Externalize the state of a RFC 6979 nonce computation.

This lets you amortize quite a few memory allocations (RNG, various
BigInts, etc) over many nonce generations.

Change generate_rfc6979_nonce to just instantiate one of these states,
call the function once, and return. This doesn't have any additional
overhead versus the previous implementation of this function.

Fix HMAC_DRBG to correctly reset its state to its starting position
when you call clear() on it.

1 files changed, 31 insertions, 3 deletions

diff --git a/src/tests/test_rfc6979.cpp b/src/tests/test_rfc6979.cpp
index 8ecc04fa3..4f286b96e 100644
--- a/src/tests/test_rfc6979.cpp
+++ b/src/tests/test_rfc6979.cpp
@@ -22,10 +22,12 @@ size_t rfc6979_testcase(const std::string& q_str,
                         const std::string& hash,
                         size_t testcase)
    {
-   using namespace Botan;
+   size_t fails = 0;
 
 #if defined(BOTAN_HAS_RFC6979_GENERATOR)
 
+   using namespace Botan;
+
    const BigInt q(q_str);
    const BigInt x(x_str);
    const BigInt h(h_str);
@@ -37,12 +39,38 @@ size_t rfc6979_testcase(const std::string& q_str,
       {
       std::cout << "RFC 6979 test #" << testcase << " failed; generated k="
                 << std::hex << gen_k << "\n";
-      return 1;
+      ++fails;
+      }
+
+   RFC6979_Nonce_Generator gen(hash, q, x);
+
+   const BigInt gen_0 = gen.nonce_for(h);
+   if(gen_0 != exp_k)
+      {
+      std::cout << "RFC 6979 test #" << testcase << " failed; generated k="
+                << std::hex << gen_k << " (gen_0)\n";
+      ++fails;
+      }
+
+   const BigInt gen_1 = gen.nonce_for(h+1);
+   if(gen_1 == exp_k)
+      {
+      std::cout << "RFC 6979 test #" << testcase << " failed; generated k="
+                << std::hex << gen_1 << " (gen_1)\n";
+      ++fails;
+      }
+
+   const BigInt gen_2 = gen.nonce_for(h);
+   if(gen_2 != exp_k)
+      {
+      std::cout << "RFC 6979 test #" << testcase << " failed; generated k="
+                << std::hex << gen_2 << " (gen_2)\n";
+      ++fails;
       }
 
 #endif
 
-   return 0;
+   return fails;
    }
 
 }