1 files changed, 215 insertions, 0 deletions
diff --git a/aesxx/utils/decrypt_block.cpp b/aesxx/utils/decrypt_block.cpp
new file mode 100644
index 0000000..02a3033
--- /dev/null
+++ b/aesxx/utils/decrypt_block.cpp
@@ -0,0 +1,215 @@
+// Copyright (c) 2015 Egor Tensin <Egor.Tensin@gmail.com>
+// This file is part of the "AES tools" project.
+// For details, see https://github.com/egor-tensin/aes-tools.
+// Distributed under the MIT License.
+
+#include "block_cmd_parser.hpp"
+#include "block_dumper.hpp"
+#include "block_input.hpp"
+
+#include <aesxx/all.hpp>
+
+#include <boost/program_options.hpp>
+
+#include <exception>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+namespace
+{
+    template <aes::Algorithm algorithm, aes::Mode mode>
+    void decrypt_with_mode(
+        const Input& input,
+        bool verbose = false)
+    {
+        typename aes::Types<algorithm>::Block iv;
+
+        if (aes::ModeRequiresInitVector<mode>())
+        {
+            aes::from_string<algorithm>(iv, input.iv);
+            if (verbose)
+                dump_iv<algorithm>(iv);
+        }
+
+        typename aes::Types<algorithm>::Key key;
+        aes::from_string<algorithm>(key, input.key);
+        if (verbose)
+            dump_key<algorithm>(key);
+
+        aes::DecryptWrapper<algorithm, mode> decrypt{key, iv};
+        if (verbose)
+            dump_wrapper<algorithm, mode>(decrypt);
+
+        for (const auto& block : input.blocks)
+        {
+            typename aes::Types<algorithm>::Block ciphertext, plaintext;
+            aes::from_string<algorithm>(ciphertext, block);
+
+            decrypt.decrypt_block(ciphertext, plaintext);
+
+            if (verbose)
+            {
+                dump_ciphertext<algorithm>(ciphertext);
+                dump_plaintext<algorithm>(plaintext);
+                dump_next_iv<algorithm, mode>(decrypt);
+            }
+            else
+            {
+                std::cout << aes::to_string<algorithm>(plaintext) << '\n';
+            }
+        }
+    }
+
+    template <aes::Algorithm algorithm>
+    void decrypt_with_algorithm(
+        aes::Mode mode,
+        const Input& input,
+        bool verbose = false)
+    {
+        switch (mode)
+        {
+            case AES_ECB:
+                decrypt_with_mode<algorithm, AES_ECB>(input, verbose);
+                break;
+
+            case AES_CBC:
+                decrypt_with_mode<algorithm, AES_CBC>(input, verbose);
+                break;
+
+            case AES_CFB:
+                decrypt_with_mode<algorithm, AES_CFB>(input, verbose);
+                break;
+
+            case AES_OFB:
+                decrypt_with_mode<algorithm, AES_OFB>(input, verbose);
+                break;
+
+            case AES_CTR:
+                decrypt_with_mode<algorithm, AES_CTR>(input, verbose);
+                break;
+
+            default:
+                throw std::runtime_error("the selected mode of operation is not implemented");
+                break;
+        }
+    }
+
+    void decrypt_using_cxx_api(
+        aes::Algorithm algorithm,
+        aes::Mode mode,
+        const Input& input,
+        bool verbose = false)
+    {
+        switch (algorithm)
+        {
+            case AES_AES128:
+                decrypt_with_algorithm<AES_AES128>(mode, input, verbose);
+                break;
+
+            case AES_AES192:
+                decrypt_with_algorithm<AES_AES192>(mode, input, verbose);
+                break;
+
+            case AES_AES256:
+                decrypt_with_algorithm<AES_AES256>(mode, input, verbose);
+                break;
+
+            default:
+                throw std::runtime_error("the selected algorithm is not implemented");
+                break;
+        }
+    }
+
+    void decrypt_using_particular_box(
+        aes::Box& box,
+        const std::vector<std::string>& blocks)
+    {
+        for (const auto& block : blocks)
+        {
+            aes::Box::Block ciphertext;
+            box.parse_block(ciphertext, block);
+
+            aes::Box::Block plaintext;
+            box.decrypt_block(ciphertext, plaintext);
+            std::cout << box.format_block(plaintext) << '\n';
+        }
+    }
+
+    void decrypt_using_boxes(
+        aes::Algorithm algorithm,
+        aes::Mode mode,
+        const Input& input)
+    {
+        aes::Box::Key key;
+        aes::Box::parse_key(key, algorithm, input.key);
+
+        if (aes::mode_requires_init_vector(mode))
+        {
+            aes::Box::Block iv;
+            aes::Box::parse_block(iv, algorithm, input.iv);
+            aes::Box box{algorithm, key, mode, iv};
+
+            decrypt_using_particular_box(box, input.blocks);
+        }
+        else
+        {
+            aes::Box box{algorithm, key};
+            decrypt_using_particular_box(box, input.blocks);
+        }
+    }
+}
+
+int main(int argc, char** argv)
+{
+    try
+    {
+        BlockSettings settings{argv[0]};
+
+        try
+        {
+            settings.parse(argc, argv);
+        }
+        catch (const boost::program_options::error& e)
+        {
+            settings.usage_error(e);
+            return 1;
+        }
+
+        if (settings.exit_with_usage)
+        {
+            settings.usage();
+            return 0;
+        }
+
+        for (const auto& input : settings.inputs)
+        {
+            if (settings.use_boxes)
+            {
+                decrypt_using_boxes(
+                    settings.algorithm,
+                    settings.mode,
+                    input);
+            }
+            else
+            {
+                decrypt_using_cxx_api(
+                    settings.algorithm,
+                    settings.mode,
+                    input,
+                    settings.verbose);
+            }
+        }
+    }
+    catch (const aes::Error& e)
+    {
+        std::cerr << e;
+        return 1;
+    }
+    catch (const std::exception& e)
+    {
+        std::cerr << e.what() << "\n";
+        return 1;
+    }
+    return 0;
+}