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CWE-ou-minkata
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if the N value is zero, send an empty seed to the server and expect an empty seed back. Don't use encryption.

diafero 13 years ago
parent
d5885dd677
commit
837dae9b69
4 changed files with 105 additions and 79 deletions
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  1. 6
      Sources/Plasma/NucleusLib/pnNetCli/pnNcChannel.cpp
  2. 146
      Sources/Plasma/NucleusLib/pnNetCli/pnNcCli.cpp
  3. 28
      Sources/Plasma/NucleusLib/pnNetCli/pnNcEncrypt.cpp
  4. 4
      Sources/Plasma/NucleusLib/pnUtils/Private/pnUtBigNum.h

6
Sources/Plasma/NucleusLib/pnNetCli/pnNcChannel.cpp
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@ -341,9 +341,9 @@ void NetMsgChannelGetDhConstants (
const BigNum ** dh_xa,
const BigNum ** dh_n
) {
*dh_g = channel->m_dh_g;
*dh_xa = &channel->m_dh_xa;
*dh_n = &channel->m_dh_n;
if (dh_g) *dh_g = channel->m_dh_g;
if (dh_xa) *dh_xa = &channel->m_dh_xa;
if (dh_n) *dh_n = &channel->m_dh_n;
}

146
Sources/Plasma/NucleusLib/pnNetCli/pnNcCli.cpp
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@ -40,8 +40,6 @@ You can contact Cyan Worlds, Inc. by email legal@cyan.com
# define NCCLI_LOG NULL_STMT
#endif
//#define NO_ENCRYPTION
#ifndef PLASMA_EXTERNAL_RELEASE
struct NetLogMessage_Header
@ -120,8 +118,8 @@ struct NetCli : THashKeyVal<Uuid> {
ENetCliMode mode;
FNetCliEncrypt encryptFcn;
byte seed[kNetMaxSymmetricSeedBytes];
CryptKey * cryptIn;
CryptKey * cryptOut;
CryptKey * cryptIn; // nil if encrytpion is disabled
CryptKey * cryptOut; // nil if encrytpion is disabled
void * encryptParam;
// Message buffers
@ -174,9 +172,8 @@ static void PutBufferOnWire (NetCli * cli, void * data, unsigned bytes) {
}
#endif // PLASMA_EXTERNAL_RELEASE
if (cli->mode == kNetCliModeEncrypted) {
if (cli->mode == kNetCliModeEncrypted && cli->cryptOut) {
// Encrypt data...
#ifndef NO_ENCRYPTION
if (bytes <= 2048)
// byte count is small, use stack-based buffer
temp = ALLOCA(byte, bytes);
@ -187,7 +184,6 @@ static void PutBufferOnWire (NetCli * cli, void * data, unsigned bytes) {
MemCopy(temp, data, bytes);
CryptEncrypt(cli->cryptOut, bytes, temp);
data = temp;
#endif
}
if (cli->sock)
AsyncSocketSend(cli->sock, data, bytes);
@ -644,7 +640,7 @@ static void ClientConnect (NetCli * cli) {
if (cli->sock) {
unsigned bytes;
NetCli_Cli2Srv_Connect msg;
unsigned char * data = serverSeed.GetData_LE(&bytes);
unsigned char * data = serverSeed.GetData_LE(&bytes); // will be 0 if encryption is disabled, and thereby send an empty seed
ASSERTMSG(bytes <= sizeof(msg.dh_y_data), "4");
msg.message = kNetCliCli2SrvConnect;
msg.length = (byte) (sizeof(msg) - sizeof(msg.dh_y_data) + bytes);
@ -668,48 +664,55 @@ static bool ServerRecvConnect (
* (const NetCli_Cli2Srv_Connect *) &pkt;
if (pkt.length < sizeof(msg))
return false;
int seedLength = msg.length - sizeof(pkt);
// Send the server seed to the client (unencrypted)
if (cli->sock) {
NetCli_Srv2Cli_Encrypt reply;
reply.message = kNetCliSrv2CliEncrypt;
reply.length = sizeof(reply);
reply.length = seedLength == 0 ? 0 : sizeof(reply); // reply with empty seed if we got empty seed (this means: no encryption)
MemCopy(reply.serverSeed, cli->seed, sizeof(reply.serverSeed));
AsyncSocketSend(cli->sock, &reply, sizeof(reply));
AsyncSocketSend(cli->sock, &reply, reply.length);
}
// Compute client seed
byte clientSeed[kNetMaxSymmetricSeedBytes];
{
if (seedLength == 0) { // client wishes no encryption (that's okay, nobody else can "fake" us as nobody has the private key, so if the client actually wants encryption it will only work with the correct peer)
cli->cryptIn = nil;
cli->cryptOut = nil;
}
else {
// Compute client seed
byte clientSeed[kNetMaxSymmetricSeedBytes];
BigNum clientSeedValue;
NetMsgCryptServerConnect(
cli->channel,
msg.length - sizeof(pkt),
msg.dh_y_data,
&clientSeedValue
{
NetMsgCryptServerConnect(
cli->channel,
seedLength,
msg.dh_y_data,
&clientSeedValue
);
ZERO(clientSeed);
