1 files changed, 65 insertions, 0 deletions
diff --git a/modules/modes/ofb/ofb.cpp b/modules/modes/ofb/ofb.cpp
new file mode 100644
index 000000000..db254d329
--- /dev/null
+++ b/modules/modes/ofb/ofb.cpp
@@ -0,0 +1,65 @@
+/*************************************************
+* OFB Mode Source File                           *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/ofb.h>
+#include <botan/lookup.h>
+#include <botan/xor_buf.h>
+#include <algorithm>
+
+namespace Botan {
+
+/*************************************************
+* OFB Constructor                                *
+*************************************************/
+OFB::OFB(const std::string& cipher_name) :
+   BlockCipherMode(cipher_name, "OFB", block_size_of(cipher_name), 2)
+   {
+   }
+
+/*************************************************
+* OFB Constructor                                *
+*************************************************/
+OFB::OFB(const std::string& cipher_name, const SymmetricKey& key,
+         const InitializationVector& iv) :
+   BlockCipherMode(cipher_name, "OFB", block_size_of(cipher_name), 2)
+   {
+   set_key(key);
+   set_iv(iv);
+   }
+
+/*************************************************
+* OFB Encryption/Decryption                      *
+*************************************************/
+void OFB::write(const byte input[], u32bit length)
+   {
+   u32bit copied = std::min(BLOCK_SIZE - position, length);
+   xor_buf(buffer, input, state + position, copied);
+   send(buffer, copied);
+   input += copied;
+   length -= copied;
+   position += copied;
+
+   if(position == BLOCK_SIZE)
+      {
+      cipher->encrypt(state);
+      position = 0;
+      }
+
+   while(length >= BLOCK_SIZE)
+      {
+      xor_buf(buffer, input, state, BLOCK_SIZE);
+      send(buffer, BLOCK_SIZE);
+
+      input += BLOCK_SIZE;
+      length -= BLOCK_SIZE;
+      cipher->encrypt(state);
+      }
+
+   xor_buf(buffer, input, state + position, length);
+   send(buffer, length);
+   position += length;
+   }
+
+}