26 files changed, 591 insertions, 654 deletions

diff --git a/checks/bench.cpp b/checks/bench.cpp
index ee34b5233..3deff5136 100644
--- a/checks/bench.cpp
+++ b/checks/bench.cpp
@@ -196,9 +196,7 @@ bool bench_algo(const std::string& algo,
             continue;
 
          filt->set_key(Botan::SymmetricKey(&buf[0], cipher_keylen));
-
-         if(filt->valid_iv_length(cipher_ivlen / 2))
-           filt->set_iv(Botan::InitializationVector(&buf[0], cipher_ivlen));
+         filt->set_iv(Botan::InitializationVector(&buf[0], cipher_ivlen));
 
          Botan::Pipe pipe(filt, new Botan::BitBucket);
          pipe.start_msg();
diff --git a/src/engine/core_engine/core_modes.cpp b/src/engine/core_engine/core_modes.cpp
index 199b71838..cf972dd5c 100644
--- a/src/engine/core_engine/core_modes.cpp
+++ b/src/engine/core_engine/core_modes.cpp
@@ -36,7 +36,7 @@
   #include <botan/ctr.h>
 #endif
 
-#if defined(BOTAN_HAS_XTS)
+#if defined(BOTAN_HAS_MODE_XTS)
   #include <botan/xts.h>
 #endif
 
@@ -141,13 +141,13 @@ Keyed_Filter* get_cipher_mode(const BlockCipher* block_cipher,
 #endif
       }
 
-#if defined(BOTAN_HAS_XTS)
+#if defined(BOTAN_HAS_MODE_XTS)
    if(mode == "XTS")
       {
       if(direction == ENCRYPTION)
-         return new XTS_Encryption(block_cipher->clone());
+         return new Transformation_Filter(new XTS_Encryption(block_cipher->clone()));
       else
-         return new XTS_Decryption(block_cipher->clone());
+         return new Transformation_Filter(new XTS_Decryption(block_cipher->clone()));
       }
 #endif
 
diff --git a/src/filters/aead_filt/aead_filt.cpp b/src/filters/aead_filt/aead_filt.cpp
deleted file mode 100644
index f70b8eafe..000000000
--- a/src/filters/aead_filt/aead_filt.cpp
+++ /dev/null
@@ -1,105 +0,0 @@
-/*
-* Filter interface for AEAD modes
-* (C) 2013 Jack Lloyd
-*
-* Distributed under the terms of the Botan license
-*/
-
-#include <botan/aead_filt.h>
-
-namespace Botan {
-
-AEAD_Filter::AEAD_Filter(AEAD_Mode* aead) :
-   Buffered_Filter(aead->update_granularity(),
-                   aead->minimum_final_size()),
-   m_aead(aead)
-   {
-   }
-
-std::string AEAD_Filter::name() const
-   {
-   return m_aead->name();
-   }
-
-void AEAD_Filter::Nonce_State::update(const InitializationVector& iv)
-   {
-   m_nonce = unlock(iv.bits_of());
-   m_fresh_nonce = true;
-   }
-
-std::vector<byte> AEAD_Filter::Nonce_State::get()
-   {
-   BOTAN_ASSERT(m_fresh_nonce, "The nonce is fresh for this message");
-
-   m_fresh_nonce = false;
-   return m_nonce;
-   }
-
-void AEAD_Filter::set_associated_data(const byte ad[], size_t ad_len)
-   {
-   m_aead->set_associated_data(ad, ad_len);
-   }
-
-void AEAD_Filter::set_iv(const InitializationVector& iv)
-   {
-   m_nonce.update(iv);
-   }
-
-void AEAD_Filter::set_key(const SymmetricKey& key)
-   {
-   m_aead->set_key(key);
-   }
-
-Key_Length_Specification AEAD_Filter::key_spec() const
-   {
-   return m_aead->key_spec();
-   }
-
-bool AEAD_Filter::valid_iv_length(size_t length) const
-   {
-   return m_aead->valid_nonce_length(length);
-   }
-
-void AEAD_Filter::write(const byte input[], size_t input_length)
-   {
-   Buffered_Filter::write(input, input_length);
-   }
-
-void AEAD_Filter::end_msg()
-   {
-   Buffered_Filter::end_msg();
-   }
-
-void AEAD_Filter::start_msg()
-   {
-   send(m_aead->start_vec(m_nonce.get()));
-   }
-
-void AEAD_Filter::buffered_block(const byte input[], size_t input_length)
-   {
-   secure_vector<byte> buf;
-
-   while(input_length)
-      {
-      const size_t take = std::min(m_aead->update_granularity(), input_length);
-
-      buf.resize(take);
-      copy_mem(&buf[0], input, take);
-
-      m_aead->update(buf);
-
-      send(buf);
-
-      input += take;
-      input_length -= take;
-      }
-   }
-
-void AEAD_Filter::buffered_final(const byte input[], size_t input_length)
-   {
-   secure_vector<byte> buf(input, input + input_length);
-   m_aead->finish(buf);
-   send(buf);
-   }
-
-}
diff --git a/src/filters/aead_filt/aead_filt.h b/src/filters/aead_filt/aead_filt.h
index 590a60655..65f73d7d3 100644
--- a/src/filters/aead_filt/aead_filt.h
+++ b/src/filters/aead_filt/aead_filt.h
@@ -1,5 +1,5 @@
 /*
-* Filter interface for AEAD modes
+* Filter interface for AEAD Modes
 * (C) 2013 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
@@ -8,21 +8,18 @@
 #ifndef BOTAN_AEAD_FILTER_H__
 #define BOTAN_AEAD_FILTER_H__
 
