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.

1 files changed, 0 insertions, 80 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);
-   }
-
-}