unsigned bytes;
unsigned char * data = clientSeedValue.GetData_LE(&bytes);
MemCopy(clientSeed, data, min(bytes, sizeof(clientSeed)));
delete [] data;
}
// Create the symmetric key from a combination
// of the client seed and the server seed
byte sharedSeed[kNetMaxSymmetricSeedBytes];
CreateSymmetricKey(
sizeof(cli->seed), cli->seed, // server seed
sizeof(clientSeed), clientSeed, // client seed
sizeof(sharedSeed), sharedSeed // combined seed
);
ZERO(clientSeed);
unsigned bytes;
unsigned char * data = clientSeedValue.GetData_LE(&bytes);
MemCopy(clientSeed, data, min(bytes, sizeof(clientSeed)));
delete [] data;
// Switch to encrypted mode
cli->cryptIn = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
cli->cryptOut = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
}
// Create the symmetric key from a combination
// of the client seed and the server seed
byte sharedSeed[kNetMaxSymmetricSeedBytes];
CreateSymmetricKey(
sizeof(cli->seed), cli->seed, // server seed
sizeof(clientSeed), clientSeed, // client seed
sizeof(sharedSeed), sharedSeed // combined seed
);
// Switch to encrypted mode
cli->mode = kNetCliModeEncrypted;
cli->cryptIn = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
cli->cryptOut = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
cli->mode = kNetCliModeEncrypted; // should rather be called "established", but whatever
return cli->encryptFcn(kNetSuccess, cli->encryptParam);
}
@ -722,26 +725,39 @@ static bool ClientRecvEncrypt (
if (cli->mode != kNetCliModeClientStart)
return false;
// Validate message size
// find out if we want encryption
const BigNum * DH_N;
NetMsgChannelGetDhConstants(cli->channel, nil, nil, &DH_N);
bool encrypt = !DH_N->isZero();
// Process message
const NetCli_Srv2Cli_Encrypt & msg =
* (const NetCli_Srv2Cli_Encrypt *) &pkt;
if (pkt.length != sizeof(msg))
return false;
if (encrypt) { // we insist on encryption, don't let some MitM decide for us!
if (pkt.length != sizeof(msg))
return false;
// Create the symmetric key from a combination
// of the client seed and the server seed
byte sharedSeed[kNetMaxSymmetricSeedBytes];
CreateSymmetricKey(
sizeof(msg.serverSeed), msg.serverSeed, // server seed
sizeof(cli->seed), cli->seed, // client seed
sizeof(sharedSeed), sharedSeed // combined seed
);
// Create the symmetric key from a combination
// of the client seed and the server seed
byte sharedSeed[kNetMaxSymmetricSeedBytes];
CreateSymmetricKey(
sizeof(msg.serverSeed), msg.serverSeed, // server seed
sizeof(cli->seed), cli->seed, // client seed
sizeof(sharedSeed), sharedSeed // combined seed
);
// Switch to encrypted mode
cli->mode = kNetCliModeEncrypted;
cli->cryptIn = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
cli->cryptOut = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
// Switch to encrypted mode
cli->cryptIn = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
cli->cryptOut = CryptKeyCreate(kCryptRc4, sizeof(sharedSeed), sharedSeed);
}
else { // honestly we do not care what the other side sends, we will send plaintext
if (pkt.length != sizeof(pkt))
return false;
cli->cryptIn = nil;
cli->cryptOut = nil;
}
cli->mode = kNetCliModeEncrypted; // should rather be called "established", but whatever
return cli->encryptFcn(kNetSuccess, cli->encryptParam);
}
@ -1061,18 +1077,18 @@ bool NetCliDispatch (
// Decrypt data...
byte * temp, * heap = NULL;
#ifndef NO_ENCRYPTION
if (bytes <= 2048)
// byte count is small, use stack-based buffer
temp = ALLOCA(byte, bytes);
else
// byte count is large, use heap-based buffer
temp = heap = (byte *)ALLOC(bytes);
MemCopy(temp, data, bytes);
CryptDecrypt(cli->cryptIn, bytes, temp);
data = temp;
#endif
if (cli->cryptIn) {
if (bytes <= 2048)
// byte count is small, use stack-based buffer
temp = ALLOCA(byte, bytes);
else
// byte count is large, use heap-based buffer
temp = heap = (byte *)ALLOC(bytes);
MemCopy(temp, data, bytes);
CryptDecrypt(cli->cryptIn, bytes, temp);
data = temp;
}
// Add data to accumulator and dispatch
cli->input.Add(bytes, data);

