1 files changed, 167 insertions, 0 deletions
diff --git a/src/sha1prng.cpp b/src/sha1prng.cpp
new file mode 100644
index 000000000..562b001bd
--- /dev/null
+++ b/src/sha1prng.cpp
@@ -0,0 +1,167 @@
+/*************************************************
+* SHA1PRNG Source File                           *
+* (C) 2007 FlexSecure GmbH / Manuel Hartl        *
+* (C) 2008 Jack Lloyd                            *
+*************************************************/
+
+#include <botan/sha1prng.h>
+#include <botan/lookup.h>
+#include <botan/bit_ops.h>
+#include <algorithm>
+
+namespace Botan {
+
+/*************************************************
+* Generate a buffer of random bytes              *
+*************************************************/
+void SHA1PRNG::randomize(byte result[], u32bit length) throw(PRNG_Unseeded)
+   {
+   if(!is_seeded())
+      throw PRNG_Unseeded(name());
+
+   const u32bit SHA1_BYTES = hash->OUTPUT_LENGTH;
+
+   u32bit resultIndex=0;
+   /**
+    * use ramining bytes from buffer for result
+    */
+   if(buf_pos>0)
+   {
+       u32bit remainderCountIndex=buf_pos;
+       unsigned int j = length >= (unsigned)(SHA1_BYTES - buf_pos) ? SHA1_BYTES - buf_pos : length;
+
+       for(;resultIndex < j;resultIndex++)
+       {
+           result[resultIndex] = buffer[remainderCountIndex];
+           buffer[remainderCountIndex++] = 0;
+       }
+
+       buf_pos += j;
+   }
+
+   /**
+    * fill result with fresh random bytes
+    */
+   while(resultIndex < length)
+       {
+       hash->update(state.begin(),SHA1_BYTES);
+       hash->final(buffer.begin());
+       update_state(buffer.begin());
+       int k=length-1 <= SHA1_BYTES ? length : SHA1_BYTES;
+       for(int j = 0;j < k; j++)
+       {
+           result[resultIndex++] = buffer[j];
+           buffer[j] = 0;
+       }
+       buf_pos+=k;
+       }
+   buf_pos %=SHA1_BYTES;
+   }
+
+/*************************************************
+* Refill the internal state                      *
+*************************************************/
+void SHA1PRNG::update_state(byte update[])
+   {
+   signed int i = 1;
+   bool flag2 = false;
+
+   for(u32bit k = 0; k < state.size(); k++)
+      {
+      int b1 = state[k]%256;
+      if(b1>128)
+         {
+         b1-=256;
+         }
+
+      int b2 = update[k]%256;
+      if(b2>128)
+         {
+         b2-=256;
+         }
+      int j = b1+b2+i;
+      if(j>256)
+         {
+         j-=256;
+         }
+      flag2 |= state.begin()[k] != (byte)j;
+      state.begin()[k] = (byte)j;
+      i = j >> 8;
+      }
+
+   if(!flag2)
+      {
+      state[0]++;
+      }
+   }
+
+/*************************************************
+* Add entropy to internal state                  *
+*************************************************/
+void SHA1PRNG::add_randomness(const byte data[], u32bit length)
+   {
+   prng->add_entropy(data, length);
+   MemoryVector<byte> for_rand;
+   for_rand.set(data, length);
+
+   if(prng->is_seeded())
+      {
+      prng->randomize(for_rand, length);
+      hash->clear();
+      hash->update(for_rand,length);
+      hash->final(state.begin());
+      }
+   }
+
+/*************************************************
+* Check if the RNG is seeded                     *
+*************************************************/
+bool SHA1PRNG::is_seeded() const
+   {
+   return prng->is_seeded();
+   }
+
+/*************************************************
+* Clear memory of sensitive data                 *
+*************************************************/
+void SHA1PRNG::clear() throw()
+   {
+   hash->clear();
+   prng->clear();
+   }
+
+/*************************************************
+* Return the name of this type                   *
+*************************************************/
+std::string SHA1PRNG::name() const
+   {
+   return "SHA1PRNG";
+   }
+
+/*************************************************
+* SHA1PRNG Constructor                           *
+*************************************************/
+SHA1PRNG::SHA1PRNG(RandomNumberGenerator* prng_ptr)
+   {
+   if(!prng_ptr)
+      throw Invalid_Argument("SHA1PRNG constructor: NULL prng");
+
+   hash = get_hash("SHA-1");
+   prng = prng_ptr;
+
+   buf_pos = 0;
+
+   state.grow_to(hash->OUTPUT_LENGTH);
+   buffer.grow_to(hash->OUTPUT_LENGTH);
+   }
+
+/*************************************************
+* SHA1PRNG Destructor                            *
+*************************************************/
+SHA1PRNG::~SHA1PRNG()
+   {
+   delete hash;
+   delete prng;
+   }
+
+}