Change unix_procs entropy source to be a plain EntropySource instead of

a Buffered_EntropySource. Data used in the poll is directly accumulated
into the output buffer using XOR, wrapping around as needed. The
implementation uses xor_into_buf from xor_buf.h

This is simpler and more convincingly secure than the method used
by Buffered_EntropySource. In particular the collected data is persisted
in the buffer there much longer than needed. It is also much harder for
entropy sources to signal errors or a failure to collected data using
Buffered_EntropySource. And, with the simple xor_into_buf function, it
is actually quite easy to remove without major changes.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/entropy/unix_procs/es_unix.h b/src/entropy/unix_procs/es_unix.h
index 907ebbc3a..f4af255ca 100644
--- a/src/entropy/unix_procs/es_unix.h
+++ b/src/entropy/unix_procs/es_unix.h
@@ -6,7 +6,7 @@
 #ifndef BOTAN_ENTROPY_SRC_UNIX_H__
 #define BOTAN_ENTROPY_SRC_UNIX_H__
 
-#include <botan/buf_es.h>
+#include <botan/entropy_src.h>
 #include <botan/unix_cmd.h>
 #include <vector>
 
@@ -15,7 +15,7 @@ namespace Botan {
 /*************************************************
 * Unix Entropy Source                            *
 *************************************************/
-class BOTAN_DLL Unix_EntropySource : public Buffered_EntropySource
+class BOTAN_DLL Unix_EntropySource : public EntropySource
    {
    public:
       std::string name() const { return "Unix Entropy Source"; }
@@ -25,8 +25,8 @@ class BOTAN_DLL Unix_EntropySource : public Buffered_EntropySource
    private:
       static void add_default_sources(std::vector<Unix_Program>&);
 
-      void do_fast_poll();
-      void do_slow_poll();
+      u32bit fast_poll(byte buf[], u32bit length);
+      u32bit slow_poll(byte buf[], u32bit length);
 
       const std::vector<std::string> PATH;
       std::vector<Unix_Program> sources;