Source code of Windows XP (NT5)
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/*-----------------------------------------------------------------------------
* Copyright (C) Microsoft Corporation, 1995 - 1996.
* All rights reserved.
*
* This file is part of the Microsoft Private Communication Technology
* reference implementation, version 1.0
*
* The Private Communication Technology reference implementation, version 1.0
* ("PCTRef"), is being provided by Microsoft to encourage the development and
* enhancement of an open standard for secure general-purpose business and
* personal communications on open networks. Microsoft is distributing PCTRef
* at no charge irrespective of whether you use PCTRef for non-commercial or
* commercial use.
*
* Microsoft expressly disclaims any warranty for PCTRef and all derivatives of
* it. PCTRef and any related documentation is provided "as is" without
* warranty of any kind, either express or implied, including, without
* limitation, the implied warranties or merchantability, fitness for a
* particular purpose, or noninfringement. Microsoft shall have no obligation
* to provide maintenance, support, upgrades or new releases to you or to anyone
* receiving from you PCTRef or your modifications. The entire risk arising out
* of use or performance of PCTRef remains with you.
*
* Please see the file LICENSE.txt,
* or http://pct.microsoft.com/pct/pctlicen.txt
* for more information on licensing.
*
* Please see http://pct.microsoft.com/pct/pct.htm for The Private
* Communication Technology Specification version 1.0 ("PCT Specification")
*
* 1/23/96
*----------------------------------------------------------------------------*/
//
// This file exports four functions: InitializeRNG, ShutdownRNG, GenRandom, and
// GenerateRandomBits, which are used to generate random sequences of bytes.
//
#include <windows.h>
#include <rng.h>
#include <rc4.h>
#include <sha.h>
#define A_SHA_DIGEST_LEN 20
#define RAND_CTXT_LEN 60
#define RC4_REKEY_PARAM 500 // rekey every 500 bytes
#define UNLEN MAX_PATH
typedef struct _RandContext
{
DWORD dwBitsFilled;
BYTE rgbBitBuffer[RAND_CTXT_LEN];
} RandContext;
#if 0
CRITICAL_SECTION csRNG;
#define LockRNG() EnterCriticalSection( &csRNG )
#define UnlockRNG() LeaveCriticalSection( &csRNG )
#else
#define LockRNG()
#define UnlockRNG()
#endif
unsigned char g_rgbStaticBits[A_SHA_DIGEST_LEN];
static DWORD g_dwRC4BytesUsed = RC4_REKEY_PARAM; // initially force rekey
static struct RC4_KEYSTRUCT g_rc4key;
static BOOL RandomFillBuffer(BYTE *pbBuffer, DWORD *pdwLength);
static void GatherRandomBits(RandContext *prandContext);
static void AppendRand(RandContext* prandContext, void* pv, DWORD dwSize);
/*****************************************************************************/
VOID STInitializeRNG(VOID)
{
DWORD dwType;
DWORD dwSize;
LONG err;
#if 0
InitializeCriticalSection( &csRNG );
LockRNG();
// grab seed from persistent storage
// SPQueryPersistentSeed(g_rgbStaticBits, A_SHA_DIGEST_LEN);
#endif
g_dwRC4BytesUsed = RC4_REKEY_PARAM;
#if 0
UnlockRNG();
#endif
return;
}
VOID ShutdownRNG(VOID)
{
#if 0
DeleteCriticalSection( &csRNG );
#endif
// put seed into persistent storage
// SPSetPersistentSeed(g_rgbStaticBits, A_SHA_DIGEST_LEN);
return;
}
/*****************************************************************************/
int STGenRandom(PVOID Reserved,
UCHAR *pbBuffer,
size_t dwLength)
{
STGenerateRandomBits(pbBuffer, dwLength);
return TRUE;
}
/************************************************************************/
/* GenerateRandomBits generates a specified number of random bytes and */
/* places them into the specified buffer. */
/************************************************************************/
/* */
/* Pseudocode logic flow: */
/* */
/* if (bits streamed > threshold) */
/* { */
/* Gather_Bits() */
/* SHAMix_Bits(User, Gathered, Static -> Static) */
/* RC4Key(Static -> newRC4Key) */
/* SHABits(Static -> Static) // hash after RC4 key generation */
/* } */
/* else */
/* { */
/* SHAMix_Bits(User, Static -> Static) */
/* } */
/* */
/* RC4(newRC4Key -> outbuf) */
/* bits streamed += sizeof(outbuf) */
/* */
/************************************************************************/
VOID STGenerateRandomBits(PUCHAR pbBuffer,
ULONG dwLength)
{
DWORD dwBytesThisPass;
DWORD dwFilledBytes = 0;
// break request into chunks that we rekey between
LockRNG();
while(dwFilledBytes < dwLength)
{
dwBytesThisPass = dwLength - dwFilledBytes;
RandomFillBuffer(pbBuffer + dwFilledBytes, &dwBytesThisPass);
dwFilledBytes += dwBytesThisPass;
}
UnlockRNG();
}
/*****************************************************************************/
static BOOL RandomFillBuffer(BYTE *pbBuffer, DWORD *pdwLength)
{
// Variables from loading and storing the registry...
