Improve polynomial doubling code, move to util

Now does 64-bits at a time instead of 8 bits, and avoids conditional
timing channel on the XOR carry. Confirmed that at least GCC 7 and
Clang 4 on x86-64 compile the functions without conditional jumps.

Also removes CMAC as a dependency of OCB, which only needed it in
order to call CMAC::poly_double

1 files changed, 22 insertions, 0 deletions

diff --git a/src/tests/test_utils.cpp b/src/tests/test_utils.cpp
index a1e583cd8..0ca79b6e9 100644
--- a/src/tests/test_utils.cpp
+++ b/src/tests/test_utils.cpp
@@ -12,6 +12,7 @@
 #include <botan/loadstor.h>
 #include <botan/calendar.h>
 #include <botan/internal/rounding.h>
+#include <botan/internal/poly_dbl.h>
 #include <botan/charset.h>
 #include <botan/parsing.h>
 
@@ -177,6 +178,27 @@ class Utility_Function_Tests : public Text_Based_Test
 
 BOTAN_REGISTER_TEST("util", Utility_Function_Tests);
 
+class Poly_Double_Tests : public Text_Based_Test
+   {
+   public:
+      Poly_Double_Tests() : Text_Based_Test("poly_dbl.vec", "In,Out") {}
+
+      Test::Result run_one_test(const std::string&, const VarMap& vars) override
+         {
+         Test::Result result("Polynomial doubling");
+         const std::vector<uint8_t> in  = get_req_bin(vars, "In");
+         const std::vector<uint8_t> out = get_req_bin(vars, "Out");
+
+         std::vector<uint8_t> b = in;
+         Botan::poly_double_n(b.data(), b.size());
+
+         result.test_eq("Expected value", b, out);
+         return result;
+         }
+   };
+
+BOTAN_REGISTER_TEST("poly_dbl", Poly_Double_Tests);
+
 class Date_Format_Tests : public Text_Based_Test
    {
    public: