From 87b06bf6cef4d850e6acf1c5c2ddda6119b802b7 Mon Sep 17 00:00:00 2001
From: weidai <weidai@57ff6487-cd31-0410-9ec3-f628ee90f5f0>
Date: Mon, 24 Sep 2007 02:54:22 +0000
Subject: [PATCH] update CheckMOVCondition() according to
 http://eprint.iacr.org/2007/343

---
 trunk/c5/eccrypto.cpp | 10 +++++++---
 trunk/c5/validat2.cpp |  6 +++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/trunk/c5/eccrypto.cpp b/trunk/c5/eccrypto.cpp
index 91ec54f1..f0ff9eeb 100644
--- a/trunk/c5/eccrypto.cpp
+++ b/trunk/c5/eccrypto.cpp
@@ -46,12 +46,16 @@ static inline Integer ConvertToInteger(const Integer &x)
 
 static bool CheckMOVCondition(const Integer &q, const Integer &r)
 {
-	Integer t=1;
-	unsigned int n=q.BitCount(), m=r.BitCount();
+	// see "Updated standards for validating elliptic curves", http://eprint.iacr.org/2007/343
+	Integer t = 1;
+	unsigned int n = q.IsEven() ? 1 : q.BitCount(), m = r.BitCount();
 
 	for (unsigned int i=n; DiscreteLogWorkFactor(i)<m/2; i+=n)
 	{
-		t = (t*q)%r;
+		if (q.IsEven())
+			t = (t+t)%r;
+		else
+			t = (t*q)%r;
 		if (t == 1)
 			return false;
 	}
diff --git a/trunk/c5/validat2.cpp b/trunk/c5/validat2.cpp
index aba5d6c7..b9ed7167 100644
--- a/trunk/c5/validat2.cpp
+++ b/trunk/c5/validat2.cpp
@@ -658,10 +658,10 @@ bool ValidateEC2N()
 #if 0	// TODO: turn this back on when I make EC2N faster for pentanomial basis
 	cout << "Testing SEC 2 recommended curves..." << endl;
 	OID oid;
-	while (!(oid = ECParameters<EC2N>::GetNextRecommendedParametersOID(oid)).m_values.empty())
+	while (!(oid = DL_GroupParameters_EC<EC2N>::GetNextRecommendedParametersOID(oid)).m_values.empty())
 	{
-		ECParameters<EC2N> params(oid);
-		bool fail = !params.ValidateParameters(GlobalRNG());
+		DL_GroupParameters_EC<EC2N> params(oid);
+		bool fail = !params.Validate(GlobalRNG(), 2);
 		cout << (fail ? "FAILED" : "passed") << "    " << params.GetCurve().GetField().MaxElementBitLength() << " bits" << endl;
 		pass = pass && !fail;
 	}