1 files changed, 124 insertions, 0 deletions
diff --git a/botan/src/engine/gnump/gmp_dsa.cpp b/botan/src/engine/gnump/gmp_dsa.cpp
new file mode 100644
index 0000000..69a9c3e
--- /dev/null
+++ b/botan/src/engine/gnump/gmp_dsa.cpp
@@ -0,0 +1,124 @@
+/*
+* GMP DSA Engine
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/eng_gmp.h>
+#include <botan/gmp_wrap.h>
+#include <gmp.h>
+
+namespace Botan {
+
+#if defined(BOTAN_HAS_DSA)
+
+namespace {
+
+/*
+* GMP DSA Operation
+*/
+class GMP_DSA_Op : public DSA_Operation
+   {
+   public:
+      bool verify(const byte[], u32bit, const byte[], u32bit) const;
+      SecureVector<byte> sign(const byte[], u32bit, const BigInt&) const;
+
+      DSA_Operation* clone() const { return new GMP_DSA_Op(*this); }
+
+      GMP_DSA_Op(const DL_Group& group, const BigInt& y1, const BigInt& x1) :
+         x(x1), y(y1), p(group.get_p()), q(group.get_q()), g(group.get_g()) {}
+   private:
+      const GMP_MPZ x, y, p, q, g;
+   };
+
+/*
+* GMP DSA Verify Operation
+*/
+bool GMP_DSA_Op::verify(const byte msg[], u32bit msg_len,
+                        const byte sig[], u32bit sig_len) const
+   {
+   const u32bit q_bytes = q.bytes();
+
+   if(sig_len != 2*q_bytes || msg_len > q_bytes)
+      return false;
+
+   GMP_MPZ r(sig, q_bytes);
+   GMP_MPZ s(sig + q_bytes, q_bytes);
+   GMP_MPZ i(msg, msg_len);
+
+   if(mpz_cmp_ui(r.value, 0) <= 0 || mpz_cmp(r.value, q.value) >= 0)
+      return false;
+   if(mpz_cmp_ui(s.value, 0) <= 0 || mpz_cmp(s.value, q.value) >= 0)
+      return false;
+
+   if(mpz_invert(s.value, s.value, q.value) == 0)
+      return false;
+
+   GMP_MPZ si;
+   mpz_mul(si.value, s.value, i.value);
+   mpz_mod(si.value, si.value, q.value);
+   mpz_powm(si.value, g.value, si.value, p.value);
+
+   GMP_MPZ sr;
+   mpz_mul(sr.value, s.value, r.value);
+   mpz_mod(sr.value, sr.value, q.value);
+   mpz_powm(sr.value, y.value, sr.value, p.value);
+
+   mpz_mul(si.value, si.value, sr.value);
+   mpz_mod(si.value, si.value, p.value);
+   mpz_mod(si.value, si.value, q.value);
+
+   if(mpz_cmp(si.value, r.value) == 0)
+      return true;
+   return false;
+   }
+
+/*
+* GMP DSA Sign Operation
+*/
+SecureVector<byte> GMP_DSA_Op::sign(const byte in[], u32bit length,
+                                    const BigInt& k_bn) const
+   {
+   if(mpz_cmp_ui(x.value, 0) == 0)
+      throw Internal_Error("GMP_DSA_Op::sign: No private key");
+
+   GMP_MPZ i(in, length);
+   GMP_MPZ k(k_bn);
+
+   GMP_MPZ r;
+   mpz_powm(r.value, g.value, k.value, p.value);
+   mpz_mod(r.value, r.value, q.value);
+
+   mpz_invert(k.value, k.value, q.value);
+
+   GMP_MPZ s;
+   mpz_mul(s.value, x.value, r.value);
+   mpz_add(s.value, s.value, i.value);
+   mpz_mul(s.value, s.value, k.value);
+   mpz_mod(s.value, s.value, q.value);
+
+   if(mpz_cmp_ui(r.value, 0) == 0 || mpz_cmp_ui(s.value, 0) == 0)
+      throw Internal_Error("GMP_DSA_Op::sign: r or s was zero");
+
+   const u32bit q_bytes = q.bytes();
+
+   SecureVector<byte> output(2*q_bytes);
+   r.encode(output, q_bytes);
+   s.encode(output + q_bytes, q_bytes);
+   return output;
+   }
+
+}
+
+/*
+* Acquire a DSA op
+*/
+DSA_Operation* GMP_Engine::dsa_op(const DL_Group& group, const BigInt& y,
+                                  const BigInt& x) const
+   {
+   return new GMP_DSA_Op(group, y, x);
+   }
+#endif
+
+}