There are some nasty API problems that are caused by having to pass a

PRNG everywhere. The removal of the global PRNG was generated by a
desire to remove the global library state entirely. However the real
point of this was to remove the use of globally visible _mutable_
state; of the mutable state, the PRNG is probably the least important,
and the most useful to share. And it seems unlikely that thread
contention would be a major issue in the PRNG.

Add back a global PRNG to Library_State. Use lazy initialization, so
apps that don't ever use a PRNG don't need a seeding step. Then have
AutoSeeded_RNG call that global PRNG.

Offer once again

RandomNumberGenerator& Library_State::global_rng();

which returns a reference to the global PRNG.

This RNG object serializes access to itself with a mutex.

Remove the hack known as Blinding::choose_nonce, replace with using
the global PRNG to choose a blinding nonce

4 files changed, 235 insertions, 8 deletions

diff --git a/src/libstate/global_rng.cpp b/src/libstate/global_rng.cpp
new file mode 100644
index 000000000..c18705a3a
--- /dev/null
+++ b/src/libstate/global_rng.cpp
@@ -0,0 +1,196 @@
+/*
+* Global PRNG
+* (C) 2008-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/libstate.h>
+#include <botan/mutex.h>
+
+#if defined(BOTAN_HAS_RANDPOOL)
+  #include <botan/randpool.h>
+#endif
+
+#if defined(BOTAN_HAS_HMAC_RNG)
+  #include <botan/hmac_rng.h>
+#endif
+
+#if defined(BOTAN_HAS_X931_RNG)
+  #include <botan/x931_rng.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_HIGH_RESOLUTION_TIMER)
+  #include <botan/internal/hres_timer.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
+  #include <botan/internal/dev_random.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_EGD)
+  #include <botan/internal/es_egd.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_UNIX)
+  #include <botan/internal/es_unix.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_BEOS)
+  #include <botan/internal/es_beos.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_CAPI)
+  #include <botan/internal/es_capi.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
+  #include <botan/internal/es_win32.h>
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_FTW)
+  #include <botan/internal/es_ftw.h>
+#endif
+
+namespace Botan {
+
+namespace {
+
+/**
+* Add any known entropy sources to this RNG
+*/
+void add_entropy_sources(RandomNumberGenerator* rng)
+   {
+#if defined(BOTAN_HAS_ENTROPY_SRC_HIGH_RESOLUTION_TIMER)
+   rng->add_entropy_source(new High_Resolution_Timestamp);
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
+   rng->add_entropy_source(
+      new Device_EntropySource(
+         split_on("/dev/urandom:/dev/random:/dev/srandom", ':')
+         )
+      );
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_EGD)
+   rng->add_entropy_source(
+      new EGD_EntropySource(split_on("/var/run/egd-pool:/dev/egd-pool", ':'))
+      );
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_CAPI)
+   rng->add_entropy_source(new Win32_CAPI_EntropySource);
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_FTW)
+   rng->add_entropy_source(new FTW_EntropySource("/proc"));
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
+   rng->add_entropy_source(new Win32_EntropySource);
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_BEOS)
+   rng->add_entropy_source(new BeOS_EntropySource);
+#endif
+
+#if defined(BOTAN_HAS_ENTROPY_SRC_UNIX)
+   rng->add_entropy_source(
+      new Unix_EntropySource(split_on("/bin:/sbin:/usr/bin:/usr/sbin", ':'))
+      );
+#endif
+   }
+
+class Serialized_PRNG : public RandomNumberGenerator
+   {
+   public:
+      void randomize(byte out[], u32bit len)
+         {
+         Mutex_Holder lock(mutex);
+         rng->randomize(out, len);
+         }
+
+      bool is_seeded() const
+         {
+         Mutex_Holder lock(mutex);
+         return rng->is_seeded();
+         }
+
+      void clear()
+         {
+         Mutex_Holder lock(mutex);
+         rng->clear();
+         }
+
+      std::string name() const
+         {
+         Mutex_Holder lock(mutex);
+         return rng->name();
+         }
+
+      void reseed(u32bit poll_bits)
+         {
+         Mutex_Holder lock(mutex);
+         rng->reseed(poll_bits);
+         }
+
+      void add_entropy_source(EntropySource* es)
+         {
+         Mutex_Holder lock(mutex);
+         rng->add_entropy_source(es);
+         }
+
+      void add_entropy(const byte in[], u32bit len)
+         {
+         Mutex_Holder lock(mutex);
+         rng->add_entropy(in, len);
+         }
+
+      // We do not own the mutex; Library_State does
+      Serialized_PRNG(RandomNumberGenerator* r, Mutex* m) :
+         mutex(m), rng(r) {}
+
+      ~Serialized_PRNG() { delete rng; }
+   private:
+      Mutex* mutex;
+      RandomNumberGenerator* rng;
+   };
+
+}
+
+RandomNumberGenerator* Library_State::make_global_rng(Algorithm_Factory& af,
+                                                      Mutex* mutex)
+   {
+   RandomNumberGenerator* rng = 0;
+
+#if defined(BOTAN_HAS_HMAC_RNG)
+
+   rng = new HMAC_RNG(af.make_mac("HMAC(SHA-512)"),
+                      af.make_mac("HMAC(SHA-256)"));
+
+#elif defined(BOTAN_HAS_RANDPOOL) && defined(BOTAN_HAS_AES)
+
+   rng = new Randpool(af.make_block_cipher("AES-256"),
+                      af.make_mac("HMAC(SHA-256)"));
+
+#endif
+
+   if(!rng)
+      throw Internal_Error("No usable RNG found enabled in build");
+
+   /* If X9.31 is available, use it to wrap the other RNG as a failsafe */
+#if defined(BOTAN_HAS_X931_RNG) && defined(BOTAN_HAS_AES)
+
+   rng = new ANSI_X931_RNG(af.make_block_cipher("AES-256"), rng);
+
+#endif
+
+   add_entropy_sources(rng);
+
+   rng->reseed(256);
+
+   return new Serialized_PRNG(rng, mutex);
+   }
+
+}
diff --git a/src/libstate/info.txt b/src/libstate/info.txt
index 3992d25bd..905675109 100644
--- a/src/libstate/info.txt
+++ b/src/libstate/info.txt
@@ -14,6 +14,7 @@ scan_name.h
 <source>
 get_enc.cpp
 init.cpp
+global_rng.cpp
 libstate.cpp
 lookup.cpp
 policy.cpp
@@ -29,6 +30,7 @@ def_engine
 engine
 filters
 hash
+hmac
 kdf
 mac
 mode_pad
@@ -38,6 +40,7 @@ pk_pad
 pubkey
 rng
 s2k
+sha2
 stream
 system_alloc
 </requires>
diff --git a/src/libstate/libstate.cpp b/src/libstate/libstate.cpp
index 7706cef28..c62bd08db 100644
--- a/src/libstate/libstate.cpp
+++ b/src/libstate/libstate.cpp
@@ -214,8 +214,8 @@ std::string Library_State::deref_alias(const std::string& key) const
    return result;
    }
 