DWORD cbDataLen;
cbDataLen = A_SHA_DIGEST_LEN;
if(g_dwRC4BytesUsed >= RC4_REKEY_PARAM) {
// if we need to rekey
RandContext randContext;
randContext.dwBitsFilled = 0;
GatherRandomBits(&randContext);
// Mix all bits
{
A_SHA_CTX SHACtx;
A_SHAInit(&SHACtx);
// SHA the static bits
A_SHAUpdate(&SHACtx, g_rgbStaticBits, A_SHA_DIGEST_LEN);
// SHA the gathered bits
A_SHAUpdate(&SHACtx, randContext.rgbBitBuffer, randContext.dwBitsFilled);
// SHA the user-supplied bits
A_SHAUpdate(&SHACtx, pbBuffer, *pdwLength);
// output back out to static bits
A_SHAFinal(&SHACtx, g_rgbStaticBits);
}
// Create RC4 key
g_dwRC4BytesUsed = 0;
rc4_key(&g_rc4key, A_SHA_DIGEST_LEN, g_rgbStaticBits);
// Mix RC4 key bits around
{
A_SHA_CTX SHACtx;
A_SHAInit(&SHACtx);
// SHA the static bits
A_SHAUpdate(&SHACtx, g_rgbStaticBits, A_SHA_DIGEST_LEN);
// output back out to static bits
A_SHAFinal(&SHACtx, g_rgbStaticBits);
}
} else {
// Use current RC4 key, but capture any user-supplied bits.
// Mix input bits
{
A_SHA_CTX SHACtx;
A_SHAInit(&SHACtx);
// SHA the static bits
A_SHAUpdate(&SHACtx, g_rgbStaticBits, A_SHA_DIGEST_LEN);
// SHA the user-supplied bits
A_SHAUpdate(&SHACtx, pbBuffer, *pdwLength);
// output back out to static bits
A_SHAFinal(&SHACtx, g_rgbStaticBits);
}
}
// only use RC4_REKEY_PARAM bytes from each RC4 key
{
DWORD dwMaxPossibleBytes = RC4_REKEY_PARAM - g_dwRC4BytesUsed;
if(*pdwLength > dwMaxPossibleBytes) {
*pdwLength = dwMaxPossibleBytes;
}
}
FillMemory(pbBuffer, *pdwLength, 0);
rc4(&g_rc4key, *pdwLength, pbBuffer);
g_dwRC4BytesUsed += *pdwLength;
return TRUE;
}
/*****************************************************************************/
static void GatherRandomBits(RandContext *prandContext)
{
DWORD dwTmp;
WORD wTmp;
BYTE bTmp;
// ** indicates US DoD's specific recommendations for password generation
// proc id
dwTmp = GetCurrentProcessId();
AppendRand(prandContext, &dwTmp, sizeof(dwTmp));
// thread id
dwTmp = GetCurrentThreadId();
AppendRand(prandContext, &dwTmp, sizeof(dwTmp));
// ** ticks since boot (system clock)
dwTmp = GetTickCount();
AppendRand(prandContext, &dwTmp, sizeof(dwTmp));
// cursor position
{
POINT point;
GetCursorPos(&point);
bTmp = LOBYTE(point.x) ^ HIBYTE(point.x);
AppendRand(prandContext, &bTmp, sizeof(BYTE));
bTmp = LOBYTE(point.y) ^ HIBYTE(point.y);
AppendRand(prandContext, &bTmp, sizeof(BYTE));
}
// ** system time, in ms, sec, min (date & time)
{
SYSTEMTIME sysTime;
GetLocalTime(&sysTime);
AppendRand(prandContext, &sysTime.wMilliseconds, sizeof(sysTime.wMilliseconds));
bTmp = LOBYTE(sysTime.wSecond) ^ LOBYTE(sysTime.wMinute);
AppendRand(prandContext, &bTmp, sizeof(BYTE));
}
// ** hi-res performance counter (system counters)
{
LARGE_INTEGER liPerfCount;
if(QueryPerformanceCounter(&liPerfCount)) {
bTmp = LOBYTE(LOWORD(liPerfCount.LowPart)) ^ LOBYTE(LOWORD(liPerfCount.HighPart));