-#include <botan/key_filt.h>
-#include <botan/buf_filt.h>
+#include <botan/transform_filter.h>
 #include <botan/aead.h>
-#include <memory>
 
 namespace Botan {
 
 /**
-* Filter interface for AEAD modes like EAX and GCM
+* Filter interface for AEAD Modes
 */
-class BOTAN_DLL AEAD_Filter : public Keyed_Filter,
-                              private Buffered_Filter
+class BOTAN_DLL AEAD_Filter : public Transformation_Filter
    {
    public:
-      AEAD_Filter(AEAD_Mode* aead);
+      AEAD_Filter(AEAD_Mode* aead) : Transformation_Filter(aead) {}
 
       /**
       * Set associated data that is not included in the ciphertext but
@@ -32,39 +29,10 @@ class BOTAN_DLL AEAD_Filter : public Keyed_Filter,
       * @param ad the associated data
       * @param ad_len length of add in bytes
       */
-      void set_associated_data(const byte ad[], size_t ad_len);
-
-      void set_iv(const InitializationVector& iv) override;
-
-      void set_key(const SymmetricKey& key) override;
-
-      Key_Length_Specification key_spec() const override;
-
-      bool valid_iv_length(size_t length) const override;
-
-      std::string name() const override;
-
-   private:
-      void write(const byte input[], size_t input_length) override;
-      void start_msg() override;
-      void end_msg() override;
-
-      void buffered_block(const byte input[], size_t input_length) override;
-      void buffered_final(const byte input[], size_t input_length) override;
-
-      class Nonce_State
+      void set_associated_data(const byte ad[], size_t ad_len)
          {
-         public:
-            void update(const InitializationVector& iv);
-            std::vector<byte> get();
-         private:
-            bool m_fresh_nonce = false;
-            std::vector<byte> m_nonce;
-         };
-
-      Nonce_State m_nonce;
-      std::unique_ptr<AEAD_Mode> m_aead;
-
+         dynamic_cast<AEAD_Mode&>(get_transform()).set_associated_data(ad, ad_len);
+         }
    };
 
 }
diff --git a/src/filters/filters.h b/src/filters/filters.h
index 8fcc2d85d..5973cbf50 100644
--- a/src/filters/filters.h
+++ b/src/filters/filters.h
@@ -28,7 +28,7 @@
 namespace Botan {
 
 /**
-* Stream Cipher Filter.
+* Stream Cipher Filter
 */
 class BOTAN_DLL StreamCipher_Filter : public Keyed_Filter
    {
diff --git a/src/filters/info.txt b/src/filters/info.txt
index b5c03aa45..0c56d8269 100644
--- a/src/filters/info.txt
+++ b/src/filters/info.txt
@@ -13,6 +13,7 @@ pipe_io.cpp
 pipe_rw.cpp
 secqueue.cpp
 threaded_fork.cpp
+transform_filter.cpp
 </source>
 
 <header:public>
@@ -25,6 +26,7 @@ filters.h
 key_filt.h
 pipe.h
 secqueue.h
+transform_filter.h
 </header:public>
 
