Fix ECP leakage in Add() and Double() (GH #869, PR #871)

This check-in provides the fix for leaks in ECP's Add() and Double(). The fixes were taken from Joost Renes, Craig Costello, and Lejla Batina's [Complete addition formulas for prime order elliptic curves](https://eprint.iacr.org/2015/1060.pdf).

The Pull Request includes two additional changes that were related to testing the primary fix. First, an `AuthenticatedKeyAgreementWithRolesValidate` interface was added. It allows us to test key agreement when roles are involved. Roles are "client", "server", "initiator", "recipient", etc.

Second, `SetGlobalSeed` was added to `test.cpp` to help with reproducible results. We had code in two different places that set the seed value for the random number generator. But it was sloppy and doing a poor job since results could not be reproduced under some circumstances.

1 files changed, 10 insertions, 0 deletions

diff --git a/eccrypto.cpp b/eccrypto.cpp
index f76c495a..9a0914c0 100644
--- a/eccrypto.cpp
+++ b/eccrypto.cpp
@@ -28,6 +28,9 @@
 #include "ec2n.h"

 #include "misc.h"

 

+#include <iostream>

+#include <sstream>

+

 // Squash MS LNK4221 and libtool warnings

 #ifndef CRYPTOPP_MANUALLY_INSTANTIATE_TEMPLATES

 extern const char ECCRYPTO_FNAME[] = __FILE__;

@@ -683,6 +686,13 @@ OID DL_GroupParameters_EC<EC>::GetAlgorithmID() const
 	return ASN1::id_ecPublicKey();

 }

 

+std::ostream& operator<<(std::ostream& os, const DL_GroupParameters_EC<ECP>::Element& obj)

+{

+	std::ostringstream oss;

+	oss << "(" << std::hex << obj.x << ", " << std::hex  << obj.y << ")";

+	return os << oss.str();

+}

+

 // ******************************************************************

 

 template <class EC>