-/**
-Return a reference to the Algorithm_Factory
+/*
+* Return a reference to the Algorithm_Factory
 */
 Algorithm_Factory& Library_State::algorithm_factory() const
    {
@@ -225,6 +225,20 @@ Algorithm_Factory& Library_State::algorithm_factory() const
    }
 
 /*
+* Return a reference to the global PRNG
+*/
+RandomNumberGenerator& Library_State::global_rng()
+   {
+   Mutex_Holder lock(global_rng_lock);
+
+   if(!global_rng_ptr)
+      global_rng_ptr = make_global_rng(algorithm_factory(),
+                                       global_rng_lock);
+
+   return *global_rng_ptr;
+   }
+
+/*
 * Load a set of modules
 */
 void Library_State::initialize(bool thread_safe)
@@ -249,17 +263,20 @@ void Library_State::initialize(bool thread_safe)
 #endif
       }
 
-   allocator_lock = mutex_factory->make();
-   config_lock = mutex_factory->make();
+   allocator_lock = get_mutex();
+   config_lock = get_mutex();
+   global_rng_lock = get_mutex();
+
+   global_rng_ptr = 0;
 
    cached_default_allocator = 0;
    default_allocator_name = has_mlock() ? "locking" : "malloc";
 
    add_allocator(new Malloc_Allocator);
-   add_allocator(new Locking_Allocator(mutex_factory->make()));
+   add_allocator(new Locking_Allocator(get_mutex()));
 
 #if defined(BOTAN_HAS_ALLOC_MMAP)
-   add_allocator(new MemoryMapping_Allocator(mutex_factory->make()));
+   add_allocator(new MemoryMapping_Allocator(get_mutex()));
 #endif
 
    load_default_config();
diff --git a/src/libstate/libstate.h b/src/libstate/libstate.h
index ade17c17e..4674eca88 100644
--- a/src/libstate/libstate.h
+++ b/src/libstate/libstate.h
@@ -8,9 +8,9 @@
 #ifndef BOTAN_LIB_STATE_H__
 #define BOTAN_LIB_STATE_H__
 
-#include <botan/types.h>
 #include <botan/allocate.h>
 #include <botan/algo_factory.h>
+#include <botan/rng.h>
 
 #include <string>
 #include <vector>
@@ -37,6 +37,11 @@ class BOTAN_DLL Library_State
       Algorithm_Factory& algorithm_factory() const;
 
       /**
+      * @return the global RandomNumberGenerator
+      */
+      RandomNumberGenerator& global_rng();
+
+      /**
       * @param name the name of the allocator
       * @return allocator matching this name, or NULL
       */
@@ -107,6 +112,9 @@ class BOTAN_DLL Library_State
       */
       Mutex* get_mutex() const;
    private:
+      static RandomNumberGenerator* make_global_rng(Algorithm_Factory& af,
+                                                    Mutex* mutex);
+
       void load_default_config();
 
       Library_State(const Library_State&) {}
@@ -114,8 +122,11 @@ class BOTAN_DLL Library_State
 
       class Mutex_Factory* mutex_factory;
 
-      std::map<std::string, std::string> config;
+      Mutex* global_rng_lock;
+      RandomNumberGenerator* global_rng_ptr;
+
       Mutex* config_lock;
+      std::map<std::string, std::string> config;
 
       Mutex* allocator_lock;
       std::string default_allocator_name;