 <header:internal>
diff --git a/src/filters/modes/xts/xts.cpp b/src/filters/modes/xts/xts.cpp
deleted file mode 100644
index df38614bb..000000000
--- a/src/filters/modes/xts/xts.cpp
+++ /dev/null
@@ -1,409 +0,0 @@
-/*
-* XTS Mode
-* (C) 2009 Jack Lloyd
-*
-* Distributed under the terms of the Botan license
-*/
-
-#include <botan/xts.h>
-#include <botan/internal/xor_buf.h>
-#include <algorithm>
-#include <stdexcept>
-
-namespace Botan {
-
-namespace {
-
-void poly_double(byte tweak[], size_t size)
-   {
-   const byte polynomial = (size == 16) ? 0x87 : 0x1B;
-
-   byte carry = 0;
-   for(size_t i = 0; i != size; ++i)
-      {
-      byte carry2 = (tweak[i] >> 7);
-      tweak[i] = (tweak[i] << 1) | carry;
-      carry = carry2;
-      }
-
-   if(carry)
-      tweak[0] ^= polynomial;
-   }
-
-/* XTS needs to process at least 2 blocks in parallel
-   because block_size+1 bytes are needed at the end
-*/
-size_t xts_parallelism(BlockCipher* cipher)
-   {
-   return std::max<size_t>(cipher->parallel_bytes(),
-                           2 * cipher->block_size());
-   }
-
-Key_Length_Specification xts_key_spec(const BlockCipher& cipher)
-   {
-   const Key_Length_Specification& spec = cipher.key_spec();
-
-   return Key_Length_Specification(2*spec.minimum_keylength(),
-                                   2*spec.maximum_keylength(),
-                                   2*spec.keylength_multiple());
-   }
-
-}
-
-/*
-* XTS_Encryption constructor
-*/
-XTS_Encryption::XTS_Encryption(BlockCipher* ciph) :
-   Buffered_Filter(xts_parallelism(ciph), ciph->block_size() + 1),
-   cipher(ciph)
-   {
-   if(cipher->block_size() != 8 && cipher->block_size() != 16)
-      throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
-
-   cipher2 = cipher->clone();
-   tweak.resize(buffered_block_size());
-   }
-
-/*
-* XTS_Encryption constructor
-*/
-XTS_Encryption::XTS_Encryption(BlockCipher* ciph,
-                               const SymmetricKey& key,
-                               const InitializationVector& iv) :
-   Buffered_Filter(xts_parallelism(ciph), ciph->block_size() + 1),
-   cipher(ciph)
-   {
-   if(cipher->block_size() != 8 && cipher->block_size() != 16)
-       throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
-
-   cipher2 = cipher->clone();
-   tweak.resize(buffered_block_size());
-
-   set_key(key);
-   set_iv(iv);
-   }
-
-/*
-* Return the name
-*/
-std::string XTS_Encryption::name() const
-   {
-   return (cipher->name() + "/XTS");
-   }
-
-Key_Length_Specification XTS_Encryption::key_spec() const
-   {
-   return xts_key_spec(*cipher);
-   }
-
-/*
-* Set new tweak
-*/
-void XTS_Encryption::set_iv(const InitializationVector& iv)
-   {
-   if(!valid_iv_length(iv.length()))
-      throw Invalid_IV_Length(name(), iv.length());
-
-   const size_t blocks_in_tweak = tweak.size() / cipher->block_size();
-
-   tweak.assign(iv.begin(), iv.end());
-   cipher2->encrypt(tweak);
-
-   for(size_t i = 1; i < blocks_in_tweak; ++i)
-      {
-      buffer_insert(tweak, i*cipher->block_size(),
-                    &tweak[(i-1)*cipher->block_size()],
-                    cipher->block_size());
-
-      poly_double(&tweak[i*cipher->block_size()], cipher->block_size());
-      }
-   }
-
-void XTS_Encryption::set_key(const SymmetricKey& key)
-   {
-   size_t key_half = key.length() / 2;
-
-   if(key.length() % 2 == 1 || !cipher->valid_keylength(key_half))
-      throw Invalid_Key_Length(name(), key.length());
-
-   cipher->set_key(key.begin(), key_half);
-   cipher2->set_key(key.begin() + key_half, key_half);
-   }
-
-/*
-* Encrypt in XTS mode
-*/
-void XTS_Encryption::write(const byte input[], size_t length)
-   {
-   Buffered_Filter::write(input, length);
-   }
-/*
-* Finish encrypting in XTS mode
-*/
-void XTS_Encryption::end_msg()
-   {
-   Buffered_Filter::end_msg();
-   }
-
-void XTS_Encryption::buffered_block(const byte input[], size_t length)
-   {
-   const size_t blocks_in_tweak = tweak.size() / cipher->block_size();
-   size_t blocks = length / cipher->block_size();
-
-   secure_vector<byte> temp(tweak.size());
-
-   while(blocks)
-      {
-      size_t to_proc = std::min(blocks, blocks_in_tweak);
-      size_t to_proc_bytes = to_proc * cipher->block_size();
-
-      xor_buf(temp, input, tweak, to_proc_bytes);
-
-      cipher->encrypt_n(&temp[0], &temp[0], to_proc);
-
-      xor_buf(temp, tweak, to_proc_bytes);
-
-      send(temp, to_proc_bytes);
-
-      copy_mem(&tweak[0],
-               &tweak[(to_proc-1)*cipher->block_size()],
-               cipher->block_size());
-
-      poly_double(&tweak[0], cipher->block_size());
-
-      for(size_t i = 1; i < blocks_in_tweak; ++i)
-         {
-         buffer_insert(tweak, i*cipher->block_size(),
-                    &tweak[(i-1)*cipher->block_size()],
-                    cipher->block_size());
-
-         poly_double(&tweak[i*cipher->block_size()], cipher->block_size());
-         }
-
-      input += to_proc * cipher->block_size();
-      blocks -= to_proc;
