1 files changed, 104 insertions, 0 deletions
diff --git a/src/core/nr_op.cpp b/src/core/nr_op.cpp
new file mode 100644
index 000000000..01e96a822
--- /dev/null
+++ b/src/core/nr_op.cpp
@@ -0,0 +1,104 @@
+/*************************************************
+* NR Operations Source File                      *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/eng_def.h>
+#include <botan/pow_mod.h>
+#include <botan/numthry.h>
+#include <botan/reducer.h>
+
+namespace Botan {
+
+namespace {
+
+/*************************************************
+* Default NR Operation                           *
+*************************************************/
+class Default_NR_Op : public NR_Operation
+   {
+   public:
+      SecureVector<byte> verify(const byte[], u32bit) const;
+      SecureVector<byte> sign(const byte[], u32bit, const BigInt&) const;
+
+      NR_Operation* clone() const { return new Default_NR_Op(*this); }
+
+      Default_NR_Op(const DL_Group&, const BigInt&, const BigInt&);
+   private:
+      const BigInt x, y;
+      const DL_Group group;
+      Fixed_Base_Power_Mod powermod_g_p, powermod_y_p;
+      Modular_Reducer mod_p, mod_q;
+   };
+
+/*************************************************
+* Default_NR_Op Constructor                      *
+*************************************************/
+Default_NR_Op::Default_NR_Op(const DL_Group& grp, const BigInt& y1,
+                             const BigInt& x1) : x(x1), y(y1), group(grp)
+   {
+   powermod_g_p = Fixed_Base_Power_Mod(group.get_g(), group.get_p());
+   powermod_y_p = Fixed_Base_Power_Mod(y, group.get_p());
+   mod_p = Modular_Reducer(group.get_p());
+   mod_q = Modular_Reducer(group.get_q());
+   }
+
+/*************************************************
+* Default NR Verify Operation                    *
+*************************************************/
+SecureVector<byte> Default_NR_Op::verify(const byte in[], u32bit length) const
+   {
+   const BigInt& q = group.get_q();
+
+   if(length != 2*q.bytes())
+      return false;
+
+   BigInt c(in, q.bytes());
+   BigInt d(in + q.bytes(), q.bytes());
+
+   if(c.is_zero() || c >= q || d >= q)
+      throw Invalid_Argument("Default_NR_Op::verify: Invalid signature");
+
+   BigInt i = mod_p.multiply(powermod_g_p(d), powermod_y_p(c));
+   return BigInt::encode(mod_q.reduce(c - i));
+   }
+
+/*************************************************
+* Default NR Sign Operation                      *
+*************************************************/
+SecureVector<byte> Default_NR_Op::sign(const byte in[], u32bit length,
+                                       const BigInt& k) const
+   {
+   if(x == 0)
+      throw Internal_Error("Default_NR_Op::sign: No private key");
+
+   const BigInt& q = group.get_q();
+
+   BigInt f(in, length);
+
+   if(f >= q)
+      throw Invalid_Argument("Default_NR_Op::sign: Input is out of range");
+
+   BigInt c = mod_q.reduce(powermod_g_p(k) + f);
+   if(c.is_zero())
+      throw Internal_Error("Default_NR_Op::sign: c was zero");
+   BigInt d = mod_q.reduce(k - x * c);
+
+   SecureVector<byte> output(2*q.bytes());
+   c.binary_encode(output + (output.size() / 2 - c.bytes()));
+   d.binary_encode(output + (output.size() - d.bytes()));
+   return output;
+   }
+
+}
+
+/*************************************************
+* Acquire a NR op                                *
+*************************************************/
+NR_Operation* Default_Engine::nr_op(const DL_Group& group, const BigInt& y,
+                                    const BigInt& x) const
+   {
+   return new Default_NR_Op(group, y, x);
+   }
+
+}