Move CBC to Transformation API

3 files changed, 296 insertions, 0 deletions

diff --git a/src/modes/cbc/cbc.cpp b/src/modes/cbc/cbc.cpp
new file mode 100644
index 000000000..832f3af4d
--- /dev/null
+++ b/src/modes/cbc/cbc.cpp
@@ -0,0 +1,201 @@
+/*
+* CBC Mode
+* (C) 1999-2007,2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/cbc.h>
+#include <botan/loadstor.h>
+#include <botan/internal/xor_buf.h>
+#include <botan/internal/rounding.h>
+
+namespace Botan {
+
+CBC_Mode::CBC_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
+   m_cipher(cipher),
+   m_padding(padding),
+   m_state(m_cipher->block_size())
+   {
+   if(!m_padding->valid_blocksize(cipher->block_size()))
+      throw std::invalid_argument("Padding " + m_padding->name() +
+                                  " cannot be used with " +
+                                  cipher->name() + "/CBC");
+   }
+
+void CBC_Mode::clear()
+   {
+   m_cipher->clear();
+   m_state.clear();
+   }
+
+std::string CBC_Mode::name() const
+   {
+   return cipher().name() + "/CBC";
+   }
+
+size_t CBC_Mode::update_granularity() const
+   {
+   return cipher().parallel_bytes();
+   }
+
+Key_Length_Specification CBC_Mode::key_spec() const
+   {
+   return cipher().key_spec();
+   }
+
+size_t CBC_Mode::default_nonce_size() const
+   {
+   return cipher().block_size();
+   }
+
+bool CBC_Mode::valid_nonce_length(size_t n) const
+   {
+   return (n == 0 || n == cipher().block_size());
+   }
+
+void CBC_Mode::key_schedule(const byte key[], size_t length)
+   {
+   m_cipher->set_key(key, length);
+   }
+
+secure_vector<byte> CBC_Mode::start(const byte nonce[], size_t nonce_len)
+   {
+   if(!valid_nonce_length(nonce_len))
+      throw Invalid_IV_Length(name(), nonce_len);
+
+   /*
+   * A nonce of zero length means carry the last ciphertext value over
+   * as the new IV, as unfortunately some protocols require this. If
+   * this is the first message then we use an IV of all zeros.
+   */
+   if(nonce_len)
+      m_state.assign(nonce, nonce + nonce_len);
+
+   return secure_vector<byte>();
+   }
+
+size_t CBC_Encryption::minimum_final_size() const
+   {
+   return 0;
+   }
+
+size_t CBC_Encryption::output_length(size_t input_length) const
+   {
+   return round_up(input_length, cipher().block_size());
+   }
+
+void CBC_Encryption::update(secure_vector<byte>& buffer, size_t offset)
+   {
+   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+   const size_t sz = buffer.size() - offset;
+   byte* buf = &buffer[offset];
+
+   const size_t BS = cipher().block_size();
+
+   BOTAN_ASSERT(sz % BS == 0, "CBC input is full blocks");
+   const size_t blocks = sz / BS;
+
+   if(blocks)
+      {
+      xor_buf(&buf[0], &state()[0], BS);
+      cipher().encrypt(&buf[0]);
+
+      for(size_t i = 1; i != blocks; ++i)
+         {
+         xor_buf(&buf[BS*i], &buf[BS*(i-1)], BS);
+         cipher().encrypt(&buf[BS*i]);
+         }
+
+      state().assign(&buf[BS*(blocks-1)], &buf[BS*blocks]);
+      }
+   }
+
+void CBC_Encryption::finish(secure_vector<byte>& buffer, size_t offset)
+   {
+   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+   const size_t sz = buffer.size() - offset;
+   //byte* buf = &buffer[offset];
+
+   const size_t BS = cipher().block_size();
+
+   const size_t bytes_in_final_block = sz % BS;
+
+   const size_t pad_bytes = padding().pad_bytes(BS, bytes_in_final_block);
+
+   if((pad_bytes + bytes_in_final_block) % BS)
+      throw std::runtime_error("Did not pad to full block size in " + name());
+
+#if 0
+   const size_t pad_offset = buffer.size();
+   //buffer.resize(checked_add(buffer.size() + pad_bytes));
+   buffer.resize(buffer.size() + pad_bytes);
+
+   padder().pad(&buffer[pad_offset], BS, bytes_in_final_block);
+#else
+   std::vector<byte> pad(BS);
+   padding().pad(&pad[0], BS, bytes_in_final_block);
+
+   buffer.insert(buffer.end(), pad.begin(), pad.begin() + pad_bytes);
+#endif
+
+   update(buffer, offset);
+   }
+
+size_t CBC_Decryption::output_length(size_t input_length) const
+   {
+   return input_length;
+   }
+
+size_t CBC_Decryption::minimum_final_size() const