-      }
-   }
-
-/*
-* Finish encrypting in XTS mode
-*/
-void XTS_Encryption::buffered_final(const byte input[], size_t length)
-   {
-   if(length <= cipher->block_size())
-      throw Encoding_Error("XTS_Encryption: insufficient data to encrypt");
-
-   if(length % cipher->block_size() == 0)
-      {
-      buffered_block(input, length);
-      }
-   else
-      { // steal ciphertext
-
-      size_t leftover_blocks =
-         ((length / cipher->block_size()) - 1) * cipher->block_size();
-
-      buffered_block(input, leftover_blocks);
-
-      input += leftover_blocks;
-      length -= leftover_blocks;
-
-      secure_vector<byte> temp(input, input + length);
-
-      xor_buf(temp, tweak, cipher->block_size());
-      cipher->encrypt(temp);
-      xor_buf(temp, tweak, cipher->block_size());
-
-      poly_double(&tweak[0], cipher->block_size());
-
-      for(size_t i = 0; i != length - cipher->block_size(); ++i)
-         std::swap(temp[i], temp[i + cipher->block_size()]);
-
-      xor_buf(temp, tweak, cipher->block_size());
-      cipher->encrypt(temp);
-      xor_buf(temp, tweak, cipher->block_size());
-
-      send(temp, temp.size());
-      }
-
-   buffer_reset();
-   }
-
-/*
-* XTS_Decryption constructor
-*/
-XTS_Decryption::XTS_Decryption(BlockCipher* ciph) :
-   Buffered_Filter(xts_parallelism(ciph), ciph->block_size() + 1),
-   cipher(ciph)
-   {
-   if(cipher->block_size() != 8 && cipher->block_size() != 16)
-       throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
-
-   cipher2 = ciph->clone();
-   tweak.resize(buffered_block_size());
-   }
-
-/*
-* XTS_Decryption constructor
-*/
-XTS_Decryption::XTS_Decryption(BlockCipher* ciph,
-                               const SymmetricKey& key,
-                               const InitializationVector& iv) :
-   Buffered_Filter(xts_parallelism(ciph), ciph->block_size() + 1),
-   cipher(ciph)
-   {
-   if(cipher->block_size() != 8 && cipher->block_size() != 16)
-       throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
-
-   cipher2 = ciph->clone();
-   tweak.resize(buffered_block_size());
-
-   set_key(key);
-   set_iv(iv);
-   }
-
-/*
-* Return the name
-*/
-std::string XTS_Decryption::name() const
-   {
-   return (cipher->name() + "/XTS");
-   }
-
-Key_Length_Specification XTS_Decryption::key_spec() const
-   {
-   return xts_key_spec(*cipher);
-   }
-
-/*
-* Set new tweak
-*/
-void XTS_Decryption::set_iv(const InitializationVector& iv)
-   {
-   if(!valid_iv_length(iv.length()))
-      throw Invalid_IV_Length(name(), iv.length());
-
-   const size_t blocks_in_tweak = tweak.size() / cipher->block_size();
-
-   tweak.assign(iv.begin(), iv.end());
-   cipher2->encrypt(tweak);
-
-   for(size_t i = 1; i < blocks_in_tweak; ++i)
-      {
-      buffer_insert(tweak, i*cipher->block_size(),
-                 &tweak[(i-1)*cipher->block_size()],
-                 cipher->block_size());
-
-      poly_double(&tweak[i*cipher->block_size()], cipher->block_size());
-      }
-   }
-
-void XTS_Decryption::set_key(const SymmetricKey& key)
-   {
-   size_t key_half = key.length() / 2;
-
-   if(key.length() % 2 == 1 || !cipher->valid_keylength(key_half))
-      throw Invalid_Key_Length(name(), key.length());
-
-   cipher->set_key(key.begin(), key_half);
-   cipher2->set_key(key.begin() + key_half, key_half);
-   }
-
-/*
-* Decrypt in XTS mode
-*/
-void XTS_Decryption::write(const byte input[], size_t length)
-   {
-   Buffered_Filter::write(input, length);
-   }
-
-/*
-* Finish decrypting in XTS mode
-*/
-void XTS_Decryption::end_msg()
-   {
-   Buffered_Filter::end_msg();
-   }
-
-void XTS_Decryption::buffered_block(const byte input[], size_t input_length)
-   {
-   const size_t blocks_in_tweak = tweak.size() / cipher->block_size();
-   size_t blocks = input_length / cipher->block_size();
-
-   secure_vector<byte> temp(tweak.size());
-
-   while(blocks)
-      {
-      size_t to_proc = std::min(blocks, blocks_in_tweak);
-      size_t to_proc_bytes = to_proc * cipher->block_size();
-
-      xor_buf(temp, input, tweak, to_proc_bytes);
-
-      cipher->decrypt_n(&temp[0], &temp[0], to_proc);
-
-      xor_buf(temp, tweak, to_proc_bytes);
-
-      send(temp, to_proc_bytes);
-
-      copy_mem(&tweak[0],
-               &tweak[(to_proc-1)*cipher->block_size()],
-               cipher->block_size());
-
-      poly_double(&tweak[0], cipher->block_size());
-
-      for(size_t i = 1; i < blocks_in_tweak; ++i)
-         {
-         buffer_insert(tweak, i*cipher->block_size(),
-                       &tweak[(i-1)*cipher->block_size()],
-                       cipher->block_size());
-
-         poly_double(&tweak[i*cipher->block_size()], cipher->block_size());
-         }
-
-      input += to_proc * cipher->block_size();
-      blocks -= to_proc;
-      }
-   }
-
-void XTS_Decryption::buffered_final(const byte input[], size_t length)
-   {
-   if(length <= cipher->block_size())
-      throw Decoding_Error("XTS_Decryption: insufficient data to decrypt");
