1 files changed, 143 insertions, 0 deletions
diff --git a/botan/src/modes/cfb/cfb.cpp b/botan/src/modes/cfb/cfb.cpp
new file mode 100644
index 0000000..a126bd9
--- /dev/null
+++ b/botan/src/modes/cfb/cfb.cpp
@@ -0,0 +1,143 @@
+/*
+* CFB Mode
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/cfb.h>
+#include <botan/parsing.h>
+#include <botan/xor_buf.h>
+#include <algorithm>
+
+namespace Botan {
+
+namespace {
+
+/*
+* Check the feedback size
+*/
+void check_feedback(u32bit BLOCK_SIZE, u32bit FEEDBACK_SIZE, u32bit bits,
+                    const std::string& name)
+   {
+   if(FEEDBACK_SIZE == 0 || FEEDBACK_SIZE > BLOCK_SIZE || bits % 8 != 0)
+      throw Invalid_Argument(name + ": Invalid feedback size " +
+                             to_string(bits));
+   }
+
+}
+
+/*
+* CFB Encryption Constructor
+*/
+CFB_Encryption::CFB_Encryption(BlockCipher* ciph,
+                               u32bit fback_bits) :
+   BlockCipherMode(ciph, "CFB", ciph->BLOCK_SIZE, 1),
+   FEEDBACK_SIZE(fback_bits ? fback_bits / 8: BLOCK_SIZE)
+   {
+   check_feedback(BLOCK_SIZE, FEEDBACK_SIZE, fback_bits, name());
+   }
+
+/*
+* CFB Encryption Constructor
+*/
+CFB_Encryption::CFB_Encryption(BlockCipher* ciph,
+                               const SymmetricKey& key,
+                               const InitializationVector& iv,
+                               u32bit fback_bits) :
+   BlockCipherMode(ciph, "CFB", ciph->BLOCK_SIZE, 1),
+   FEEDBACK_SIZE(fback_bits ? fback_bits / 8: BLOCK_SIZE)
+   {
+   check_feedback(BLOCK_SIZE, FEEDBACK_SIZE, fback_bits, name());
+   set_key(key);
+   set_iv(iv);
+   }
+
+/*
+* Encrypt data in CFB mode
+*/
+void CFB_Encryption::write(const byte input[], u32bit length)
+   {
+   while(length)
+      {
+      u32bit xored = std::min(FEEDBACK_SIZE - position, length);
+      xor_buf(buffer + position, input, xored);
+      send(buffer + position, xored);
+      input += xored;
+      length -= xored;
+      position += xored;
+      if(position == FEEDBACK_SIZE)
+         feedback();
+      }
+   }
+
+/*
+* Do the feedback
+*/
+void CFB_Encryption::feedback()
+   {
+   for(u32bit j = 0; j != BLOCK_SIZE - FEEDBACK_SIZE; ++j)
+      state[j] = state[j + FEEDBACK_SIZE];
+   state.copy(BLOCK_SIZE - FEEDBACK_SIZE, buffer, FEEDBACK_SIZE);
+   cipher->encrypt(state, buffer);
+   position = 0;
+   }
+
+/*
+* CFB Decryption Constructor
+*/
+CFB_Decryption::CFB_Decryption(BlockCipher* ciph,
+                               u32bit fback_bits) :
+   BlockCipherMode(ciph, "CFB", ciph->BLOCK_SIZE, 1),
+   FEEDBACK_SIZE(fback_bits ? fback_bits / 8 : BLOCK_SIZE)
+   {
+   check_feedback(BLOCK_SIZE, FEEDBACK_SIZE, fback_bits, name());
+   }
+
+/*
+* CFB Decryption Constructor
+*/
+CFB_Decryption::CFB_Decryption(BlockCipher* ciph,
+                               const SymmetricKey& key,
+                               const InitializationVector& iv,
+                               u32bit fback_bits) :
+   BlockCipherMode(ciph, "CFB", ciph->BLOCK_SIZE, 1),
+   FEEDBACK_SIZE(fback_bits ? fback_bits / 8 : BLOCK_SIZE)
+   {
+   check_feedback(BLOCK_SIZE, FEEDBACK_SIZE, fback_bits, name());
+   set_key(key);
+   set_iv(iv);
+   }
+
+/*
+* Decrypt data in CFB mode
+*/
+void CFB_Decryption::write(const byte input[], u32bit length)
+   {
+   while(length)
+      {
+      u32bit xored = std::min(FEEDBACK_SIZE - position, length);
+      xor_buf(buffer + position, input, xored);
+      send(buffer + position, xored);
+      buffer.copy(position, input, xored);
+      input += xored;
+      length -= xored;
+      position += xored;
+      if(position == FEEDBACK_SIZE)
+         feedback();
+      }
+   }
+
+/*
+* Do the feedback
+*/
+void CFB_Decryption::feedback()
+   {
+   for(u32bit j = 0; j != BLOCK_SIZE - FEEDBACK_SIZE; ++j)
+      state[j] = state[j + FEEDBACK_SIZE];
+   state.copy(BLOCK_SIZE - FEEDBACK_SIZE, buffer, FEEDBACK_SIZE);
+   cipher->encrypt(state, buffer);
+   position = 0;
+   }
+
+}