diff options
Diffstat (limited to 'src/lib/math/mp/mp_monty.cpp')
| -rw-r--r-- | src/lib/math/mp/mp_monty.cpp | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/src/lib/math/mp/mp_monty.cpp b/src/lib/math/mp/mp_monty.cpp index 820f41e6c..7e427b540 100644 --- a/src/lib/math/mp/mp_monty.cpp +++ b/src/lib/math/mp/mp_monty.cpp @@ -9,6 +9,7 @@ #include <botan/internal/mp_core.h> #include <botan/internal/mp_madd.h> #include <botan/internal/mp_asmi.h> +#include <botan/internal/ct_utils.h> #include <botan/mem_ops.h> namespace Botan { @@ -22,6 +23,10 @@ void bigint_monty_redc(word z[], { const size_t z_size = 2*(p_size+1); + CT::poison(z, z_size); + CT::poison(p, p_size); + CT::poison(ws, 2*(p_size+1)); + const size_t blocks_of_8 = p_size - (p_size % 8); for(size_t i = 0; i != p_size; ++i) @@ -47,10 +52,10 @@ void bigint_monty_redc(word z[], carry = (z_sum < z_i[p_size]); z_i[p_size] = z_sum; - for(size_t j = p_size + 1; carry && j != z_size - i; ++j) + for(size_t j = p_size + 1; j < z_size - i; ++j) { - ++z_i[j]; - carry = !z_i[j]; + z_i[j] += carry; + carry = carry & !z_i[j]; } } @@ -73,12 +78,18 @@ void bigint_monty_redc(word z[], ws[p_size] = word_sub(z[p_size+p_size], 0, &borrow); - BOTAN_ASSERT(borrow == 0 || borrow == 1, "Expected borrow"); - copy_mem(ws + p_size + 1, z + p_size, p_size + 1); - copy_mem(z, ws + borrow*(p_size+1), p_size + 1); + CT::conditional_copy_mem(borrow, z, ws + (p_size + 1), ws, (p_size + 1)); clear_mem(z + p_size + 1, z_size - p_size - 1); + + CT::unpoison(z, z_size); + CT::unpoison(p, p_size); + CT::unpoison(ws, 2*(p_size+1)); + + // This check comes after we've used it but that's ok here + CT::unpoison(&borrow, 1); + BOTAN_ASSERT(borrow == 0 || borrow == 1, "Expected borrow"); } void bigint_monty_mul(word z[], size_t z_size, |