-
-   if(length % cipher->block_size() == 0)
-      {
-      buffered_block(input, length);
-      }
-   else
-      {
-      size_t leftover_blocks =
-         ((length / cipher->block_size()) - 1) * cipher->block_size();
-
-      buffered_block(input, leftover_blocks);
-
-      input += leftover_blocks;
-      length -= leftover_blocks;
-
-      secure_vector<byte> temp(input, input + length);
-      secure_vector<byte> tweak_copy(&tweak[0], &tweak[cipher->block_size()]);
-
-      poly_double(&tweak_copy[0], cipher->block_size());
-
-      xor_buf(temp, tweak_copy, cipher->block_size());
-      cipher->decrypt(temp);
-      xor_buf(temp, tweak_copy, cipher->block_size());
-
-      for(size_t i = 0; i != length - cipher->block_size(); ++i)
-         std::swap(temp[i], temp[i + cipher->block_size()]);
-
-      xor_buf(temp, tweak, cipher->block_size());
-      cipher->decrypt(temp);
-      xor_buf(temp, tweak, cipher->block_size());
-
-      send(temp, length);
-      }
-
-   buffer_reset();
-   }
-
-}
diff --git a/src/filters/modes/xts/xts.h b/src/filters/modes/xts/xts.h
deleted file mode 100644
index 05a779703..000000000
--- a/src/filters/modes/xts/xts.h
+++ /dev/null
@@ -1,91 +0,0 @@
-/*
-* XTS mode, from IEEE P1619
-* (C) 2009 Jack Lloyd
-*
-* Distributed under the terms of the Botan license
-*/
-
-#ifndef BOTAN_XTS_H__
-#define BOTAN_XTS_H__
-
-#include <botan/block_cipher.h>
-#include <botan/key_filt.h>
-#include <botan/buf_filt.h>
-
-namespace Botan {
-
-/**
-* IEEE P1619 XTS Encryption
-*/
-class BOTAN_DLL XTS_Encryption : public Keyed_Filter,
-                                 private Buffered_Filter
-   {
-   public:
-      void set_key(const SymmetricKey& key);
-      void set_iv(const InitializationVector& iv);
-
-      Key_Length_Specification key_spec() const override;
-
-      bool valid_iv_length(size_t iv_len) const
-         { return (iv_len == cipher->block_size()); }
-
-      std::string name() const;
-
-      XTS_Encryption(BlockCipher* ciph);
-
-      XTS_Encryption(BlockCipher* ciph,
-                     const SymmetricKey& key,
-                     const InitializationVector& iv);
-
-      ~XTS_Encryption() { delete cipher; delete cipher2; }
-   private:
-      void write(const byte[], size_t);
-      void end_msg();
-
-      void buffered_block(const byte input[], size_t input_length);
-      void buffered_final(const byte input[], size_t input_length);
-
-      BlockCipher* cipher;
-      BlockCipher* cipher2;
-      secure_vector<byte> tweak;
-   };
-
-/**
-* IEEE P1619 XTS Encryption
-*/
-class BOTAN_DLL XTS_Decryption : public Keyed_Filter,
-                                 private Buffered_Filter
-   {
-   public:
-      void set_key(const SymmetricKey& key);
-      void set_iv(const InitializationVector& iv);
-
-      Key_Length_Specification key_spec() const override;
-
-      bool valid_iv_length(size_t iv_len) const
-         { return (iv_len == cipher->block_size()); }
-
-      std::string name() const;
-
-      XTS_Decryption(BlockCipher* ciph);
-
-      XTS_Decryption(BlockCipher* ciph,
-                     const SymmetricKey& key,
-                     const InitializationVector& iv);
-
-      ~XTS_Decryption() { delete cipher; delete cipher2; }
-   private:
-      void write(const byte[], size_t);
-      void end_msg();
-
-      void buffered_block(const byte input[], size_t input_length);
-      void buffered_final(const byte input[], size_t input_length);
-
-      BlockCipher* cipher;
-      BlockCipher* cipher2;
-      secure_vector<byte> tweak;
-   };
-
-}
-
-#endif
diff --git a/src/filters/transform_filter.cpp b/src/filters/transform_filter.cpp
new file mode 100644
index 000000000..e5820585f
--- /dev/null
+++ b/src/filters/transform_filter.cpp
@@ -0,0 +1,100 @@
+/*
+* Filter interface for Transformations
+* (C) 2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/transform_filter.h>
+
+namespace Botan {
+
+Transformation_Filter::Transformation_Filter(Transformation* transform) :
+   Buffered_Filter(transform->update_granularity(),
+                   transform->minimum_final_size()),
+   m_transform(transform)
+   {
+   }
+
+std::string Transformation_Filter::name() const
+   {
+   return m_transform->name();
+   }
+
+void Transformation_Filter::Nonce_State::update(const InitializationVector& iv)
+   {
+   m_nonce = unlock(iv.bits_of());
+   m_fresh_nonce = true;
+   }
+
+std::vector<byte> Transformation_Filter::Nonce_State::get()
+   {
+   //BOTAN_ASSERT(m_fresh_nonce, "The nonce is fresh for this message");
+
+   if(!m_nonce.empty())
+      m_fresh_nonce = false;
+   return m_nonce;
+   }
+
+void Transformation_Filter::set_iv(const InitializationVector& iv)
+   {
+   printf("set_iv\n");
+   m_nonce.update(iv);
+   }
+
+void Transformation_Filter::set_key(const SymmetricKey& key)
+   {
+   m_transform->set_key(key);
+   }
+
+Key_Length_Specification Transformation_Filter::key_spec() const
+   {
+   return m_transform->key_spec();
