1 files changed, 62 insertions, 6 deletions
diff --git a/src/lib/rng/hmac_drbg/hmac_drbg.h b/src/lib/rng/hmac_drbg/hmac_drbg.h
index 0e294dbdb..4f96af816 100644
--- a/src/lib/rng/hmac_drbg/hmac_drbg.h
+++ b/src/lib/rng/hmac_drbg/hmac_drbg.h
@@ -8,11 +8,13 @@
 #ifndef BOTAN_HMAC_DRBG_H__
 #define BOTAN_HMAC_DRBG_H__
 
-#include <botan/rng.h>
+#include <botan/stateful_rng.h>
 #include <botan/mac.h>
 
 namespace Botan {
 
+class Entropy_Sources;
+
 /**
 * HMAC_DRBG from NIST SP800-90A
 */
@@ -20,13 +22,64 @@ class BOTAN_DLL HMAC_DRBG final : public Stateful_RNG
    {
    public:
       /**
-      * Initialize an HMAC_DRBG instance with the given hash function
+      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
+      *
+      * Automatic reseeding is disabled completely, as it as no access to
+      * any source for seed material.
+      *
+      * If a fork is detected, the RNG will be unable to reseed itself
+      * in response. In this case, an exception will be thrown rather
+      * than generating duplicated output.
+      */
+      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf);
+
+      /**
+      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
+      *
+      * @param underlying_rng is a reference to some RNG which will be used
+      * to perform the periodic reseeding
+      * @param reseed_interval specifies a limit of how many times
+      * the RNG will be called before automatic reseeding is performed.
+      */
+      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
+                RandomNumberGenerator& underlying_rng,
+                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL);
+
+      /**
+      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
+      *
+      * @param entropy_sources will be polled to perform reseeding periodically
+      * @param reseed_interval specifies a limit of how many times
+      * the RNG will be called before automatic reseeding is performed.
       */
-      HMAC_DRBG(const std::string& hmac_hash,
-                size_t max_output_before_reseed = BOTAN_RNG_DEFAULT_MAX_OUTPUT_BEFORE_RESEED);
+      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
+                Entropy_Sources& entropy_sources,
+                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL);
 
-      HMAC_DRBG(MessageAuthenticationCode* hmac,
-                size_t max_output_before_reseed = BOTAN_RNG_DEFAULT_MAX_OUTPUT_BEFORE_RESEED);
+      /**
+      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
+      *
+      * @param underlying_rng is a reference to some RNG which will be used
+      * to perform the periodic reseeding
+      * @param entropy_sources will be polled to perform reseeding periodically
+      * @param reseed_interval specifies a limit of how many times
+      * the RNG will be called before automatic reseeding is performed.
+      */
+      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
+                RandomNumberGenerator& underlying_rng,
+                Entropy_Sources& entropy_sources,
+                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL);
+
+      /**
+      * Constructor taking a string for the hash
+      */
+      HMAC_DRBG(const std::string& hmac_hash) : Stateful_RNG()
+         {
+         m_mac = MessageAuthenticationCode::create("HMAC(" + hmac_hash + ")");
+         if(!m_mac)
+            throw Algorithm_Not_Found(hmac_hash);
+         clear();
+         }
 
       std::string name() const override;
 
@@ -38,6 +91,9 @@ class BOTAN_DLL HMAC_DRBG final : public Stateful_RNG
                                 const byte input[], size_t input_len) override;
 
       void add_entropy(const byte input[], size_t input_len) override;
+
+      size_t security_level() const override;
+
    private:
       void update(const byte input[], size_t input_len);