diff options
Diffstat (limited to 'src/lib/math/bigint')
| -rw-r--r-- | src/lib/math/bigint/big_ops2.cpp | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/src/lib/math/bigint/big_ops2.cpp b/src/lib/math/bigint/big_ops2.cpp index 39f985566..bd107f33a 100644 --- a/src/lib/math/bigint/big_ops2.cpp +++ b/src/lib/math/bigint/big_ops2.cpp @@ -133,6 +133,9 @@ BigInt& BigInt::mod_sub(const BigInt& s, const BigInt& mod, secure_vector<word>& if(t_sw > mod_sw || s_sw > mod_sw) throw Invalid_Argument("BigInt::mod_sub args larger than modulus"); + BOTAN_DEBUG_ASSERT(*this < mod); + BOTAN_DEBUG_ASSERT(s < mod); + int32_t relative_size = bigint_cmp(data(), t_sw, s.data(), s_sw); if(relative_size >= 0) @@ -144,9 +147,11 @@ BigInt& BigInt::mod_sub(const BigInt& s, const BigInt& mod, secure_vector<word>& { // Otherwise we must sub s and then add p (or add (p - s) as here) - ws.resize(mod_sw + 1); + if(ws.size() < mod_sw) + ws.resize(mod_sw); - bigint_sub3(ws.data(), mod.data(), mod_sw, s.data(), s_sw); + word borrow = bigint_sub3(ws.data(), mod.data(), mod_sw, s.data(), s_sw); + BOTAN_ASSERT_NOMSG(borrow == 0); if(m_reg.size() < mod_sw) grow_to(mod_sw); |