+   }
+
+bool Transformation_Filter::valid_iv_length(size_t length) const
+   {
+   return m_transform->valid_nonce_length(length);
+   }
+
+void Transformation_Filter::write(const byte input[], size_t input_length)
+   {
+   Buffered_Filter::write(input, input_length);
+   }
+
+void Transformation_Filter::end_msg()
+   {
+   Buffered_Filter::end_msg();
+   }
+
+void Transformation_Filter::start_msg()
+   {
+   send(m_transform->start_vec(m_nonce.get()));
+   }
+
+void Transformation_Filter::buffered_block(const byte input[], size_t input_length)
+   {
+   secure_vector<byte> buf;
+
+   while(input_length)
+      {
+      const size_t take = std::min(m_transform->update_granularity(), input_length);
+
+      buf.assign(input, input + take);
+      m_transform->update(buf);
+
+      send(buf);
+
+      input += take;
+      input_length -= take;
+      }
+   }
+
+void Transformation_Filter::buffered_final(const byte input[], size_t input_length)
+   {
+   secure_vector<byte> buf(input, input + input_length);
+   m_transform->finish(buf);
+   send(buf);
+   }
+
+}
diff --git a/src/filters/transform_filter.h b/src/filters/transform_filter.h
new file mode 100644
index 000000000..5ad66ba96
--- /dev/null
+++ b/src/filters/transform_filter.h
@@ -0,0 +1,67 @@
+/*
+* Filter interface for Transformations
+* (C) 2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_TRANSFORMATION_FILTER_H__
+#define BOTAN_TRANSFORMATION_FILTER_H__
+
+#include <botan/transform.h>
+#include <botan/key_filt.h>
+#include <botan/buf_filt.h>
+#include <memory>
+
+namespace Botan {
+
+/**
+* Filter interface for Transformations
+*/
+class BOTAN_DLL Transformation_Filter : public Keyed_Filter,
+                                        private Buffered_Filter
+   {
+   public:
+      Transformation_Filter(Transformation* t);
+
+      void set_iv(const InitializationVector& iv) override;
+
+      void set_key(const SymmetricKey& key) override;
+
+      Key_Length_Specification key_spec() const override;
+
+      bool valid_iv_length(size_t length) const override;
+
+      std::string name() const override;
+
+   protected:
+      const Transformation& get_transform() const { return *m_transform; }
+
+      Transformation& get_transform() { return *m_transform; }
+
+   private:
+      void write(const byte input[], size_t input_length) override;
+      void start_msg() override;
+      void end_msg() override;
+
+      void buffered_block(const byte input[], size_t input_length) override;
+      void buffered_final(const byte input[], size_t input_length) override;
+
+      class Nonce_State
+         {
+         public:
+            void update(const InitializationVector& iv);
+            std::vector<byte> get();
+         private:
+            bool m_fresh_nonce = false;
+            std::vector<byte> m_nonce;
+         };
+
+      Nonce_State m_nonce;
+      std::unique_ptr<Transformation> m_transform;
+
+   };
+
+}
+
+#endif
diff --git a/src/aead/aead.cpp b/src/modes/aead/aead.cpp
index 1ec7b4a4a..1ec7b4a4a 100644
--- a/src/aead/aead.cpp
+++ b/src/modes/aead/aead.cpp
diff --git a/src/aead/aead.h b/src/modes/aead/aead.h
index 97f156d60..97f156d60 100644
--- a/src/aead/aead.h
+++ b/src/modes/aead/aead.h
diff --git a/src/aead/eax/eax.cpp b/src/modes/aead/eax/eax.cpp
index c6aaa9e85..c6aaa9e85 100644
--- a/src/aead/eax/eax.cpp
+++ b/src/modes/aead/eax/eax.cpp
diff --git a/src/aead/eax/eax.h b/src/modes/aead/eax/eax.h
index 6815e3ce0..6815e3ce0 100644
--- a/src/aead/eax/eax.h
+++ b/src/modes/aead/eax/eax.h
diff --git a/src/aead/eax/info.txt b/src/modes/aead/eax/info.txt
index 94924e682..94924e682 100644
--- a/src/aead/eax/info.txt
+++ b/src/modes/aead/eax/info.txt
diff --git a/src/aead/gcm/gcm.cpp b/src/modes/aead/gcm/gcm.cpp
index 7b8e0aa36..7b8e0aa36 100644
--- a/src/aead/gcm/gcm.cpp
+++ b/src/modes/aead/gcm/gcm.cpp
diff --git a/src/aead/gcm/gcm.h b/src/modes/aead/gcm/gcm.h
index e1479c27f..e1479c27f 100644
--- a/src/aead/gcm/gcm.h
+++ b/src/modes/aead/gcm/gcm.h
diff --git a/src/aead/gcm/info.txt b/src/modes/aead/gcm/info.txt
index 698cd0803..698cd0803 100644
--- a/src/aead/gcm/info.txt
+++ b/src/modes/aead/gcm/info.txt
diff --git a/src/aead/info.txt b/src/modes/aead/info.txt
index c2985ea85..c2985ea85 100644
--- a/src/aead/info.txt
+++ b/src/modes/aead/info.txt
diff --git a/src/aead/ocb/info.txt b/src/modes/aead/ocb/info.txt
index 8d6a93ed9..8d6a93ed9 100644
--- a/src/aead/ocb/info.txt
+++ b/src/modes/aead/ocb/info.txt
diff --git a/src/aead/ocb/ocb.cpp b/src/modes/aead/ocb/ocb.cpp
index 4cbd8bde8..4cbd8bde8 100644
--- a/src/aead/ocb/ocb.cpp
+++ b/src/modes/aead/ocb/ocb.cpp
diff --git a/src/aead/ocb/ocb.h b/src/modes/aead/ocb/ocb.h
index ea7729348..ea7729348 100644
--- a/src/aead/ocb/ocb.h
+++ b/src/modes/aead/ocb/ocb.h
diff --git a/src/filters/modes/xts/info.txt b/src/modes/info.txt
index 7327298f9..0dcb0cd59 100644
--- a/src/filters/modes/xts/info.txt
+++ b/src/modes/info.txt
@@ -1,4 +1,3 @@
-define XTS
 
