1 files changed, 114 insertions, 0 deletions
diff --git a/Libraries/LibCrypto/Cipher/Mode/CBC.h b/Libraries/LibCrypto/Cipher/Mode/CBC.h
new file mode 100644
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+++ b/Libraries/LibCrypto/Cipher/Mode/CBC.h
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2020, Ali Mohammad Pur <ali.mpfard@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibCrypto/Cipher/Mode/Mode.h>
+
+namespace Crypto {
+
+template <typename T>
+class CBC : public Mode<T> {
+public:
+    template <typename... Args>
+    explicit constexpr CBC<T>(Args... args)
+        : Mode<T>(args...)
+    {
+    }
+
+    virtual Optional<ByteBuffer> encrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
+    {
+        auto length = in.size();
+        if (length == 0)
+            return {};
+
+        auto& cipher = this->cipher();
+
+        // FIXME: We should have two of these encrypt/decrypt functions that
+        //        we SFINAE out based on whether the Cipher mode needs an ivec
+        ASSERT(ivec.has_value());
+        const auto* iv = ivec.value().data();
+
+        typename T::BlockType block { cipher.padding_mode() };
+        size_t offset { 0 };
+        auto block_size = cipher.block_size();
+
+        while (length >= block_size) {
+            block.overwrite(in.slice_view(offset, block_size));
+            block.apply_initialization_vector(iv);
+            cipher.encrypt_block(block, block);
+            out.overwrite(offset, block.get().data(), block_size);
+            iv = out.offset_pointer(offset);
+            length -= block_size;
+            offset += block_size;
+        }
+
+        if (length > 0) {
+            block.overwrite(in.slice_view(offset, length));
+            block.apply_initialization_vector(iv);
+            cipher.encrypt_block(block, block);
+            out.overwrite(offset, block.get().data(), block_size);
+            iv = out.offset_pointer(offset);
+        }
+
+        return ByteBuffer::copy(iv, block_size);
+    }
+    virtual void decrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
+    {
+        auto length = in.size();
+        if (length == 0)
+            return;
+
+        auto& cipher = this->cipher();
+
+        ASSERT(ivec.has_value());
+        const auto* iv = ivec.value().data();
+
+        auto block_size = cipher.block_size();
+
+        // if the data is not aligned, it's not correct encrypted data
+        // FIXME (ponder): Should we simply decrypt as much as we can?
+        ASSERT(length % block_size == 0);
+
+        typename T::BlockType block { cipher.padding_mode() };
+        size_t offset { 0 };
+
+        while (length > 0) {
+            auto* slice = in.offset_pointer(offset);
+            block.overwrite(slice, block_size);
+            cipher.decrypt_block(block, block);
+            block.apply_initialization_vector(iv);
+            auto decrypted = block.get();
+            out.overwrite(offset, decrypted.data(), decrypted.size());
+            iv = slice;
+            length -= block_size;
+            offset += block_size;
+        }
+        this->prune_padding(out);
+    }
+};
+
+}