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cleanup and docs

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This commit is contained in:
Adam Ierymenko 2019-09-05 15:09:20 -07:00
parent 171d661b84
commit 274b2682d6
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GPG key ID: C8877CF2D7A5D7F3
2 changed files with 59 additions and 60 deletions
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93
node/Utils.cpp
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@ -146,69 +146,62 @@ void Utils::getSecureRandom(void *buf,unsigned int bytes)
static uint64_t randomState[4];
static uint8_t randomBuf[16384];
static unsigned long randomPtr = sizeof(randomBuf);
#ifdef __WINDOWS__
static HCRYPTPROV cryptProvider = NULL;
#endif
Mutex::Lock _l(globalLock);
/* Just for posterity we Salsa20 encrypt the result of whatever system
* CSPRNG we use. There have been several bugs at the OS or OS distribution
* level in the past that resulted in systematically weak or predictable
* keys due to random seeding problems. This mitigates that by grabbing
* a bit of extra entropy and further randomizing the result,and comes
* at almost no cost and with no real downside if the random source is
* good. */
if (unlikely(!initialized)) {
#ifdef __WINDOWS__
if (!CryptAcquireContextA(&cryptProvider,NULL,NULL,PROV_RSA_FULL,CRYPT_VERIFYCONTEXT|CRYPT_SILENT)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to obtain WinCrypt context!\r\n");
exit(1);
}
if (!CryptGenRandom(cryptProvider,(DWORD)sizeof(randomState),(BYTE *)randomState)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() CryptGenRandom failed!\r\n");
exit(1);
}
if (!CryptGenRandom(cryptProvider,(DWORD)sizeof(randomBuf),(BYTE *)randomBuf)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() CryptGenRandom failed!\r\n");
exit(1);
}
#else
int devURandomFd = ::open("/dev/urandom",O_RDONLY);
if (devURandomFd < 0) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to open /dev/urandom\n");
exit(1);
}
if ((int)::read(devURandomFd,randomState,sizeof(randomState)) != (int)sizeof(randomState)) {
::close(devURandomFd);
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to read from /dev/urandom\n");
exit(1);
}
if ((int)::read(devURandomFd,randomBuf,sizeof(randomBuf)) != (int)sizeof(randomBuf)) {
::close(devURandomFd);
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to read from /dev/urandom\n");
exit(1);
}
close(devURandomFd);
#endif
initialized = true;
}
Mutex::Lock gl(globalLock);
for(unsigned int i=0;i<bytes;++i) {
if (randomPtr >= sizeof(randomBuf)) {
randomPtr = 0;
for(unsigned int k=0;k<4;++k) {
if (++randomState[k])
break;
if (unlikely(!initialized)) {
initialized = true;
#ifdef __WINDOWS__
HCRYPTPROV cryptProvider = NULL;
if (!CryptAcquireContextA(&cryptProvider,NULL,NULL,PROV_RSA_FULL,CRYPT_VERIFYCONTEXT|CRYPT_SILENT)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to obtain WinCrypt context!\r\n");
exit(1);
}
if (!CryptGenRandom(cryptProvider,(DWORD)sizeof(randomState),(BYTE *)randomState)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() CryptGenRandom failed!\r\n");
exit(1);
}
if (!CryptGenRandom(cryptProvider,(DWORD)sizeof(randomBuf),(BYTE *)randomBuf)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() CryptGenRandom failed!\r\n");
exit(1);
}
CryptReleaseContext(cryptProvider,0);
#else
int devURandomFd = ::open("/dev/urandom",O_RDONLY);
if (devURandomFd < 0) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to open /dev/urandom\n");
exit(1);
}
if ((int)::read(devURandomFd,randomState,sizeof(randomState)) != (int)sizeof(randomState)) {
::close(devURandomFd);
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to read from /dev/urandom\n");
exit(1);
}
if ((int)::read(devURandomFd,randomBuf,sizeof(randomBuf)) != (int)sizeof(randomBuf)) {
::close(devURandomFd);
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to read from /dev/urandom\n");
exit(1);
}
close(devURandomFd);
#endif
randomState[0] ^= (uint64_t)time(nullptr);
randomState[1] ^= (uint64_t)((uintptr_t)buf); // XOR in some other entropy just in case the system random source is wonky
}
uint8_t h[48];
for(unsigned int k=0;k<4;++k) {
if (++randomState[k] != 0)
break;
}
HMACSHA384((const uint8_t *)randomState,randomBuf,sizeof(randomBuf),h);
AES c(h);
c.ctr(h + 32,randomBuf,sizeof(randomBuf),randomBuf);
}
((uint8_t *)buf)[i] = randomBuf[randomPtr++];
}
}