 <requires>
 block
diff --git a/src/modes/xts/info.txt b/src/modes/xts/info.txt
new file mode 100644
index 000000000..29b58afe4
--- /dev/null
+++ b/src/modes/xts/info.txt
@@ -0,0 +1 @@
+define MODE_XTS
diff --git a/src/modes/xts/xts.cpp b/src/modes/xts/xts.cpp
new file mode 100644
index 000000000..b4e266c21
--- /dev/null
+++ b/src/modes/xts/xts.cpp
@@ -0,0 +1,321 @@
+/*
+* XTS Mode
+* (C) 2009,2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/xts.h>
+#include <botan/internal/xor_buf.h>
+#include <botan/internal/rounding.h>
+
+namespace Botan {
+
+namespace {
+
+void poly_double(byte tweak[], size_t size)
+   {
+   // Use u64bits here?
+   const byte polynomial = (size == 16) ? 0x87 : 0x1B;
+
+   byte carry = 0;
+   for(size_t i = 0; i != size; ++i)
+      {
+      byte carry2 = (tweak[i] >> 7);
+      tweak[i] = (tweak[i] << 1) | carry;
+      carry = carry2;
+      }
+
+   if(carry)
+      tweak[0] ^= polynomial;
+   }
+
+}
+
+XTS_Mode::XTS_Mode(BlockCipher* cipher) : m_cipher(cipher)
+   {
+   if(m_cipher->block_size() != 8 && m_cipher->block_size() != 16)
+      throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
+
+   m_tweak_cipher.reset(m_cipher->clone());
+   m_tweak.resize(update_granularity());
+   }
+
+void XTS_Mode::clear()
+   {
+   m_cipher->clear();
+   m_tweak_cipher->clear();
+   zeroise(m_tweak);
+   }
+
+std::string XTS_Mode::name() const
+   {
+   return cipher().name() + "/XTS";
+   }
+
+size_t XTS_Mode::update_granularity() const
+   {
+   /* XTS needs to process at least 2 blocks in parallel
+      because block_size+1 bytes are needed at the end
+   */
+   return std::max<size_t>(cipher().parallel_bytes(), 2 * cipher().block_size());
+   }
+
+size_t XTS_Mode::minimum_final_size() const
+   {
+   return cipher().block_size() + 1;
+   }
+
+Key_Length_Specification XTS_Mode::key_spec() const
+   {
+   const Key_Length_Specification spec = cipher().key_spec();
+
+   return Key_Length_Specification(2*spec.minimum_keylength(),
+                                   2*spec.maximum_keylength(),
+                                   2*spec.keylength_multiple());
+   }
+
+size_t XTS_Mode::default_nonce_size() const
+   {
+   return cipher().block_size();
+   }
+
+bool XTS_Mode::valid_nonce_length(size_t n) const
+   {
+   return cipher().block_size() == n;
+   }
+
+void XTS_Mode::key_schedule(const byte key[], size_t length)
+   {
+   const size_t key_half = length / 2;
+
+   if(length % 2 == 1 || !m_cipher->valid_keylength(key_half))
+      throw Invalid_Key_Length(name(), length);
+
+   m_cipher->set_key(&key[0], key_half);
+   m_tweak_cipher->set_key(&key[key_half], key_half);
+   }
+
+secure_vector<byte> XTS_Mode::start(const byte nonce[], size_t nonce_len)
+   {
+   if(!valid_nonce_length(nonce_len))
+      throw Invalid_IV_Length(name(), nonce_len);
+
+   const size_t BS = m_tweak_cipher->block_size();
+   const size_t blocks_in_tweak = update_granularity() / BS;
+
+   copy_mem(&m_tweak[0], nonce, nonce_len);
+   m_tweak_cipher->encrypt(&m_tweak[0]);
+
+   //update_tweak(0);
+
+   for(size_t i = 1; i < blocks_in_tweak; ++i)
+      {
+      copy_mem(&m_tweak[i*BS], &m_tweak[(i-1)*BS], BS);
+      poly_double(&m_tweak[i*BS], BS);
+      }
+
+   return secure_vector<byte>();
+   }
+
+void XTS_Mode::update_tweak(size_t which)
+   {
+   const size_t BS = m_tweak_cipher->block_size();
+
+   //if(which > 0)
+   copy_mem(&m_tweak[0], &m_tweak[(which-1)*BS], BS);
+   poly_double(&m_tweak[0], BS);
+
+   const size_t blocks_in_tweak = update_granularity() / BS;
+
+   for(size_t i = 1; i < blocks_in_tweak; ++i)
+      {
+      copy_mem(&m_tweak[i*BS], &m_tweak[(i-1)*BS], BS);
+      poly_double(&m_tweak[i*BS], BS);
+      }
+   }
+
+size_t XTS_Encryption::output_length(size_t input_length) const
+   {
+   return round_up(input_length, cipher().block_size());
+   }
+
+void XTS_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, "Input is full blocks");
+   size_t blocks = sz / BS;
+
+   const size_t blocks_in_tweak = update_granularity() / BS;
+
+   while(blocks)
+      {
+      const size_t to_proc = std::min(blocks, blocks_in_tweak);
+      const size_t to_proc_bytes = to_proc * BS;
+
+      xor_buf(buf, tweak(), to_proc_bytes);
+      cipher().encrypt_n(buf, buf, to_proc);
+      xor_buf(buf, tweak(), to_proc_bytes);
+
+      buf += to_proc * BS;
+      blocks -= to_proc;
+
+      update_tweak(to_proc);
+      }
+   }
+
+void XTS_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];
+
+   BOTAN_ASSERT(sz >= minimum_final_size(), "Have sufficient final input");
+
+   const size_t BS = cipher().block_size();
+
+   if(sz % BS == 0)
+      {
+      update(buffer, offset);
+      }
+   else
+      {
+      // steal ciphertext
+      const size_t full_blocks = ((sz / BS) - 1) * BS;
