3 files changed, 7 insertions, 0 deletions
diff --git a/src/lib/math/mp/mp_misc.cpp b/src/lib/math/mp/mp_misc.cpp
index 4f24765bb..3b8be177e 100644
--- a/src/lib/math/mp/mp_misc.cpp
+++ b/src/lib/math/mp/mp_misc.cpp
@@ -43,6 +43,9 @@ s32bit bigint_cmp(const word x[], size_t x_size,
 */
 word bigint_divop(word n1, word n0, word d)
    {
+   if(d == 0)
+      throw std::runtime_error("bigint_divop divide by zero");
+
    word high = n1 % d, quotient = 0;
 
    for(size_t i = 0; i != MP_WORD_BITS; ++i)
diff --git a/src/lib/math/numbertheory/numthry.cpp b/src/lib/math/numbertheory/numthry.cpp
index fe943cc6b..900e61724 100644
--- a/src/lib/math/numbertheory/numthry.cpp
+++ b/src/lib/math/numbertheory/numthry.cpp
@@ -176,6 +176,9 @@ BigInt inverse_mod(const BigInt& n, const BigInt& mod)
 
 word monty_inverse(word input)
    {
+   if(input == 0)
+      throw std::runtime_error("monty_inverse: divide by zero");
+
    word b = input;
    word x2 = 1, x1 = 0, y2 = 0, y1 = 1;
 
diff --git a/src/lib/math/numbertheory/powm_mnt.cpp b/src/lib/math/numbertheory/powm_mnt.cpp
index c8bf0928c..5e797b195 100644
--- a/src/lib/math/numbertheory/powm_mnt.cpp
+++ b/src/lib/math/numbertheory/powm_mnt.cpp
@@ -137,6 +137,7 @@ Montgomery_Exponentiator::Montgomery_Exponentiator(const BigInt& mod,
    const BigInt r = BigInt::power_of_2(m_mod_words * BOTAN_MP_WORD_BITS);
    m_R_mod = r % m_modulus;
    m_R2_mod = (m_R_mod * m_R_mod) % m_modulus;
+   m_exp_bits = 0;
    }
 
 }