diff options
| -rw-r--r-- | src/lib/pubkey/ec_group/ec_group.cpp | 11 | ||||
| -rw-r--r-- | src/lib/pubkey/ec_group/ec_group.h | 5 | ||||
| -rw-r--r-- | src/tests/unit_ecc.cpp | 7 |
3 files changed, 22 insertions, 1 deletions
diff --git a/src/lib/pubkey/ec_group/ec_group.cpp b/src/lib/pubkey/ec_group/ec_group.cpp index a41a59b66..26af32a16 100644 --- a/src/lib/pubkey/ec_group/ec_group.cpp +++ b/src/lib/pubkey/ec_group/ec_group.cpp @@ -43,7 +43,8 @@ class EC_Group_Data final m_base_mult(m_base_point, 5), m_oid(oid), m_p_bits(p.bits()), - m_order_bits(order.bits()) + m_order_bits(order.bits()), + m_a_is_minus_3(a == p - 3) { #if defined(BOTAN_HAS_SYSTEM_RNG) m_base_mult.randomize(system_rng()); @@ -77,6 +78,8 @@ class EC_Group_Data final const CurveGFp& curve() const { return m_curve; } const PointGFp& base_point() const { return m_base_point; } + bool a_is_minus_3() const { return m_a_is_minus_3; } + BigInt mod_order(const BigInt& x) const { return m_mod_order.reduce(x); } BigInt multiply_mod_order(const BigInt& x, const BigInt& y) const @@ -101,6 +104,7 @@ class EC_Group_Data final OID m_oid; size_t m_p_bits; size_t m_order_bits; + bool m_a_is_minus_3; }; class EC_Group_Data_Map final @@ -365,6 +369,11 @@ const CurveGFp& EC_Group::get_curve() const return data().curve(); } +bool EC_Group::a_is_minus_3() const + { + return data().a_is_minus_3(); + } + size_t EC_Group::get_p_bits() const { return data().p_bits(); diff --git a/src/lib/pubkey/ec_group/ec_group.h b/src/lib/pubkey/ec_group/ec_group.h index 0e5f352f2..16a6abe28 100644 --- a/src/lib/pubkey/ec_group/ec_group.h +++ b/src/lib/pubkey/ec_group/ec_group.h @@ -126,6 +126,11 @@ class BOTAN_PUBLIC_API(2,0) EC_Group final BOTAN_DEPRECATED("Avoid CurveGFp") const CurveGFp& get_curve() const; /** + * Return if a == -3 mod p + */ + bool a_is_minus_3() const; + + /** * Return the size of p in bits (same as get_p().bits()) */ size_t get_p_bits() const; diff --git a/src/tests/unit_ecc.cpp b/src/tests/unit_ecc.cpp index 1a2f1d61c..166dfcd14 100644 --- a/src/tests/unit_ecc.cpp +++ b/src/tests/unit_ecc.cpp @@ -281,6 +281,13 @@ Test::Result test_groups() result.confirm("EC_Group is known", !group.get_curve_oid().empty()); result.test_eq("EC_Group has correct bit size", group.get_p().bits(), group.get_p_bits()); result.test_eq("EC_Group has byte size", group.get_p().bytes(), group.get_p_bytes()); + + bool a_is_minus_3 = group.a_is_minus_3(); + + if(a_is_minus_3) + result.test_eq("Group A equals -3", group.get_a(), group.get_p() - 3); + else + result.test_ne("Group " + group_name + " A does not equal -3", group.get_a(), group.get_p() - 3); } return result; } |