1 files changed, 141 insertions, 0 deletions
diff --git a/src/lib/entropy/entropy_src.h b/src/lib/entropy/entropy_src.h
new file mode 100644
index 000000000..552eca9de
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+++ b/src/lib/entropy/entropy_src.h
@@ -0,0 +1,141 @@
+/*
+* EntropySource
+* (C) 2008-2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_ENTROPY_SOURCE_BASE_H__
+#define BOTAN_ENTROPY_SOURCE_BASE_H__
+
+#include <botan/buf_comp.h>
+#include <string>
+
+namespace Botan {
+
+/**
+* Class used to accumulate the poll results of EntropySources
+*/
+class BOTAN_DLL Entropy_Accumulator
+   {
+   public:
+      /**
+      * Initialize an Entropy_Accumulator
+      * @param goal is how many bits we would like to collect
+      */
+      Entropy_Accumulator(size_t goal) :
+         entropy_goal(goal), collected_bits(0) {}
+
+      virtual ~Entropy_Accumulator() {}
+
+      /**
+      * Get a cached I/O buffer (purely for minimizing allocation
+      * overhead to polls)
+      *
+      * @param size requested size for the I/O buffer
+      * @return cached I/O buffer for repeated polls
+      */
+      secure_vector<byte>& get_io_buffer(size_t size)
+         { io_buffer.resize(size); return io_buffer; }
+
+      /**
+      * @return number of bits collected so far
+      */
+      size_t bits_collected() const
+         { return static_cast<size_t>(collected_bits); }
+
+      /**
+      * @return if our polling goal has been achieved
+      */
+      bool polling_goal_achieved() const
+         { return (collected_bits >= entropy_goal); }
+
+      /**
+      * @return how many bits we need to reach our polling goal
+      */
+      size_t desired_remaining_bits() const
+         {
+         if(collected_bits >= entropy_goal)
+            return 0;
+         return static_cast<size_t>(entropy_goal - collected_bits);
+         }
+
+      /**
+      * Add entropy to the accumulator
+      * @param bytes the input bytes
+      * @param length specifies how many bytes the input is
+      * @param entropy_bits_per_byte is a best guess at how much
+      * entropy per byte is in this input
+      */
+      void add(const void* bytes, size_t length, double entropy_bits_per_byte)
+         {
+         add_bytes(reinterpret_cast<const byte*>(bytes), length);
+         collected_bits += entropy_bits_per_byte * length;
+         }
+
+      /**
+      * Add entropy to the accumulator
+      * @param v is some value
+      * @param entropy_bits_per_byte is a best guess at how much
+      * entropy per byte is in this input
+      */
+      template<typename T>
+      void add(const T& v, double entropy_bits_per_byte)
+         {
+         add(&v, sizeof(T), entropy_bits_per_byte);
+         }
+   private:
+      virtual void add_bytes(const byte bytes[], size_t length) = 0;
+
+      secure_vector<byte> io_buffer;
+      size_t entropy_goal;
+      double collected_bits;
+   };
+
+/**
+* Entropy accumulator that puts the input into a Buffered_Computation
+*/
+class BOTAN_DLL Entropy_Accumulator_BufferedComputation :
+   public Entropy_Accumulator
+   {
+   public:
+      /**
+      * @param sink the hash or MAC we are feeding the poll data into
+      * @param goal is how many bits we want to collect in this poll
+      */
+      Entropy_Accumulator_BufferedComputation(Buffered_Computation& sink,
+                                              size_t goal) :
+         Entropy_Accumulator(goal), entropy_sink(sink) {}
+
+   private:
+      void add_bytes(const byte bytes[], size_t length) override
+         {
+         entropy_sink.update(bytes, length);
+         }
+
+      Buffered_Computation& entropy_sink;
+   };
+
+/**
+* Abstract interface to a source of entropy
+*/
+class BOTAN_DLL EntropySource
+   {
+   public:
+      /**
+      * @return name identifying this entropy source
+      */
+      virtual std::string name() const = 0;
+
+      /**
+      * Perform an entropy gathering poll
+      * @param accum is an accumulator object that will be given entropy
+      */
+      virtual void poll(Entropy_Accumulator& accum) = 0;
+
+      virtual ~EntropySource() {}
+   };
+
+}
+
+#endif