diff options
| -rw-r--r-- | src/lib/pubkey/eckcdsa/eckcdsa.cpp | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/src/lib/pubkey/eckcdsa/eckcdsa.cpp b/src/lib/pubkey/eckcdsa/eckcdsa.cpp index 9427e90ff..a7910e898 100644 --- a/src/lib/pubkey/eckcdsa/eckcdsa.cpp +++ b/src/lib/pubkey/eckcdsa/eckcdsa.cpp @@ -102,7 +102,7 @@ ECKCDSA_Signature_Operation::raw_sign(const byte msg[], size_t, BOTAN_ASSERT(s != 0, "invalid s"); secure_vector<byte> output = BigInt::encode_1363(r, c.size()); - output += BigInt::encode_1363(s, m_mod_order.get_modulus().bytes()); + output += BigInt::encode_1363(s, m_order.bytes()); return output; } @@ -155,20 +155,18 @@ class ECKCDSA_Verification_Operation : public PK_Ops::Verification_with_EMSA bool ECKCDSA_Verification_Operation::verify(const byte msg[], size_t, const byte sig[], size_t sig_len) { - // check that bit length of r is equal to output bit length of employed hash function h const std::unique_ptr<HashFunction> hash = HashFunction::create(hash_for_signature()); - - // no way to know size of r in sig, so check that we have at least hash->output_length()+1 - // bytes in sig, enough for r and an arbitrary size s - if(sig_len <= hash->output_length()) + //calculate size of r + size_t size_r = std::min(hash -> output_length(), m_order.bytes()); + if(sig_len < size_r+m_order.bytes()) { return false; } - secure_vector<byte> r(sig, sig + hash->output_length()); + secure_vector<byte> r(sig, sig + size_r); // check that 0 < s < q - const BigInt s(sig + hash->output_length(), sig_len - hash->output_length()); + const BigInt s(sig + size_r, m_order.bytes()); if(s <= 0 || s >= m_order) { @@ -179,8 +177,8 @@ bool ECKCDSA_Verification_Operation::verify(const byte msg[], size_t, xor_buf(r_xor_e, msg, r.size()); BigInt w(r_xor_e.data(), r_xor_e.size()); w = m_mod_order.reduce(w); - - const PointGFp q = (m_base_point * w) + (m_public_point * s); + + const PointGFp q = multi_exponentiate(m_base_point, w, m_public_point, s); const BigInt q_x = q.get_affine_x(); secure_vector<byte> c(q_x.bytes()); q_x.binary_encode(c.data()); |