+      const size_t final_bytes = sz - full_blocks;
+      BOTAN_ASSERT(final_bytes > BS && final_bytes < 2*BS, "Left over size in expected range");
+
+      secure_vector<byte> last(buf + full_blocks, buf + full_blocks + final_bytes);
+      buffer.resize(full_blocks + offset);
+      update(buffer, offset);
+
+      xor_buf(last, tweak(), BS);
+      cipher().encrypt(last);
+      xor_buf(last, tweak(), BS);
+
+      for(size_t i = 0; i != final_bytes - BS; ++i)
+         std::swap(last[i], last[i + BS]);
+
+      xor_buf(last, tweak() + BS, BS);
+      cipher().encrypt(last);
+      xor_buf(last, tweak() + BS, BS);
+
+      buffer += last;
+      }
+   }
+
+size_t XTS_Decryption::output_length(size_t input_length) const
+   {
+   // might be less
+   return input_length;
+   }
+
+void XTS_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;
+
+   const size_t blocks_in_tweak = update_granularity() / BS;
+
+   while(blocks)
+      {
+      const size_t to_proc = std::min(blocks, blocks_in_tweak);
+      const size_t to_proc_bytes = to_proc * BS;
+
+      xor_buf(buf, tweak(), to_proc_bytes);
+      cipher().decrypt_n(buf, buf, to_proc);
+      xor_buf(buf, tweak(), to_proc_bytes);
+
+      buf += to_proc * BS;
+      blocks -= to_proc;
+
+      update_tweak(to_proc);
+      }
+   }
+
+void XTS_Decryption::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];
+
+   BOTAN_ASSERT(sz >= minimum_final_size(), "Have sufficient final input");
+
+   const size_t BS = cipher().block_size();
+
+   if(sz % BS == 0)
+      {
+      update(buffer, offset);
+      }
+   else
+      {
+      // steal ciphertext
+      const size_t full_blocks = ((sz / BS) - 1) * BS;
+      const size_t final_bytes = sz - full_blocks;
+      BOTAN_ASSERT(final_bytes > BS && final_bytes < 2*BS, "Left over size in expected range");
+
+      secure_vector<byte> last(buf + full_blocks, buf + full_blocks + final_bytes);
+      buffer.resize(full_blocks + offset);
+      update(buffer, offset);
+
+      xor_buf(last, tweak() + BS, BS);
+      cipher().decrypt(last);
+      xor_buf(last, tweak() + BS, BS);
+
+      for(size_t i = 0; i != final_bytes - BS; ++i)
+         std::swap(last[i], last[i + BS]);
+
+      xor_buf(last, tweak(), BS);
+      cipher().decrypt(last);
+      xor_buf(last, tweak(), BS);
+
+      buffer += last;
+      }
+   }
+
+/*
+void XTS_Decryption::buffered_final(const byte input[], size_t length)
+   {
+      size_t leftover_blocks =
+         ((length / BS) - 1) * BS;
+
+      buffered_block(input, leftover_blocks);
+
+      input += leftover_blocks;
+      length -= leftover_blocks;
+
+      secure_vector<byte> temp(input, input + length);
+      secure_vector<byte> tweak_copy(&tweak[0], &tweak[BS]);
+
+      poly_double(&tweak_copy[0], BS);
+
+      xor_buf(temp, tweak_copy, BS);
+      cipher->decrypt(temp);
+      xor_buf(temp, tweak_copy, BS);
+
+      for(size_t i = 0; i != length - BS; ++i)
+         std::swap(temp[i], temp[i + BS]);
+
+      xor_buf(temp, tweak, BS);
+      cipher->decrypt(temp);
+      xor_buf(temp, tweak, BS);
+
+      send(temp, length);
+      }
+
+   buffer_reset();
+   }
+*/
+
+}
diff --git a/src/modes/xts/xts.h b/src/modes/xts/xts.h
new file mode 100644
index 000000000..2163bb447
--- /dev/null
+++ b/src/modes/xts/xts.h
@@ -0,0 +1,86 @@
+/*
+* XTS mode, from IEEE P1619
+* (C) 2009,2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_MODE_XTS_H__
+#define BOTAN_MODE_XTS_H__
+
+#include <botan/transform.h>
+#include <botan/block_cipher.h>
+#include <memory>
+
+namespace Botan {
+
+/**
+* IEEE P1619 XTS Mode
+*/
+class XTS_Mode : public Transformation
+   {
+   public:
+      std::string name() const override;
+
+      secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
+
+      size_t update_granularity() const;
+
+      size_t minimum_final_size() 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:
+      XTS_Mode(BlockCipher* cipher);
+
+      const byte* tweak() const { return &m_tweak[0]; }
+
+      const BlockCipher& cipher() const { return *m_cipher; }
+
+      void update_tweak(size_t last_used);
+
+   private:
+      void key_schedule(const byte key[], size_t length) override;
+
+      std::unique_ptr<BlockCipher> m_cipher, m_tweak_cipher;
+      secure_vector<byte> m_tweak;
+   };
+
+/**
+* IEEE P1619 XTS Encryption
+*/
+class BOTAN_DLL XTS_Encryption : public XTS_Mode
+   {
+   public:
+      XTS_Encryption(BlockCipher* cipher) : XTS_Mode(cipher) {}
+
+      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;
+   };
+
+/**
+* IEEE P1619 XTS Decryption
+*/
+class BOTAN_DLL XTS_Decryption : public XTS_Mode
+   {
+   public:
+      XTS_Decryption(BlockCipher* cipher) : XTS_Mode(cipher) {}
+
+      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;
+   };
+
+}
+
+#endif