Similiar treatment for OFB which is also just a plain stream cipher

3 files changed, 160 insertions, 0 deletions

diff --git a/src/stream/ofb/info.txt b/src/stream/ofb/info.txt
new file mode 100644
index 000000000..444fe0ffe
--- /dev/null
+++ b/src/stream/ofb/info.txt
@@ -0,0 +1,15 @@
+realname "OFB block cipher mode"
+
+define OFB
+
+load_on auto
+
+<add>
+ofb.cpp
+ofb.h
+</add>
+
+<requires>
+block
+stream
+</requires>
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;
+   }
+
+}
diff --git a/src/stream/ofb/ofb.h b/src/stream/ofb/ofb.h
new file mode 100644
index 000000000..5cd48716b
--- /dev/null
+++ b/src/stream/ofb/ofb.h
@@ -0,0 +1,48 @@
+/*
+* OFB Mode
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_OUTPUT_FEEDBACK_MODE_H__
+#define BOTAN_OUTPUT_FEEDBACK_MODE_H__
+
+#include <botan/stream_cipher.h>
+#include <botan/block_cipher.h>
+
+namespace Botan {
+
+/*
+* OFB Mode
+*/
+class BOTAN_DLL OFB : public StreamCipher
+   {
+   public:
+      void cipher(const byte in[], byte out[], u32bit length);
+
+      void set_iv(const byte iv[], u32bit iv_len);
+
+      bool valid_iv_length(u32bit iv_len) const
+         { return (iv_len <= permutation->BLOCK_SIZE); }
+
+      std::string name() const;
+
+      OFB* clone() const
+         { return new OFB(permutation->clone()); }
+
+      void clear() throw();
+
+      OFB(BlockCipher*);
+      ~OFB();
+   private:
+      void key_schedule(const byte key[], u32bit key_len);
+
+      BlockCipher* permutation;
+      SecureVector<byte> buffer;
+      u32bit position;
+   };
+
+}
+
+#endif