1 files changed, 109 insertions, 0 deletions
diff --git a/lib/stream/rc4/rc4.cpp b/lib/stream/rc4/rc4.cpp
new file mode 100644
index 000000000..df6976235
--- /dev/null
+++ b/lib/stream/rc4/rc4.cpp
@@ -0,0 +1,109 @@
+/*
+* RC4
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/rc4.h>
+#include <botan/internal/xor_buf.h>
+#include <botan/internal/rounding.h>
+
+namespace Botan {
+
+/*
+* Combine cipher stream with message
+*/
+void RC4::cipher(const byte in[], byte out[], size_t length)
+   {
+   while(length >= buffer.size() - position)
+      {
+      xor_buf(out, in, &buffer[position], buffer.size() - position);
+      length -= (buffer.size() - position);
+      in += (buffer.size() - position);
+      out += (buffer.size() - position);
+      generate();
+      }
+   xor_buf(out, in, &buffer[position], length);
+   position += length;
+   }
+
+/*
+* Generate cipher stream
+*/
+void RC4::generate()
+   {
+   byte SX, SY;
+   for(size_t i = 0; i != buffer.size(); i += 4)
+      {
+      SX = state[X+1]; Y = (Y + SX) % 256; SY = state[Y];
+      state[X+1] = SY; state[Y] = SX;
+      buffer[i] = state[(SX + SY) % 256];
+
+      SX = state[X+2]; Y = (Y + SX) % 256; SY = state[Y];
+      state[X+2] = SY; state[Y] = SX;
+      buffer[i+1] = state[(SX + SY) % 256];
+
+      SX = state[X+3]; Y = (Y + SX) % 256; SY = state[Y];
+      state[X+3] = SY; state[Y] = SX;
+      buffer[i+2] = state[(SX + SY) % 256];
+
+      X = (X + 4) % 256;
+      SX = state[X]; Y = (Y + SX) % 256; SY = state[Y];
+      state[X] = SY; state[Y] = SX;
+      buffer[i+3] = state[(SX + SY) % 256];
+      }
+   position = 0;
+   }
+
+/*
+* RC4 Key Schedule
+*/
+void RC4::key_schedule(const byte key[], size_t length)
+   {
+   state.resize(256);
+   buffer.resize(round_up<size_t>(DEFAULT_BUFFERSIZE, 4));
+
+   position = X = Y = 0;
+
+   for(size_t i = 0; i != 256; ++i)
+      state[i] = static_cast<byte>(i);
+
+   for(size_t i = 0, state_index = 0; i != 256; ++i)
+      {
+      state_index = (state_index + key[i % length] + state[i]) % 256;
+      std::swap(state[i], state[state_index]);
+      }
+
+   for(size_t i = 0; i <= SKIP; i += buffer.size())
+      generate();
+
+   position += (SKIP % buffer.size());
+   }
+
+/*
+* Return the name of this type
+*/
+std::string RC4::name() const
+   {
+   if(SKIP == 0)   return "RC4";
+   if(SKIP == 256) return "MARK-4";
+   else            return "RC4_skip(" + std::to_string(SKIP) + ")";
+   }
+
+/*
+* Clear memory of sensitive data
+*/
+void RC4::clear()
+   {
+   zap(state);
+   zap(buffer);
+   position = X = Y = 0;
+   }
+
+/*
+* RC4 Constructor
+*/
+RC4::RC4(size_t s) : SKIP(s) {}
+
+}