1 files changed, 97 insertions, 0 deletions
diff --git a/src/stream/ofb/ofb.cpp b/src/stream/ofb/ofb.cpp
new file mode 100644
index 000000000..577f61cbf
--- /dev/null
+++ b/src/stream/ofb/ofb.cpp
@@ -0,0 +1,97 @@
+/*
+* OFB Mode
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/ofb.h>
+#include <botan/xor_buf.h>
+#include <algorithm>
+
+namespace Botan {
+
+/*
+* OFB Constructor
+*/
+OFB::OFB(BlockCipher* ciph) :
+   StreamCipher(ciph->MINIMUM_KEYLENGTH,
+                ciph->MAXIMUM_KEYLENGTH,
+                ciph->KEYLENGTH_MULTIPLE),
+   permutation(ciph)
+   {
+   position = 0;
+   buffer.create(permutation->BLOCK_SIZE);
+   }
+
+/*
+* OFB Destructor
+*/
+OFB::~OFB()
+   {
+   delete permutation;
+   }
+
+/*
+* Zeroize
+*/
+void OFB::clear() throw()
+   {
+   permutation->clear();
+   buffer.clear();
+   position = 0;
+   }
+
+/*
+* Set the key
+*/
+void OFB::key_schedule(const byte key[], u32bit key_len)
+   {
+   permutation->set_key(key, key_len);
+
+   // Set a default all-zeros IV
+   set_iv(0, 0);
+   }
+
+/*
+* Return the name of this type
+*/
+std::string OFB::name() const
+   {
+   return ("OFB(" + permutation->name() + ")");
+   }
+
+/*
+* CTR-BE Encryption/Decryption
+*/
+void OFB::cipher(const byte in[], byte out[], u32bit length)
+   {
+   while(length >= buffer.size() - position)
+      {
+      xor_buf(out, in, buffer.begin() + position, buffer.size() - position);
+      length -= (buffer.size() - position);
+      in += (buffer.size() - position);
+      out += (buffer.size() - position);
+      permutation->encrypt(buffer);
+      position = 0;
+      }
+   xor_buf(out, in, buffer.begin() + position, length);
+   position += length;
+   }
+
+/*
+* Set CTR-BE IV
+*/
+void OFB::set_iv(const byte iv[], u32bit iv_len)
+   {
+   if(!valid_iv_length(iv_len))
+      throw Invalid_IV_Length(name(), iv_len);
+
+   buffer.clear();
+   buffer.copy(0, iv, iv_len);
+
+   permutation->encrypt(buffer);
+   position = 0;
+   }
+
+}