2 files changed, 109 insertions, 23 deletions

diff --git a/src/modes/ctr/ctr.cpp b/src/modes/ctr/ctr.cpp
index 9eb42ec5a..d458d7848 100644
--- a/src/modes/ctr/ctr.cpp
+++ b/src/modes/ctr/ctr.cpp
@@ -1,6 +1,6 @@
 /*
 * CTR Mode
-* (C) 1999-2007 Jack Lloyd
+* (C) 1999-2009 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
 */
@@ -11,12 +11,21 @@
 
 namespace Botan {
 
+namespace {
+
+const u32bit PARALLEL_BLOCKS = BOTAN_PARALLEL_BLOCKS_CTR;
+
+}
+
 /*
 * CTR-BE Constructor
 */
-CTR_BE::CTR_BE(BlockCipher* ciph) :
-   BlockCipherMode(ciph, "CTR-BE", ciph->BLOCK_SIZE, 1)
+CTR_BE::CTR_BE(BlockCipher* ciph) : cipher(ciph)
    {
+   position = 0;
+
+   counter.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS);
+   enc_buffer.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS);
    }
 
 /*
@@ -24,39 +33,88 @@ CTR_BE::CTR_BE(BlockCipher* ciph) :
 */
 CTR_BE::CTR_BE(BlockCipher* ciph, const SymmetricKey& key,
                const InitializationVector& iv) :
-   BlockCipherMode(ciph, "CTR-BE", ciph->BLOCK_SIZE, 1)
+   cipher(ciph)
    {
-   set_key(key);
+   position = 0;
+
+   counter.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS);
+   enc_buffer.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS);
+
+   cipher->set_key(key);
    set_iv(iv);
    }
 
 /*
+* CTR_BE Destructor
+*/
+CTR_BE::~CTR_BE()
+   {
+   delete cipher;
+   }
+
+/*
+* Return the name of this type
+*/
+std::string CTR_BE::name() const
+   {
+   return ("CTR-BE/" + cipher->name());
+   }
+
+/*
+* Set CTR-BE IV
+*/
+void CTR_BE::set_iv(const InitializationVector& iv)
+   {
+   const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE;
+
+   if(iv.length() != BLOCK_SIZE)
+      throw Invalid_IV_Length(name(), iv.length());
+
+   enc_buffer.clear();
+   position = 0;
+
+   counter.copy(0, iv.begin(), iv.length());
+
+   for(u32bit i = 1; i != PARALLEL_BLOCKS; ++i)
+      {
+      counter.copy(i*BLOCK_SIZE,
+                   counter.begin() + (i-1)*BLOCK_SIZE, BLOCK_SIZE);
+
+      for(s32bit j = BLOCK_SIZE - 1; j >= 0; --j)
+         if(++counter[i*BLOCK_SIZE+j])
+            break;
+      }
+
+   cipher->encrypt_n(counter, enc_buffer, PARALLEL_BLOCKS);
+   }
+
+/*
 * CTR-BE Encryption/Decryption
 */
 void CTR_BE::write(const byte input[], u32bit length)
    {
-   u32bit copied = std::min(BLOCK_SIZE - position, length);
-   xor_buf(buffer + position, input, copied);
-   send(buffer + position, copied);
+   u32bit copied = std::min(enc_buffer.size() - position, length);
+   xor_buf(enc_buffer + position, input, copied);
+   send(enc_buffer + position, copied);
    input += copied;
    length -= copied;
    position += copied;
 
-   if(position == BLOCK_SIZE)
+   if(position == enc_buffer.size())
       increment_counter();
 
-   while(length >= BLOCK_SIZE)
+   while(length >= enc_buffer.size())
       {
-      xor_buf(buffer, input, BLOCK_SIZE);
-      send(buffer, BLOCK_SIZE);
+      xor_buf(enc_buffer, input, enc_buffer.size());
+      send(enc_buffer, enc_buffer.size());
 
-      input += BLOCK_SIZE;
-      length -= BLOCK_SIZE;
+      input += enc_buffer.size();
+      length -= enc_buffer.size();
       increment_counter();
       }
 
-   xor_buf(buffer + position, input, length);
-   send(buffer + position, length);
+   xor_buf(enc_buffer + position, input, length);
+   send(enc_buffer + position, length);
    position += length;
    }
 
@@ -65,10 +123,23 @@ void CTR_BE::write(const byte input[], u32bit length)
 */
 void CTR_BE::increment_counter()
    {
-   for(s32bit j = BLOCK_SIZE - 1; j >= 0; --j)
-      if(++state[j])
-         break;
-   cipher->encrypt(state, buffer);
+   for(u32bit i = 0; i != PARALLEL_BLOCKS; ++i)
+      {
+      byte* this_ctr = counter + i*cipher->BLOCK_SIZE;
+
+      byte last_byte = this_ctr[cipher->BLOCK_SIZE-1];
+      last_byte += PARALLEL_BLOCKS;
+
+      if(this_ctr[cipher->BLOCK_SIZE-1] > last_byte)
+         for(s32bit j = cipher->BLOCK_SIZE - 2; j >= 0; --j)
+            if(++this_ctr[j])
+               break;
+
+      this_ctr[cipher->BLOCK_SIZE-1] = last_byte;
+      }
+
+   cipher->encrypt_n(counter, enc_buffer, PARALLEL_BLOCKS);
+
    position = 0;
    }
 
diff --git a/src/modes/ctr/ctr.h b/src/modes/ctr/ctr.h
index aa0db5761..1948ffe48 100644
--- a/src/modes/ctr/ctr.h
+++ b/src/modes/ctr/ctr.h
@@ -8,22 +8,37 @@
 #ifndef BOTAN_COUNTER_MODE_H__
 #define BOTAN_COUNTER_MODE_H__
 
-#include <botan/modebase.h>
-#include <botan/modebase.h>
+#include <botan/key_filt.h>
+#include <botan/block_cipher.h>
 
 namespace Botan {
 
 /*
 * CTR-BE Mode
 */
-class BOTAN_DLL CTR_BE : public BlockCipherMode
+class BOTAN_DLL CTR_BE : public Keyed_Filter
    {
    public:
+      std::string name() const;
+
+      void set_iv(const InitializationVector&);
+
+      void set_key(const SymmetricKey& key) { cipher->set_key(key); }
+
+      bool valid_keylength(u32bit key_len) const
+         { return cipher->valid_keylength(key_len); }
+
       CTR_BE(BlockCipher*);
       CTR_BE(BlockCipher*, const SymmetricKey&, const InitializationVector&);
+
+      ~CTR_BE();
    private:
       void write(const byte[], u32bit);
       void increment_counter();
+
+      BlockCipher* cipher;
+      SecureVector<byte> counter, enc_buffer;
+      u32bit position;
    };
 
 }