3 files changed, 231 insertions, 0 deletions
diff --git a/modules/modes/cts/cts.cpp b/modules/modes/cts/cts.cpp
new file mode 100644
index 000000000..8af775713
--- /dev/null
+++ b/modules/modes/cts/cts.cpp
@@ -0,0 +1,175 @@
+/*************************************************
+* CTS Mode Source File                           *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/cts.h>
+#include <botan/lookup.h>
+#include <botan/xor_buf.h>
+#include <algorithm>
+
+namespace Botan {
+
+/*************************************************
+* CTS Encryption Constructor                     *
+*************************************************/
+CTS_Encryption::CTS_Encryption(const std::string& cipher_name) :
+   BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
+   {
+   }
+
+/*************************************************
+* CTS Encryption Constructor                     *
+*************************************************/
+CTS_Encryption::CTS_Encryption(const std::string& cipher_name,
+                               const SymmetricKey& key,
+                               const InitializationVector& iv) :
+   BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
+   {
+   set_key(key);
+   set_iv(iv);
+   }
+
+/*************************************************
+* Encrypt a block                                *
+*************************************************/
+void CTS_Encryption::encrypt(const byte block[])
+   {
+   xor_buf(state, block, BLOCK_SIZE);
+   cipher->encrypt(state);
+   send(state, BLOCK_SIZE);
+   }
+
+/*************************************************
+* Encrypt in CTS mode                            *
+*************************************************/
+void CTS_Encryption::write(const byte input[], u32bit length)
+   {
+   u32bit copied = std::min(BUFFER_SIZE - position, length);
+   buffer.copy(position, input, copied);
+   length -= copied;
+   input += copied;
+   position += copied;
+
+   if(length == 0) return;
+
+   encrypt(buffer);
+   if(length > BLOCK_SIZE)
+      {
+      encrypt(buffer + BLOCK_SIZE);
+      while(length > 2*BLOCK_SIZE)
+         {
+         encrypt(input);
+         length -= BLOCK_SIZE;
+         input += BLOCK_SIZE;
+         }
+      position = 0;
+      }
+   else
+      {
+      copy_mem(buffer.begin(), buffer + BLOCK_SIZE, BLOCK_SIZE);
+      position = BLOCK_SIZE;
+      }
+   buffer.copy(position, input, length);
+   position += length;
+   }
+
+/*************************************************
+* Finish encrypting in CTS mode                  *
+*************************************************/
+void CTS_Encryption::end_msg()
+   {
+   if(position < BLOCK_SIZE + 1)
+      throw Exception("CTS_Encryption: insufficient data to encrypt");
+   xor_buf(state, buffer, BLOCK_SIZE);
+   cipher->encrypt(state);
+   SecureVector<byte> cn = state;
+   clear_mem(buffer + position, BUFFER_SIZE - position);
+   encrypt(buffer + BLOCK_SIZE);
+   send(cn, position - BLOCK_SIZE);
+   }
+
+/*************************************************
+* CTS Decryption Constructor                     *
+*************************************************/
+CTS_Decryption::CTS_Decryption(const std::string& cipher_name) :
+   BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
+   {
+   temp.create(BLOCK_SIZE);
+   }
+
+/*************************************************
+* CTS Decryption Constructor                     *
+*************************************************/
+CTS_Decryption::CTS_Decryption(const std::string& cipher_name,
+                               const SymmetricKey& key,
+                               const InitializationVector& iv) :
+   BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
+   {
+   temp.create(BLOCK_SIZE);
+   set_key(key);
+   set_iv(iv);
+   }
+
+/*************************************************
+* Decrypt a block                                *
+*************************************************/
+void CTS_Decryption::decrypt(const byte block[])
+   {
+   cipher->decrypt(block, temp);
+   xor_buf(temp, state, BLOCK_SIZE);
+   send(temp, BLOCK_SIZE);
+   state.copy(block, BLOCK_SIZE);
+   }
+
+/*************************************************
+* Decrypt in CTS mode                            *
+*************************************************/
+void CTS_Decryption::write(const byte input[], u32bit length)
+   {
+   u32bit copied = std::min(BUFFER_SIZE - position, length);
+   buffer.copy(position, input, copied);
+   length -= copied;
+   input += copied;
+   position += copied;
+
+   if(length == 0) return;
+
+   decrypt(buffer);
+   if(length > BLOCK_SIZE)
+      {
+      decrypt(buffer + BLOCK_SIZE);
+      while(length > 2*BLOCK_SIZE)
+         {
+         decrypt(input);
+         length -= BLOCK_SIZE;
+         input += BLOCK_SIZE;
+         }
+      position = 0;
+      }
+   else
+      {
+      copy_mem(buffer.begin(), buffer + BLOCK_SIZE, BLOCK_SIZE);
+      position = BLOCK_SIZE;
+      }
+   buffer.copy(position, input, length);
+   position += length;
+   }
+
+/*************************************************
+* Finish decrypting in CTS mode                  *
+*************************************************/
+void CTS_Decryption::end_msg()
+   {
+   cipher->decrypt(buffer, temp);
+   xor_buf(temp, buffer + BLOCK_SIZE, position - BLOCK_SIZE);
+   SecureVector<byte> xn = temp;
+   copy_mem(buffer + position, xn + (position - BLOCK_SIZE),
+            BUFFER_SIZE - position);
+   cipher->decrypt(buffer + BLOCK_SIZE, temp);
+   xor_buf(temp, state, BLOCK_SIZE);
+   send(temp, BLOCK_SIZE);
+   send(xn, position - BLOCK_SIZE);
+   }
+
+}
diff --git a/modules/modes/cts/cts.h b/modules/modes/cts/cts.h
new file mode 100644
index 000000000..6a07c4eb2
--- /dev/null
+++ b/modules/modes/cts/cts.h
@@ -0,0 +1,46 @@
+/*************************************************
+* CTS Mode Header File                           *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#ifndef BOTAN_CTS_H__
+#define BOTAN_CTS_H__
+
+#include <botan/modebase.h>
+
+namespace Botan {
+
+/*************************************************
+* CTS Encryption                                 *
+*************************************************/
+class BOTAN_DLL CTS_Encryption : public BlockCipherMode
+   {
+   public:
+      CTS_Encryption(const std::string&);
+      CTS_Encryption(const std::string&,
+                     const SymmetricKey&, const InitializationVector&);
+   private:
+      void write(const byte[], u32bit);
+      void end_msg();
+      void encrypt(const byte[]);
+   };
+
+/*************************************************
+* CTS Decryption                                 *
+*************************************************/
+class BOTAN_DLL CTS_Decryption : public BlockCipherMode
+   {
+   public:
+      CTS_Decryption(const std::string&);
+      CTS_Decryption(const std::string&,
+                     const SymmetricKey&, const InitializationVector&);
+   private:
+      void write(const byte[], u32bit);
+      void end_msg();
+      void decrypt(const byte[]);
+      SecureVector<byte> temp;
+   };
+
+}
+
+#endif
diff --git a/modules/modes/cts/modinfo.txt b/modules/modes/cts/modinfo.txt
new file mode 100644
index 000000000..9f36221b4
--- /dev/null
+++ b/modules/modes/cts/modinfo.txt
@@ -0,0 +1,10 @@
+realname "CTS block cipher mode"
+
+define CTS
+
+load_on auto
+
+<add>
+cts.cpp
+cts.h
+</add>