Drop use of entropy estimation in Randpool for the same reason as HMAC_RNG.

As with HMAC_RNG, instead assume one bit of conditional entropy per byte
of polled material. Since they are no longer used, drop the entropy
estimation routines entirely.

3 files changed, 0 insertions, 130 deletions

diff --git a/src/utils/entropy.cpp b/src/utils/entropy.cpp
deleted file mode 100644
index 1562eb0d2..000000000
--- a/src/utils/entropy.cpp
+++ /dev/null
@@ -1,80 +0,0 @@
-/*************************************************
-* Entropy_Estimator Source File                  *
-* (C) 2008 Jack Lloyd                            *
-*************************************************/
-
-#include <botan/entropy.h>
-#include <botan/bit_ops.h>
-
-namespace Botan {
-
-/**
-Update the estimate
-*/
-void Entropy_Estimator::update(const byte buffer[], u32bit length,
-                               u32bit upper_limit)
-   {
-   u32bit this_buf_estimate = 0;
-
-   /*
-   This is pretty naive
-   */
-   for(u32bit j = 0; j != length; ++j)
-      {
-      byte delta = last ^ buffer[j];
-      last = buffer[j];
-
-      byte delta2 = delta ^ last_delta;
-      last_delta = delta;
-
-      byte delta3 = delta2 ^ last_delta2;
-      last_delta2 = delta2;
-
-      byte min_delta = delta;
-      if(min_delta > delta2) min_delta = delta2;
-      if(min_delta > delta3) min_delta = delta3;
-
-      this_buf_estimate += hamming_weight(min_delta);
-      }
-
-   this_buf_estimate /= 2;
-
-   if(upper_limit)
-      estimate += std::min(upper_limit, this_buf_estimate);
-   else
-      estimate += this_buf_estimate;
-   }
-
-/*************************************************
-* Estimate the entropy of the buffer             *
-*************************************************/
-u32bit entropy_estimate(const byte buffer[], u32bit length)
-   {
-   if(length <= 4)
-      return 0;
-
-   u32bit estimate = 0;
-   byte last = 0, last_delta = 0, last_delta2 = 0;
-
-   for(u32bit j = 0; j != length; ++j)
-      {
-      byte delta = last ^ buffer[j];
-      last = buffer[j];
-
-      byte delta2 = delta ^ last_delta;
-      last_delta = delta;
-
-      byte delta3 = delta2 ^ last_delta2;
-      last_delta2 = delta2;
-
-      byte min_delta = delta;
-      if(min_delta > delta2) min_delta = delta2;
-      if(min_delta > delta3) min_delta = delta3;
-
-      estimate += hamming_weight(min_delta);
-      }
-
-   return (estimate / 2);
-   }
-
-}
diff --git a/src/utils/entropy.h b/src/utils/entropy.h
deleted file mode 100644
index 24d2fbdbf..000000000
--- a/src/utils/entropy.h
+++ /dev/null
@@ -1,48 +0,0 @@
-/*************************************************
-* Entropy_Estimator Header File                  *
-* (C) 2008 Jack Lloyd                            *
-*************************************************/
-
-#ifndef BOTAN_ENTROPY_ESTIMATOR_H__
-#define BOTAN_ENTROPY_ESTIMATOR_H__
-
-#include <botan/types.h>
-#include <algorithm>
-
-namespace Botan {
-
-/**
-Naive Entropy Estimation using first, second, and third order deltas
-
-@todo It would be nice to extend this to test using zlib or bzip2 if
-those modules are compiled in to the library
-*/
-class BOTAN_DLL Entropy_Estimator
-   {
-   public:
-      Entropy_Estimator()
-         { last = last_delta = last_delta2 = 0; estimate = 0; }
-
-      /**
-      Return the current estimate
-      */
-      u32bit value() const { return estimate; }
-
-      /**
-      Set an upper bound on the estimate so far
-      */
-      void set_upper_bound(u32bit upper_limit)
-         { estimate = std::min(estimate, upper_limit); }
-
-      /**
-      Add more entropy data to the current estimation
-      */
-      void update(const byte buffer[], u32bit length, u32bit upper_limit = 0);
-   private:
-      u32bit estimate;
-      byte last, last_delta, last_delta2;
-   };
-
-}
-
-#endif
diff --git a/src/utils/info.txt b/src/utils/info.txt
index 99d589d8c..ffc19c852 100644
--- a/src/utils/info.txt
+++ b/src/utils/info.txt
@@ -22,8 +22,6 @@ data_src.cpp
 data_src.h
 datastor.cpp
 datastor.h
-entropy.cpp
-entropy.h
 exceptn.cpp
 exceptn.h
 loadstor.h