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135 lines
3.8 KiB
135 lines
3.8 KiB
/*==LICENSE==* |
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CyanWorlds.com Engine - MMOG client, server and tools |
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Copyright (C) 2011 Cyan Worlds, Inc. |
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This program is free software: you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation, either version 3 of the License, or |
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(at your option) any later version. |
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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You should have received a copy of the GNU General Public License |
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along with this program. If not, see <http://www.gnu.org/licenses/>. |
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You can contact Cyan Worlds, Inc. by email legal@cyan.com |
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or by snail mail at: |
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Cyan Worlds, Inc. |
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14617 N Newport Hwy |
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Mead, WA 99021 |
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*==LICENSE==*/ |
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/***************************************************************************** |
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* |
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* $/Plasma20/Sources/Plasma/NucleusLib/pnNetCli/pnNcEncrypt.cpp |
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* |
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***/ |
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#include "Pch.h" |
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#pragma hdrstop |
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namespace pnNetCli { |
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/**************************************************************************** |
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* |
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* Diffie-Hellman constants |
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* |
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// g and n are pregenerated and published |
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// (built into both client and server software) |
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BigNum g(4); |
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BigNum n; n.RandPrime(kKeyBits, &seed); |
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// a and x are pregenerated; a is built into server software, and x is |
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// built into client software |
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BigNum a; a.Rand(kKeyBits, &seed); |
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BigNum x; x.PowMod(g, a, n); |
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// client chooses b and y on connect, and sends y to the server |
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BigNum b; b.Rand(kKeyBits, &seed); |
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BigNum y; y.PowMod(g, b, n); |
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// server computes key: k = y^a mod n |
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BigNum ka; ka.PowMod(y, a, n); |
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// client computes key: k = x^b mod n |
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BigNum kb; kb.PowMod(x, b, n); |
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***/ |
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COMPILER_ASSERT(IS_POW2(kNetDiffieHellmanKeyBits)); |
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/***************************************************************************** |
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* |
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* Private |
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* |
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***/ |
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//============================================================================ |
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// TODO: Cache computed keys |
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static void GetCachedServerKey ( |
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NetMsgChannel * channel, |
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BigNum * ka, |
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const BigNum & dh_y |
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) { |
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// Get diffie-hellman constants |
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unsigned DH_G; |
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const BigNum * DH_A; |
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const BigNum * DH_N; |
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NetMsgChannelGetDhConstants(channel, &DH_G, &DH_A, &DH_N); |
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// Compute the result |
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ka->PowMod(dh_y, *DH_A, *DH_N); |
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} |
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/***************************************************************************** |
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* |
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* Module functions |
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* |
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***/ |
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//============================================================================ |
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void NetMsgCryptClientStart ( |
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NetMsgChannel * channel, |
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unsigned seedBytes, |
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const byte seedData[], |
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BigNum * clientSeed, |
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BigNum * serverSeed |
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) { |
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unsigned DH_G; |
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const BigNum * DH_X; |
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const BigNum * DH_N; |
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NetMsgChannelGetDhConstants(channel, &DH_G, &DH_X, &DH_N); |
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// Client chooses b and y on connect |
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BigNum g(DH_G); |
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BigNum seed(seedBytes, seedData); |
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BigNum b; b.Rand(kNetDiffieHellmanKeyBits, &seed); |
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// Client computes key: kb = x^b mod n |
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clientSeed->PowMod(*DH_X, b, *DH_N); |
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// Client sends y to server |
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serverSeed->PowMod(g, b, *DH_N); |
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} |
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//============================================================================ |
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void NetMsgCryptServerConnect ( |
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NetMsgChannel * channel, |
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unsigned seedBytes, |
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const byte seedData[], |
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BigNum * clientSeed |
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) { |
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// Server computes client key: ka = y^a mod n |
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const BigNum dh_y(seedBytes, seedData); |
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GetCachedServerKey(channel, clientSeed, dh_y); |
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} |
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} // namespace pnNetCli
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