Add power analysis countermeasures for ECC point multiplications.

The plain PointGFp operator* now uses Montgomery ladder exclusively.

Adds a blinded point multiply algorithm which uses exponent and point
randomization, as well as a Montgomery ladder technique that takes a
random walk of the possible addition chains for k.

1 files changed, 24 insertions, 6 deletions

diff --git a/src/lib/rng/rng.h b/src/lib/rng/rng.h
index b1f78f75d..6ee67f66f 100644
--- a/src/lib/rng/rng.h
+++ b/src/lib/rng/rng.h
@@ -47,17 +47,35 @@ class BOTAN_DLL RandomNumberGenerator
          }
 
       /**
-      * Return a random byte
-      * @return random byte
+      * Only usable with POD types, only useful with integers
+      * get_random<u64bit>()
       */
-      byte next_byte()
+      template<typename T> T get_random()
          {
-         byte out;
-         this->randomize(&out, 1);
-         return out;
+         T r;
+         this->randomize(reinterpret_cast<byte*>(&r), sizeof(r));
+         return r;
          }
 
       /**
+      * Return a value in range [0,2^bits)
+      */
+      u64bit gen_mask(size_t bits)
+         {
+         if(bits == 0 || bits > 64)
+            throw std::invalid_argument("RandomNumberGenerator::gen_mask invalid argument");
+
+         const u64bit mask = ((1 << bits) - 1);
+         return this->get_random<u64bit>() & mask;
+         }
+
+      /**
+      * Return a random byte
+      * @return random byte
+      */
+      byte next_byte() { return get_random<byte>(); }
+
+      /**
       * Check whether this RNG is seeded.
       * @return true if this RNG was already seeded, false otherwise.
       */