28
Sources/Plasma/NucleusLib/pnNetCli/pnNcEncrypt.cpp
Unescape View File

@ -83,6 +83,7 @@ static void GetCachedServerKey (
const BigNum * DH_A;
const BigNum * DH_N;
NetMsgChannelGetDhConstants(channel, &DH_G, &DH_A, &DH_N);
hsAssert(!DH_N->isZero(), "DH_N must not be zero in encrypted mode");
// Compute the result
ka->PowMod(dh_y, *DH_A, *DH_N);
@ -107,17 +108,22 @@ void NetMsgCryptClientStart (
const BigNum * DH_X;
const BigNum * DH_N;
NetMsgChannelGetDhConstants(channel, &DH_G, &DH_X, &DH_N);
// Client chooses b and y on connect
BigNum g(DH_G);
BigNum seed(seedBytes, seedData);
BigNum b; b.Rand(kNetDiffieHellmanKeyBits, &seed);
// Client computes key: kb = x^b mod n
clientSeed->PowMod(*DH_X, b, *DH_N);
// Client sends y to server
serverSeed->PowMod(g, b, *DH_N);
if (DH_N->isZero()) { // no actual encryption, but the caller expects a seed
clientSeed->SetZero();
serverSeed->SetZero();
}
else {
// Client chooses b and y on connect
BigNum g(DH_G);
BigNum seed(seedBytes, seedData);
BigNum b; b.Rand(kNetDiffieHellmanKeyBits, &seed);
// Client computes key: kb = x^b mod n
clientSeed->PowMod(*DH_X, b, *DH_N);
// Client sends y to server
serverSeed->PowMod(g, b, *DH_N);
}
}
//============================================================================

4
Sources/Plasma/NucleusLib/pnUtils/Private/pnUtBigNum.h
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@ -89,6 +89,10 @@ public:
{
return BN_cmp(&m_number, &a.m_number);
}
bool isZero() const
{
return BN_is_zero(&m_number);
}
void Div (const BigNum & a, dword b, dword * remainder)
{

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