1 files changed, 143 insertions, 0 deletions
diff --git a/src/lib/pubkey/dsa/dsa.cpp b/src/lib/pubkey/dsa/dsa.cpp
new file mode 100644
index 000000000..5d56d6b89
--- /dev/null
+++ b/src/lib/pubkey/dsa/dsa.cpp
@@ -0,0 +1,143 @@
+/*
+* DSA
+* (C) 1999-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/dsa.h>
+#include <botan/numthry.h>
+#include <botan/keypair.h>
+#include <future>
+namespace Botan {
+
+/*
+* DSA_PublicKey Constructor
+*/
+DSA_PublicKey::DSA_PublicKey(const DL_Group& grp, const BigInt& y1)
+   {
+   group = grp;
+   y = y1;
+   }
+
+/*
+* Create a DSA private key
+*/
+DSA_PrivateKey::DSA_PrivateKey(RandomNumberGenerator& rng,
+                               const DL_Group& grp,
+                               const BigInt& x_arg)
+   {
+   group = grp;
+   x = x_arg;
+
+   if(x == 0)
+      x = BigInt::random_integer(rng, 2, group_q() - 1);
+
+   y = power_mod(group_g(), x, group_p());
+
+   if(x_arg == 0)
+      gen_check(rng);
+   else
+      load_check(rng);
+   }
+
+DSA_PrivateKey::DSA_PrivateKey(const AlgorithmIdentifier& alg_id,
+                               const secure_vector<byte>& key_bits,
+                               RandomNumberGenerator& rng) :
+   DL_Scheme_PrivateKey(alg_id, key_bits, DL_Group::ANSI_X9_57)
+   {
+   y = power_mod(group_g(), x, group_p());
+
+   load_check(rng);
+   }
+
+/*
+* Check Private DSA Parameters
+*/
+bool DSA_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const
+   {
+   if(!DL_Scheme_PrivateKey::check_key(rng, strong) || x >= group_q())
+      return false;
+
+   if(!strong)
+      return true;
+
+   return KeyPair::signature_consistency_check(rng, *this, "EMSA1(SHA-1)");
+   }
+
+DSA_Signature_Operation::DSA_Signature_Operation(const DSA_PrivateKey& dsa) :
+   q(dsa.group_q()),
+   x(dsa.get_x()),
+   powermod_g_p(dsa.group_g(), dsa.group_p()),
+   mod_q(dsa.group_q())
+   {
+   }
+
+secure_vector<byte>
+DSA_Signature_Operation::sign(const byte msg[], size_t msg_len,
+                              RandomNumberGenerator& rng)
+   {
+   rng.add_entropy(msg, msg_len);
+
+   BigInt i(msg, msg_len);
+   BigInt r = 0, s = 0;
+
+   while(r == 0 || s == 0)
+      {
+      BigInt k;
+      do
+         k.randomize(rng, q.bits());
+      while(k >= q);
+
+      auto future_r = std::async(std::launch::async,
+                            [&]() { return mod_q.reduce(powermod_g_p(k)); });
+
+      s = inverse_mod(k, q);
+      r = future_r.get();
+      s = mod_q.multiply(s, mul_add(x, r, i));
+      }
+
+   secure_vector<byte> output(2*q.bytes());
+   r.binary_encode(&output[output.size() / 2 - r.bytes()]);
+   s.binary_encode(&output[output.size() - s.bytes()]);
+   return output;
+   }
+
+DSA_Verification_Operation::DSA_Verification_Operation(const DSA_PublicKey& dsa) :
+   q(dsa.group_q()), y(dsa.get_y())
+   {
+   powermod_g_p = Fixed_Base_Power_Mod(dsa.group_g(), dsa.group_p());
+   powermod_y_p = Fixed_Base_Power_Mod(y, dsa.group_p());
+   mod_p = Modular_Reducer(dsa.group_p());
+   mod_q = Modular_Reducer(dsa.group_q());
+   }
+
+bool DSA_Verification_Operation::verify(const byte msg[], size_t msg_len,
+                                        const byte sig[], size_t sig_len)
+   {
+   const BigInt& q = mod_q.get_modulus();
+
+   if(sig_len != 2*q.bytes() || msg_len > q.bytes())
+      return false;
+
+   BigInt r(sig, q.bytes());
+   BigInt s(sig + q.bytes(), q.bytes());
+   BigInt i(msg, msg_len);
+
+   if(r <= 0 || r >= q || s <= 0 || s >= q)
+      return false;
+
+   s = inverse_mod(s, q);
+
+   auto future_s_i = std::async(std::launch::async,
+      [&]() { return powermod_g_p(mod_q.multiply(s, i)); });
+
+   BigInt s_r = powermod_y_p(mod_q.multiply(s, r));
+   BigInt s_i = future_s_i.get();
+
+   s = mod_p.multiply(s_i, s_r);
+
+   return (mod_q.reduce(s) == r);
+   }
+
+}