1 files changed, 146 insertions, 0 deletions
diff --git a/lib/rng/x931_rng/x931_rng.cpp b/lib/rng/x931_rng/x931_rng.cpp
new file mode 100644
index 000000000..b36f87106
--- /dev/null
+++ b/lib/rng/x931_rng/x931_rng.cpp
@@ -0,0 +1,146 @@
+/*
+* ANSI X9.31 RNG
+* (C) 1999-2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/x931_rng.h>
+#include <botan/internal/xor_buf.h>
+#include <algorithm>
+
+namespace Botan {
+
+/*
+* Generate a buffer of random bytes
+*/
+void ANSI_X931_RNG::randomize(byte out[], size_t length)
+   {
+   if(!is_seeded())
+      throw PRNG_Unseeded(name());
+
+   while(length)
+      {
+      if(position == R.size())
+         update_buffer();
+
+      const size_t copied = std::min<size_t>(length, R.size() - position);
+
+      copy_mem(out, &R[position], copied);
+      out += copied;
+      length -= copied;
+      position += copied;
+      }
+   }
+
+/*
+* Refill the internal state
+*/
+void ANSI_X931_RNG::update_buffer()
+   {
+   const size_t BLOCK_SIZE = cipher->block_size();
+
+   secure_vector<byte> DT = prng->random_vec(BLOCK_SIZE);
+   cipher->encrypt(DT);
+
+   xor_buf(&R[0], &V[0], &DT[0], BLOCK_SIZE);
+   cipher->encrypt(R);
+
+   xor_buf(&V[0], &R[0], &DT[0], BLOCK_SIZE);
+   cipher->encrypt(V);
+
+   position = 0;
+   }
+
+/*
+* Reset V and the cipher key with new values
+*/
+void ANSI_X931_RNG::rekey()
+   {
+   const size_t BLOCK_SIZE = cipher->block_size();
+
+   if(prng->is_seeded())
+      {
+      cipher->set_key(prng->random_vec(cipher->maximum_keylength()));
+
+      if(V.size() != BLOCK_SIZE)
+         V.resize(BLOCK_SIZE);
+      prng->randomize(&V[0], V.size());
+
+      update_buffer();
+      }
+   }
+
+/*
+* Reseed the internal state
+*/
+void ANSI_X931_RNG::reseed(size_t poll_bits)
+   {
+   prng->reseed(poll_bits);
+   rekey();
+   }
+
+/*
+* Add some entropy to the underlying PRNG
+*/
+void ANSI_X931_RNG::add_entropy(const byte input[], size_t length)
+   {
+   prng->add_entropy(input, length);
+   rekey();
+   }
+
+/*
+* Check if the the PRNG is seeded
+*/
+bool ANSI_X931_RNG::is_seeded() const
+   {
+   return (V.size() > 0);
+   }
+
+/*
+* Clear memory of sensitive data
+*/
+void ANSI_X931_RNG::clear()
+   {
+   cipher->clear();
+   prng->clear();
+   zeroise(R);
+   V.clear();
+
+   position = 0;
+   }
+
+/*
+* Return the name of this type
+*/
+std::string ANSI_X931_RNG::name() const
+   {
+   return "X9.31(" + cipher->name() + ")";
+   }
+
+/*
+* ANSI X931 RNG Constructor
+*/
+ANSI_X931_RNG::ANSI_X931_RNG(BlockCipher* cipher_in,
+                             RandomNumberGenerator* prng_in)
+   {
+   if(!prng_in || !cipher_in)
+      throw Invalid_Argument("ANSI_X931_RNG constructor: NULL arguments");
+
+   cipher = cipher_in;
+   prng = prng_in;
+
+   R.resize(cipher->block_size());
+   position = 0;
+   }
+
+/*
+* ANSI X931 RNG Destructor
+*/
+ANSI_X931_RNG::~ANSI_X931_RNG()
+   {
+   delete cipher;
+   delete prng;
+   }
+
+}