Add Stateful_RNG

Handles fork checking for HMAC_RNG and HMAC_DRBG

AutoSeeded_RNG change - switch to HMAC_DRBG as default.

Start removing the io buffer from entropy poller.

Update default RNG poll bits to 256.

Fix McEliece test, was using wrong RNG API.

Update docs.

2 files changed, 17 insertions, 7 deletions

diff --git a/src/lib/rng/hmac_drbg/hmac_drbg.cpp b/src/lib/rng/hmac_drbg/hmac_drbg.cpp
index 201a9f39b..6fdd7daf9 100644
--- a/src/lib/rng/hmac_drbg/hmac_drbg.cpp
+++ b/src/lib/rng/hmac_drbg/hmac_drbg.cpp
@@ -10,9 +10,14 @@
 
 namespace Botan {
 
-HMAC_DRBG::HMAC_DRBG(const std::string& hmac_hash) :
-   HMAC_DRBG(hmac_hash, BOTAN_RNG_MAX_OUTPUT_BEFORE_RESEED)
-   {}
+HMAC_DRBG::HMAC_DRBG(MessageAuthenticationCode* hmac,
+                     size_t max_bytes_before_reseed) :
+   Stateful_RNG(max_bytes_before_reseed),
+   m_mac(hmac)
+   {
+   m_V.resize(m_mac->output_length());
+   clear();
+   }
 
 HMAC_DRBG::HMAC_DRBG(const std::string& hmac_hash,
                      size_t max_bytes_before_reseed) :
@@ -27,12 +32,13 @@ HMAC_DRBG::HMAC_DRBG(const std::string& hmac_hash,
       }
 
    m_V.resize(m_mac->output_length());
-
    clear();
    }
 
 void HMAC_DRBG::clear()
    {
+   Stateful_RNG::clear();
+
    for(size_t i = 0; i != m_V.size(); ++i)
       m_V[i] = 0x01;
    m_mac->set_key(std::vector<byte>(m_mac->output_length(), 0x00));
diff --git a/src/lib/rng/hmac_drbg/hmac_drbg.h b/src/lib/rng/hmac_drbg/hmac_drbg.h
index f52ae9de1..8ee598470 100644
--- a/src/lib/rng/hmac_drbg/hmac_drbg.h
+++ b/src/lib/rng/hmac_drbg/hmac_drbg.h
@@ -19,10 +19,14 @@ namespace Botan {
 class BOTAN_DLL HMAC_DRBG final : public Stateful_RNG
    {
    public:
-      HMAC_DRBG(const std::string& hmac_hash);
-
+      /**
+      * Initialize an HMAC_DRBG instance with the given hash function
+      */
       HMAC_DRBG(const std::string& hmac_hash,
-                size_t max_bytes_before_reseed);
+                size_t max_bytes_before_reseed = BOTAN_RNG_MAX_OUTPUT_BEFORE_RESEED);
+
+      HMAC_DRBG(MessageAuthenticationCode* hmac,
+                size_t max_bytes_before_reseed = BOTAN_RNG_MAX_OUTPUT_BEFORE_RESEED);
 
       std::string name() const override;