1 files changed, 83 insertions, 0 deletions
diff --git a/src/lib/utils/poly_dbl/poly_dbl.cpp b/src/lib/utils/poly_dbl/poly_dbl.cpp
new file mode 100644
index 000000000..2b989db57
--- /dev/null
+++ b/src/lib/utils/poly_dbl/poly_dbl.cpp
@@ -0,0 +1,83 @@
+/*
+* (C) 2017 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/internal/poly_dbl.h>
+#include <botan/loadstor.h>
+#include <botan/exceptn.h>
+
+namespace Botan {
+
+namespace {
+
+template<size_t LIMBS, uint64_t POLY>
+void poly_double(uint8_t out[], const uint8_t in[])
+   {
+   uint64_t W[LIMBS];
+   load_be(W, in, LIMBS);
+
+   const uint64_t carry = POLY * (W[0] >> 63);
+   for(size_t i = 0; i != LIMBS - 1; ++i)
+      W[i] = (W[i] << 1) ^ (W[i+1] >> 63);
+   W[LIMBS-1] = (W[LIMBS-1] << 1) ^ carry;
+
+   copy_out_be(out, LIMBS*8, W);
+   }
+
+template<size_t LIMBS, uint64_t POLY>
+void poly_double_le(uint8_t out[], const uint8_t in[])
+   {
+   uint64_t W[LIMBS];
+   load_le(W, in, LIMBS);
+
+   const uint64_t carry = POLY * (W[LIMBS-1] >> 63);
+   for(size_t i = 0; i != LIMBS - 1; ++i)
+      W[LIMBS-1-i] = (W[LIMBS-1-i] << 1) ^ (W[LIMBS-2-i] >> 63);
+   W[0] = (W[0] << 1) ^ carry;
+
+   copy_out_le(out, LIMBS*8, W);
+   }
+
+}
+
+void poly_double_n(uint8_t out[], const uint8_t in[], size_t n)
+   {
+   switch(n)
+      {
+      case 8:
+         return poly_double<1, 0x1B>(out, in);
+      case 16:
+         return poly_double<2, 0x87>(out, in);
+      case 24:
+         return poly_double<3, 0x87>(out, in);
+      case 32:
+         return poly_double<4, 0x425>(out, in);
+      case 64:
+         return poly_double<8, 0x125>(out, in);
+      default:
+         throw Invalid_Argument("Unsupported size for poly_double_n");
+      }
+   }
+
+void poly_double_n_le(uint8_t out[], const uint8_t in[], size_t n)
+   {
+   switch(n)
+      {
+      case 8:
+         return poly_double_le<1, 0x1B>(out, in);
+      case 16:
+         return poly_double_le<2, 0x87>(out, in);
+      case 24:
+         return poly_double_le<3, 0x87>(out, in);
+      case 32:
+         return poly_double_le<4, 0x425>(out, in);
+      case 64:
+         return poly_double_le<8, 0x125>(out, in);
+      default:
+         throw Invalid_Argument("Unsupported size for poly_double_n_le");
+      }
+   }
+
+}