret_cast<const char*>(src.data()), src.size());
     }
 
-    template <aesni::Algorithm algorithm>
-    bool encrypt_file_with_algorithm(
-        const AesNI_BoxKey& box_key,
-        aesni::Mode mode,
+    void encrypt_file(
+        aesni::Box& box,
         std::deque<std::string>& args)
     {
-        AesNI_BoxBlock iv;
-        AesNI_BoxBlock* iv_ptr = nullptr;
-
-        if (aesni::mode_requires_initialization_vector(mode))
-        {
-            if (args.empty())
-                return false;
-
-            aesni::from_string<algorithm>(iv.aes_block, args.front());
-            iv_ptr = &iv;
-            args.pop_front();
-        }
-
-        if (args.size() != 2)
-            return false;
+        if (args.empty())
+            throw_src_path_required();
+        const auto src_path = args.front();
+        args.pop_front();
 
-        const auto src_path = args[0];
-        const auto dest_path = args[1];
+        if (args.empty())
+            throw_dest_path_required();
+        const auto dest_path = args.front();
+        args.pop_front();
 
         const auto src_buf = read_file(src_path);
-
-        AesNI_Box box;
-
-        aesni_box_init(
-            &box,
-            algorithm,
-            &box_key,
-            mode,
-            iv_ptr,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::size_t dest_size;
-
-        aesni_box_encrypt_buffer(
-            &box,
-            src_buf.data(),
-            src_buf.size(),
-            nullptr,
-            &dest_size,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        std::vector<char> dest_buf;
-        dest_buf.resize(dest_size);
-
-        aesni_box_encrypt_buffer(
-            &box,
-            src_buf.data(),
-            src_buf.size(),
-            dest_buf.data(),
-            &dest_size,
-            aesni::ErrorDetailsThrowsInDestructor());
-
-        dest_buf.resize(dest_size);
+        const auto dest_buf = box.encrypt_buffer(
+            src_buf.data(), src_buf.size());
         write_file(dest_path, dest_buf);
-
-        return true;
     }
 
-    bool encrypt_file(
+    void encrypt_file(
         aesni::Algorithm algorithm,
         aesni::Mode mode,
         std::deque<std::string>& args)
     {
         if (args.empty())
-            return false;
+            throw_key_required();
 
-        AesNI_BoxKey box_key;
+        aesni::Box::Key key;
+        aesni::Box::parse_key(key, algorithm, args.front());
+        args.pop_front();
 
-        switch (algorithm)
+        if (aesni::mode_requires_initialization_vector(mode))
         {
-            case AESNI_AES128:
-                aesni::from_string<AESNI_AES128>(
-                    box_key.aes128_key, args.front());
-                args.pop_front();
-                return encrypt_file_with_algorithm<AESNI_AES128>(
-                    box_key, mode, args);
-
-            case AESNI_AES192:
-                aesni::from_string<AESNI_AES192>(
-                    box_key.aes192_key, args.front());
-                args.pop_front();
-                return encrypt_file_with_algorithm<AESNI_AES192>(
-                    box_key, mode, args);
-
-            case AESNI_AES256:
-                aesni::from_string<AESNI_AES256>(
-                    box_key.aes256_key, args.front());
-                args.pop_front();
-                return encrypt_file_with_algorithm<AESNI_AES256>(
-                    box_key, mode, args);
-
-            default:
-                return false;
+            if (args.empty())
+                throw_iv_required();
+
+            aesni::Box::Block iv;
+            aesni::Box::parse_block(iv, algorithm, args.front());
+            args.pop_front();
+
+            encrypt_file(
+                aesni::Box(algorithm, key, mode, iv), args);
+        }
+        else
+        {
+            encrypt_file(
+                aesni::Box(algorithm, key), args);
         }
     }
 }
@@ -165,38 +115,38 @@ int main(int argc, char** argv)
     try
     {
         CommandLineParser cmd_parser("encrypt_file.exe");
-        cmd_parser.parse(argc, argv);
-
-        if (cmd_parser.requested_help())
+        try
         {
-            std::cout << cmd_parser;
-            return 0;
-        }
+            cmd_parser.parse(argc, argv);
 
-        std::deque<std::string> args{ std::make_move_iterator(cmd_parser.args.begin()),
-                                      std::make_move_iterator(cmd_parser.args.end()) };
+            if (cmd_parser.requested_help())
+            {
+                std::cout << cmd_parser;
+                return 0;
+            }
 
-        if (!encrypt_file(cmd_parser.algorithm, cmd_parser.mode, args))
+            std::deque<std::string> args(
+                std::make_move_iterator(cmd_parser.args.begin()),
+                std::make_move_iterator(cmd_parser.args.end()));
+
+            encrypt_file(cmd_parser.algorithm, cmd_parser.mode, args);
+        }
+        catch (const boost::program_options::error& e)
         {
-            std::cout << cmd_parser;
+            std::cerr << "Usage error: " << e.what() << "\n";
+            std::cerr << cmd_parser;
+            return 1;
+        }
+        catch (const aesni::Error& e)
+        {
+            std::cerr << e;
             return 1;
         }
-
-        return 0;
-    }
-    catch (const boost::program_options::error& e)
-    {
-        std::cerr << "Usage error: " << e.what() << "\n";
-        return 1;
-    }
-    catch (const aesni::Error& e)
-    {
-        std::cerr << e;
-        return 1;
     }
     catch (const std::exception& e)
     {
         std::cerr << e.what() << "\n";
         return 1;
     }
+    return 0;
 }
diff --git a/utils/file_cmd_parser.hpp b/utils/file_cmd_parser.hpp
index f20d80f..78162a6 100644
--- a/utils/file_cmd_parser.hpp
+++ b/utils/file_cmd_parser.hpp
@@ -12,6 +12,7 @@
 
 #include <aesnixx/all.hpp>
 
+#include <boost/config.hpp>
 #include <boost/program_options.hpp>
 
 #include <ostream>
@@ -20,6 +21,30 @@
 
 namespace
 {
+    BOOST_NORETURN inline void throw_key_required()
+    {
+        throw boost::program_options::error(
+            "a key is required but not specified");
+    }
+
+    BOOST_NORETURN inline void throw_iv_required()
+    {
+        throw boost::program_options::error(
+            "initialization vector is required for the selected mode of operation");
+    }
+
+    BOOST_NORETURN inline void throw_src_path_required()
+    {
+        throw boost::program_options::error(
+            "please, specify source file path");
+    }
+
+    BOOST_NORETURN inline void throw_dest_path_required()
+    {
+        throw boost::program_options::error(
+            "please, specify destination file path");
+    }
+
     class CommandLineParser
     {
     public: