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

5 files changed, 6 insertions, 37 deletions

diff --git a/src/pubkey/blinding.cpp b/src/pubkey/blinding.cpp
index 819d0dd20..c4c0e3b6e 100644
--- a/src/pubkey/blinding.cpp
+++ b/src/pubkey/blinding.cpp
@@ -7,11 +7,6 @@
 
 #include <botan/blinding.h>
 #include <botan/numthry.h>
-#include <botan/libstate.h>
-#include <botan/hash.h>
-#include <botan/time.h>
-#include <botan/loadstor.h>
-#include <memory>
 
 namespace Botan {
 
@@ -28,28 +23,6 @@ Blinder::Blinder(const BigInt& e, const BigInt& d, const BigInt& n)
    this->d = d;
    }
 
-BigInt Blinder::choose_nonce(const BigInt& x, const BigInt& mod)
-   {
-   Algorithm_Factory& af = global_state().algorithm_factory();
-
-   std::auto_ptr<HashFunction> hash(af.make_hash_function("SHA-512"));
-
-   u64bit ns_clock = get_nanoseconds_clock();
-   for(size_t i = 0; i != sizeof(ns_clock); ++i)
-      hash->update(get_byte(i, ns_clock));
-
-   hash->update(BigInt::encode(x));
-   hash->update(BigInt::encode(mod));
-
-   u64bit timestamp = system_time();
-   for(size_t i = 0; i != sizeof(timestamp); ++i)
-      hash->update(get_byte(i, timestamp));
-
-   SecureVector<byte> r = hash->final();
-
-   return BigInt::decode(r) % mod;
-   }
-
 /*
 * Blind a number
 */
diff --git a/src/pubkey/blinding.h b/src/pubkey/blinding.h
index 3398f8c6f..03c9043dd 100644
--- a/src/pubkey/blinding.h
+++ b/src/pubkey/blinding.h
@@ -24,13 +24,6 @@ class BOTAN_DLL Blinder
 
       bool initialized() const { return reducer.initialized(); }
 
-      /**
-      * Choose a nonce to use for blinding
-      * @param x a secret seed value
-      * @param mod the modulus
-      */
-      static BigInt choose_nonce(const BigInt& x, const BigInt& mod);
-
       Blinder() {}
 
       /**
diff --git a/src/pubkey/dh/dh.cpp b/src/pubkey/dh/dh.cpp
index 1a6c6986d..f7d1838ce 100644
--- a/src/pubkey/dh/dh.cpp
+++ b/src/pubkey/dh/dh.cpp
@@ -7,6 +7,7 @@
 
 #include <botan/dh.h>
 #include <botan/numthry.h>
+#include <botan/libstate.h>
 #include <botan/internal/workfactor.h>
 
 namespace Botan {
@@ -78,7 +79,7 @@ MemoryVector<byte> DH_PrivateKey::public_value() const
 DH_KA_Operation::DH_KA_Operation(const DH_PrivateKey& dh) :
    p(dh.group_p()), powermod_x_p(dh.get_x(), p)
    {
-   BigInt k = Blinder::choose_nonce(powermod_x_p(dh.get_y()), p);
+   BigInt k(global_state().global_rng(), p.bits() - 1);
    blinder = Blinder(k, powermod_x_p(inverse_mod(k, p)), p);
    }
 
diff --git a/src/pubkey/elgamal/elgamal.cpp b/src/pubkey/elgamal/elgamal.cpp
index 3ae0f5aae..5640a4400 100644
--- a/src/pubkey/elgamal/elgamal.cpp
+++ b/src/pubkey/elgamal/elgamal.cpp
@@ -7,6 +7,7 @@
 
 #include <botan/elgamal.h>
 #include <botan/numthry.h>
+#include <botan/libstate.h>
 #include <botan/keypair.h>
 #include <botan/internal/workfactor.h>
 
@@ -118,7 +119,7 @@ ElGamal_Decryption_Operation::ElGamal_Decryption_Operation(const ElGamal_Private
    powermod_x_p = Fixed_Exponent_Power_Mod(key.get_x(), p);
    mod_p = Modular_Reducer(p);
 
-   BigInt k = Blinder::choose_nonce(powermod_x_p(key.get_y()), p);
+   BigInt k(global_state().global_rng(), p.bits() - 1);
    blinder = Blinder(k, powermod_x_p(k), p);
    }
 
diff --git a/src/pubkey/rsa/rsa.cpp b/src/pubkey/rsa/rsa.cpp
index 19ca27f40..3222b5113 100644
--- a/src/pubkey/rsa/rsa.cpp
+++ b/src/pubkey/rsa/rsa.cpp
@@ -6,6 +6,7 @@
 */
 
 #include <botan/rsa.h>
+#include <botan/libstate.h>
 #include <botan/parsing.h>
 #include <botan/numthry.h>
 #include <botan/keypair.h>
@@ -80,7 +81,7 @@ RSA_Private_Operation::RSA_Private_Operation(const RSA_PrivateKey& rsa) :
    powermod_d2_q(rsa.get_d2(), rsa.get_q()),
    mod_p(rsa.get_p())
    {
-   BigInt k = Blinder::choose_nonce(powermod_e_n(q), n);
+   BigInt k(global_state().global_rng(), n.bits() - 1);
    blinder = Blinder(powermod_e_n(k), inverse_mod(k, n), n);
    }