1 files changed, 103 insertions, 0 deletions
diff --git a/src/cipher/arc4/arc4.cpp b/src/cipher/arc4/arc4.cpp
new file mode 100644
index 000000000..238567cdc
--- /dev/null
+++ b/src/cipher/arc4/arc4.cpp
@@ -0,0 +1,103 @@
+/*************************************************
+* ARC4 Source File                               *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/arc4.h>
+#include <botan/xor_buf.h>
+#include <botan/parsing.h>
+
+namespace Botan {
+
+/*************************************************
+* Combine cipher stream with message             *
+*************************************************/
+void ARC4::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);
+      generate();
+      }
+   xor_buf(out, in, buffer.begin() + position, length);
+   position += length;
+   }
+
+/*************************************************
+* Generate cipher stream                         *
+*************************************************/
+void ARC4::generate()
+   {
+   u32bit SX, SY;
+   for(u32bit j = 0; j != buffer.size(); j += 4)
+      {
+      SX = state[X+1]; Y = (Y + SX) % 256; SY = state[Y];
+      state[X+1] = SY; state[Y] = SX;
+      buffer[j] = state[(SX + SY) % 256];
+
+      SX = state[X+2]; Y = (Y + SX) % 256; SY = state[Y];
+      state[X+2] = SY; state[Y] = SX;
+      buffer[j+1] = state[(SX + SY) % 256];
+
+      SX = state[X+3]; Y = (Y + SX) % 256; SY = state[Y];
+      state[X+3] = SY; state[Y] = SX;
+      buffer[j+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[j+3] = state[(SX + SY) % 256];
+      }
+   position = 0;
+   }
+
+/*************************************************
+* ARC4 Key Schedule                              *
+*************************************************/
+void ARC4::key(const byte key[], u32bit length)
+   {
+   clear();
+   for(u32bit j = 0; j != 256; ++j)
+      state[j] = j;
+   for(u32bit j = 0, state_index = 0; j != 256; ++j)
+      {
+      state_index = (state_index + key[j % length] + state[j]) % 256;
+      std::swap(state[j], state[state_index]);
+      }
+   for(u32bit j = 0; j <= SKIP; j += buffer.size())
+      generate();
+   position += (SKIP % buffer.size());
+   }
+
+/*************************************************
+* Return the name of this type                   *
+*************************************************/
+std::string ARC4::name() const
+   {
+   if(SKIP == 0)   return "ARC4";
+   if(SKIP == 256) return "MARK-4";
+   else            return "RC4_skip(" + to_string(SKIP) + ")";
+   }
+
+/*************************************************
+* Clear memory of sensitive data                 *
+*************************************************/
+void ARC4::clear() throw()
+   {
+   state.clear();
+   buffer.clear();
+   position = X = Y = 0;
+   }
+
+/*************************************************
+* ARC4 Constructor                               *
+*************************************************/
+ARC4::ARC4(u32bit s) : StreamCipher(1, 256), SKIP(s)
+   {
+   clear();
+   }
+
+}