AppendRand(prandContext, &bTmp, sizeof(BYTE));
bTmp = HIBYTE(LOWORD(liPerfCount.LowPart)) ^ LOBYTE(LOWORD(liPerfCount.HighPart));
AppendRand(prandContext, &bTmp, sizeof(BYTE));
bTmp = LOBYTE(HIWORD(liPerfCount.LowPart)) ^ LOBYTE(LOWORD(liPerfCount.HighPart));
AppendRand(prandContext, &bTmp, sizeof(BYTE));
bTmp = HIBYTE(HIWORD(liPerfCount.LowPart)) ^ LOBYTE(LOWORD(liPerfCount.HighPart));
AppendRand(prandContext, &bTmp, sizeof(BYTE));
}
}
// memory status
{
MEMORYSTATUS mstMemStat;
mstMemStat.dwLength = sizeof(MEMORYSTATUS); // must-do
GlobalMemoryStatus(&mstMemStat);
wTmp = HIWORD(mstMemStat.dwAvailPhys); // low words seem to be always zero
AppendRand(prandContext, &wTmp, sizeof(WORD));
wTmp = HIWORD(mstMemStat.dwAvailPageFile);
AppendRand(prandContext, &wTmp, sizeof(WORD));
bTmp = LOBYTE(HIWORD(mstMemStat.dwAvailVirtual));
AppendRand(prandContext, &bTmp, sizeof(BYTE));
}
// free disk clusters
{
DWORD dwSectorsPerCluster, dwBytesPerSector, dwNumberOfFreeClusters, dwTotalNumberOfClusters;
if(GetDiskFreeSpace(NULL, &dwSectorsPerCluster, &dwBytesPerSector, &dwNumberOfFreeClusters, &dwTotalNumberOfClusters)) {
AppendRand(prandContext, &dwNumberOfFreeClusters, sizeof(dwNumberOfFreeClusters));
AppendRand(prandContext, &dwTotalNumberOfClusters, sizeof(dwTotalNumberOfClusters));
AppendRand(prandContext, &dwBytesPerSector, sizeof(dwBytesPerSector));
}
}
// last messages' timestamp
{
LONG lTime;
lTime = GetMessageTime();
AppendRand(prandContext, &lTime, sizeof(lTime));
}
{
static DWORD dwComputerNameSize;
static DWORD dwUserNameSize;
static char lpComputerName [MAX_COMPUTERNAME_LENGTH + 1];
static char lpUserName [UNLEN + 1];
//
// note use of two temp DWORDs - that's to keep the static DWORDs
// thread safe
//
// **SystemID
if(dwComputerNameSize == 0) {
DWORD dwTempComputerNameSize = MAX_COMPUTERNAME_LENGTH + 1;
if(GetComputerNameA(lpComputerName, &dwTempComputerNameSize))
dwComputerNameSize = dwTempComputerNameSize;
}
if(dwComputerNameSize != 0) {
// dwComputerNameSize = len not including null termination
AppendRand(prandContext, lpComputerName, dwComputerNameSize);
}
// **UserID
if(dwUserNameSize == 0) {
DWORD dwTempUserNameSize = UNLEN + 1;
if(GetUserNameA(lpUserName, &dwTempUserNameSize)) {
// dwUserNameSize = len including null termination
dwUserNameSize = dwTempUserNameSize - 1;
}
}
if(dwUserNameSize != 0) {
AppendRand(prandContext, lpUserName, dwUserNameSize);
}
}
}
/*****************************************************************************/
static void AppendRand(RandContext* prandContext, void* pv, DWORD dwSize)
{
DWORD dwBitsLeft = (RAND_CTXT_LEN - prandContext->dwBitsFilled);
if(dwBitsLeft > 0) {
if(dwSize > dwBitsLeft) {
dwSize = dwBitsLeft;
}
CopyMemory(prandContext->rgbBitBuffer + prandContext->dwBitsFilled, pv, dwSize);
prandContext->dwBitsFilled += dwSize;
}
}