+   {
+   return cipher().block_size();
+   }
+
+void CBC_Decryption::update(secure_vector<byte>& buffer, size_t offset)
+   {
+   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+   const size_t sz = buffer.size() - offset;
+   byte* buf = &buffer[offset];
+
+   const size_t BS = cipher().block_size();
+
+   BOTAN_ASSERT(sz % BS == 0, "Input is full blocks");
+   size_t blocks = sz / BS;
+
+   secure_vector<byte> temp(update_granularity());
+
+   while(blocks)
+      {
+      const size_t to_proc = std::min(sz, temp.size());
+
+      cipher().decrypt_n(buf, &temp[0], to_proc / BS);
+
+      xor_buf(&temp[0], state_ptr(), BS);
+      xor_buf(&temp[BS], buf, to_proc - BS);
+      copy_mem(state_ptr(), buf + (to_proc - BS), BS);
+
+      copy_mem(buf, &temp[0], to_proc);
+
+      buf += to_proc;
+      blocks -= to_proc / BS;
+      }
+   }
+
+void CBC_Decryption::finish(secure_vector<byte>& buffer, size_t offset)
+   {
+   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+   const size_t sz = buffer.size() - offset;
+
+   const size_t BS = cipher().block_size();
+
+   if(sz == 0 || sz % BS)
+      throw Decoding_Error(name() + ": Ciphertext not a multiple of block size");
+
+   update(buffer, offset);
+
+   const size_t pad_bytes = BS - padding().unpad(&buffer[buffer.size()-BS], BS);
+   buffer.resize(buffer.size() - pad_bytes); // remove padding
+   }
+
+}
diff --git a/src/modes/cbc/cbc.h b/src/modes/cbc/cbc.h
new file mode 100644
index 000000000..d8b3d818d
--- /dev/null
+++ b/src/modes/cbc/cbc.h
@@ -0,0 +1,94 @@
+/*
+* CBC mode
+* (C) 1999-2007,2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_MODE_CBC_H__
+#define BOTAN_MODE_CBC_H__
+
+#include <botan/transform.h>
+#include <botan/block_cipher.h>
+#include <botan/mode_pad.h>
+#include <memory>
+
+namespace Botan {
+
+/**
+* CBC Mode. Only handles full blocks, padding is handled higher up
+*/
+class CBC_Mode : public Transformation
+   {
+   public:
+      secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
+
+      std::string name() const override;
+
+      size_t update_granularity() const override;
+
+      Key_Length_Specification key_spec() const override;
+
+      size_t default_nonce_size() const override;
+
+      bool valid_nonce_length(size_t n) const override;
+
+      void clear();
+   protected:
+      CBC_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding);
+
+      const BlockCipher& cipher() const { return *m_cipher; }
+
+      const BlockCipherModePaddingMethod& padding() const { return *m_padding; }
+
+      secure_vector<byte>& state() { return m_state; }
+
+      byte* state_ptr() { return &m_state[0]; }
+
+   private:
+      void key_schedule(const byte key[], size_t length) override;
+
+      std::unique_ptr<BlockCipher> m_cipher;
+      std::unique_ptr<BlockCipherModePaddingMethod> m_padding;
+      secure_vector<byte> m_state;
+   };
+
+/**
+* CBC Encryption
+*/
+class BOTAN_DLL CBC_Encryption : public CBC_Mode
+   {
+   public:
+      CBC_Encryption(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
+         CBC_Mode(cipher, padding) {}
+
+      void update(secure_vector<byte>& blocks, size_t offset) override;
+
+      void finish(secure_vector<byte>& final_block, size_t offset) override;
+
+      size_t output_length(size_t input_length) const override;
+
+      size_t minimum_final_size() const override;
+   };
+
+/**
+* CBC Decryption
+*/
+class BOTAN_DLL CBC_Decryption : public CBC_Mode
+   {
+   public:
+      CBC_Decryption(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
+         CBC_Mode(cipher, padding) {}
+
+      void update(secure_vector<byte>& blocks, size_t offset) override;
+
+      void finish(secure_vector<byte>& final_block, size_t offset) override;
+
+      size_t output_length(size_t input_length) const override;
+
+      size_t minimum_final_size() const override;
+   };
+
+}
+
+#endif
diff --git a/src/modes/cbc/info.txt b/src/modes/cbc/info.txt
new file mode 100644
index 000000000..767d907b3
--- /dev/null
+++ b/src/modes/cbc/info.txt
@@ -0,0 +1 @@
+define MODE_CBC