1 files changed, 152 insertions, 0 deletions
diff --git a/modules/mac/cmac/cmac.cpp b/modules/mac/cmac/cmac.cpp
new file mode 100644
index 000000000..5a99f93b1
--- /dev/null
+++ b/modules/mac/cmac/cmac.cpp
@@ -0,0 +1,152 @@
+/*************************************************
+* CMAC Source File                               *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/cmac.h>
+#include <botan/lookup.h>
+#include <botan/xor_buf.h>
+
+namespace Botan {
+
+/*************************************************
+* Perform CMAC's multiplication in GF(2^n)       *
+*************************************************/
+SecureVector<byte> CMAC::poly_double(const MemoryRegion<byte>& in,
+                                     byte polynomial)
+   {
+   const bool do_xor = (in[0] & 0x80) ? true : false;
+
+   SecureVector<byte> out = in;
+
+   byte carry = 0;
+   for(u32bit j = out.size(); j != 0; --j)
+      {
+      byte temp = out[j-1];
+      out[j-1] = (temp << 1) | carry;
+      carry = (temp >> 7);
+      }
+
+   if(do_xor)
+      out[out.size()-1] ^= polynomial;
+
+   return out;
+   }
+
+/*************************************************
+* Update an CMAC Calculation                     *
+*************************************************/
+void CMAC::add_data(const byte input[], u32bit length)
+   {
+   buffer.copy(position, input, length);
+   if(position + length > OUTPUT_LENGTH)
+      {
+      xor_buf(state, buffer, OUTPUT_LENGTH);
+      e->encrypt(state);
+      input += (OUTPUT_LENGTH - position);
+      length -= (OUTPUT_LENGTH - position);
+      while(length > OUTPUT_LENGTH)
+         {
+         xor_buf(state, input, OUTPUT_LENGTH);
+         e->encrypt(state);
+         input += OUTPUT_LENGTH;
+         length -= OUTPUT_LENGTH;
+         }
+      buffer.copy(input, length);
+      position = 0;
+      }
+   position += length;
+   }
+
+/*************************************************
+* Finalize an CMAC Calculation                   *
+*************************************************/
+void CMAC::final_result(byte mac[])
+   {
+   xor_buf(state, buffer, position);
+
+   if(position == OUTPUT_LENGTH)
+      {
+      xor_buf(state, B, OUTPUT_LENGTH);
+      }
+   else
+      {
+      state[position] ^= 0x80;
+      xor_buf(state, P, OUTPUT_LENGTH);
+      }
+
+   e->encrypt(state);
+
+   for(u32bit j = 0; j != OUTPUT_LENGTH; ++j)
+      mac[j] = state[j];
+
+   state.clear();
+   buffer.clear();
+   position = 0;
+   }
+
+/*************************************************
+* CMAC Key Schedule                              *
+*************************************************/
+void CMAC::key(const byte key[], u32bit length)
+   {
+   clear();
+   e->set_key(key, length);
+   e->encrypt(B);
+   B = poly_double(B, polynomial);
+   P = poly_double(B, polynomial);
+   }
+
+/*************************************************
+* Clear memory of sensitive data                 *
+*************************************************/
+void CMAC::clear() throw()
+   {
+   e->clear();
+   state.clear();
+   buffer.clear();
+   B.clear();
+   P.clear();
+   position = 0;
+   }
+
+/*************************************************
+* Return the name of this type                   *
+*************************************************/
+std::string CMAC::name() const
+   {
+   return "CMAC(" + e->name() + ")";
+   }
+
+/*************************************************
+* Return a clone of this object                  *
+*************************************************/
+MessageAuthenticationCode* CMAC::clone() const
+   {
+   return new CMAC(e->name());
+   }
+
+/*************************************************
+* CMAC Constructor                               *
+*************************************************/
+CMAC::CMAC(const std::string& bc_name) :
+   MessageAuthenticationCode(block_size_of(bc_name),
+                             min_keylength_of(bc_name),
+                             max_keylength_of(bc_name),
+                             keylength_multiple_of(bc_name))
+   {
+   e = get_block_cipher(bc_name);
+
+   if(e->BLOCK_SIZE == 16)     polynomial = 0x87;
+   else if(e->BLOCK_SIZE == 8) polynomial = 0x1B;
+   else
+      throw Invalid_Argument("CMAC cannot use the cipher " + e->name());
+
+   state.create(OUTPUT_LENGTH);
+   buffer.create(OUTPUT_LENGTH);
+   B.create(OUTPUT_LENGTH);
+   P.create(OUTPUT_LENGTH);
+   position = 0;
+   }
+
+}