1 files changed, 97 insertions, 0 deletions
diff --git a/src/lib/pubkey/ecdsa/ecdsa.cpp b/src/lib/pubkey/ecdsa/ecdsa.cpp
new file mode 100644
index 000000000..6ff082649
--- /dev/null
+++ b/src/lib/pubkey/ecdsa/ecdsa.cpp
@@ -0,0 +1,97 @@
+/*
+* ECDSA implemenation
+* (C) 2007 Manuel Hartl, FlexSecure GmbH
+*     2007 Falko Strenzke, FlexSecure GmbH
+*     2008-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/ecdsa.h>
+#include <botan/keypair.h>
+
+namespace Botan {
+
+bool ECDSA_PrivateKey::check_key(RandomNumberGenerator& rng,
+                                 bool strong) const
+   {
+   if(!public_point().on_the_curve())
+      return false;
+
+   if(!strong)
+      return true;
+
+   return KeyPair::signature_consistency_check(rng, *this, "EMSA1(SHA-1)");
+   }
+
+ECDSA_Signature_Operation::ECDSA_Signature_Operation(const ECDSA_PrivateKey& ecdsa) :
+   base_point(ecdsa.domain().get_base_point()),
+   order(ecdsa.domain().get_order()),
+   x(ecdsa.private_value()),
+   mod_order(order)
+   {
+   }
+
+secure_vector<byte>
+ECDSA_Signature_Operation::sign(const byte msg[], size_t msg_len,
+                                RandomNumberGenerator& rng)
+   {
+   rng.add_entropy(msg, msg_len);
+
+   BigInt m(msg, msg_len);
+
+   BigInt r = 0, s = 0;
+
+   while(r == 0 || s == 0)
+      {
+      // This contortion is necessary for the tests
+      BigInt k;
+      k.randomize(rng, order.bits());
+
+      while(k >= order)
+         k.randomize(rng, order.bits() - 1);
+
+      PointGFp k_times_P = base_point * k;
+      r = mod_order.reduce(k_times_P.get_affine_x());
+      s = mod_order.multiply(inverse_mod(k, order), mul_add(x, r, m));
+      }
+
+   secure_vector<byte> output(2*order.bytes());
+   r.binary_encode(&output[output.size() / 2 - r.bytes()]);
+   s.binary_encode(&output[output.size() - s.bytes()]);
+   return output;
+   }
+
+ECDSA_Verification_Operation::ECDSA_Verification_Operation(const ECDSA_PublicKey& ecdsa) :
+   base_point(ecdsa.domain().get_base_point()),
+   public_point(ecdsa.public_point()),
+   order(ecdsa.domain().get_order())
+   {
+   }
+
+bool ECDSA_Verification_Operation::verify(const byte msg[], size_t msg_len,
+                                          const byte sig[], size_t sig_len)
+   {
+   if(sig_len != order.bytes()*2)
+      return false;
+
+   BigInt e(msg, msg_len);
+
+   BigInt r(sig, sig_len / 2);
+   BigInt s(sig + sig_len / 2, sig_len / 2);
+
+   if(r <= 0 || r >= order || s <= 0 || s >= order)
+      return false;
+
+   BigInt w = inverse_mod(s, order);
+
+   PointGFp R = w * multi_exponentiate(base_point, e,
+                                       public_point, r);
+
+   if(R.is_zero())
+      return false;
+
+   return (R.get_affine_x() % order == r);
+   }
+
+}