Support 1024-bit inputs in poly_double function

GH #1477

2 files changed, 36 insertions, 14 deletions

diff --git a/src/lib/utils/poly_dbl/poly_dbl.cpp b/src/lib/utils/poly_dbl/poly_dbl.cpp
index 2b989db57..62c7695da 100644
--- a/src/lib/utils/poly_dbl/poly_dbl.cpp
+++ b/src/lib/utils/poly_dbl/poly_dbl.cpp
@@ -1,5 +1,5 @@
 /*
-* (C) 2017 Jack Lloyd
+* (C) 2017,2018 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -12,12 +12,28 @@ namespace Botan {
 
 namespace {
 
-template<size_t LIMBS, uint64_t POLY>
+/*
+* The minimum weight irreducible binary polynomial of size n
+*
+* See http://www.hpl.hp.com/techreports/98/HPL-98-135.pdf
+*/
+enum class MinWeightPolynomial : uint64_t {
+   P64   = 0x1B,
+   P128  = 0x87,
+   P192  = 0x87,
+   P256  = 0x425,
+   P512  = 0x125,
+   P1024 = 0x80043,
+};
+
+template<size_t LIMBS, MinWeightPolynomial P>
 void poly_double(uint8_t out[], const uint8_t in[])
    {
    uint64_t W[LIMBS];
    load_be(W, in, LIMBS);
 
+   const uint64_t POLY = static_cast<uint64_t>(P);
+
    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);
@@ -26,12 +42,14 @@ void poly_double(uint8_t out[], const uint8_t in[])
    copy_out_be(out, LIMBS*8, W);
    }
 
-template<size_t LIMBS, uint64_t POLY>
+template<size_t LIMBS, MinWeightPolynomial P>
 void poly_double_le(uint8_t out[], const uint8_t in[])
    {
    uint64_t W[LIMBS];
    load_le(W, in, LIMBS);
 
+   const uint64_t POLY = static_cast<uint64_t>(P);
+
    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);
@@ -47,15 +65,17 @@ 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);
+         return poly_double<1, MinWeightPolynomial::P64>(out, in);
       case 16:
-         return poly_double<2, 0x87>(out, in);
+         return poly_double<2, MinWeightPolynomial::P128>(out, in);
       case 24:
-         return poly_double<3, 0x87>(out, in);
+         return poly_double<3, MinWeightPolynomial::P192>(out, in);
       case 32:
-         return poly_double<4, 0x425>(out, in);
+         return poly_double<4, MinWeightPolynomial::P256>(out, in);
       case 64:
-         return poly_double<8, 0x125>(out, in);
+         return poly_double<8, MinWeightPolynomial::P512>(out, in);
+      case 128:
+         return poly_double<8, MinWeightPolynomial::P1024>(out, in);
       default:
          throw Invalid_Argument("Unsupported size for poly_double_n");
       }
@@ -66,15 +86,17 @@ 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);
+         return poly_double_le<1, MinWeightPolynomial::P64>(out, in);
       case 16:
-         return poly_double_le<2, 0x87>(out, in);
+         return poly_double_le<2, MinWeightPolynomial::P128>(out, in);
       case 24:
-         return poly_double_le<3, 0x87>(out, in);
+         return poly_double_le<3, MinWeightPolynomial::P192>(out, in);
       case 32:
-         return poly_double_le<4, 0x425>(out, in);
+         return poly_double_le<4, MinWeightPolynomial::P256>(out, in);
       case 64:
-         return poly_double_le<8, 0x125>(out, in);
+         return poly_double_le<8, MinWeightPolynomial::P512>(out, in);
+      case 128:
+         return poly_double_le<8, MinWeightPolynomial::P1024>(out, in);
       default:
          throw Invalid_Argument("Unsupported size for poly_double_n_le");
       }
diff --git a/src/lib/utils/poly_dbl/poly_dbl.h b/src/lib/utils/poly_dbl/poly_dbl.h
index 8f9c0d3aa..931b4873e 100644
--- a/src/lib/utils/poly_dbl/poly_dbl.h
+++ b/src/lib/utils/poly_dbl/poly_dbl.h
@@ -21,7 +21,7 @@ void BOTAN_PUBLIC_API(2,3) poly_double_n(uint8_t out[], const uint8_t in[], size
 */
 inline bool poly_double_supported_size(size_t n)
    {
-   return (n == 8 || n == 16 || n == 24 || n == 32 || n == 64);
+   return (n == 8 || n == 16 || n == 24 || n == 32 || n == 64 || n == 128);
    }
 
 inline void poly_double_n(uint8_t buf[], size_t n)