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Merged PR 2886: CHERRY-PICK: MdePkg: TimerRngLib: Added RngLib that u…
…ses TimerLib This will get wiped out on the next integration (202012) https://windowspartners.visualstudio.com/MSCoreUEFI/_git/mu_basecore/commit/797c26dea17931447c848dc8db7fc15d499a19ea?refName=refs%2Fheads%2Frelease%2F202005
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Matthew Carlson
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Bret Barkelew
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Oct 15, 2020
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## @file | ||
# Instance of RNG (Random Number Generator) Library. | ||
# | ||
# BaseRng Library that uses the TimerLib to provide reasonably random numbers. | ||
# Do NOT use this on a production system as this uses the system performance | ||
# counter rather than a true source of random in addition to having a weak | ||
# random algorithm. This is provided primarily as a source of entropy for | ||
# OpenSSL for platforms that do not have a good built in RngLib as this | ||
# emulates what was done before (though it isn't perfect). | ||
# | ||
# Copyright (c) Microsoft Corporation. All rights reserved.<BR> | ||
# | ||
# SPDX-License-Identifier: BSD-2-Clause-Patent | ||
# | ||
# | ||
## | ||
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[Defines] | ||
INF_VERSION = 1.27 | ||
BASE_NAME = BaseRngLibTimerLib | ||
MODULE_UNI_FILE = BaseRngLibTimerLib.uni | ||
FILE_GUID = 74950C45-10FC-4AB5-B114-49C87C17409B | ||
MODULE_TYPE = BASE | ||
VERSION_STRING = 1.0 | ||
LIBRARY_CLASS = RngLib | ||
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[Sources] | ||
RngLibTimer.c | ||
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[Packages] | ||
MdePkg/MdePkg.dec | ||
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[LibraryClasses] | ||
BaseLib | ||
DebugLib | ||
TimerLib |
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// @file | ||
// Instance of RNG (Random Number Generator) Library. | ||
// | ||
// RngLib that uses TimerLib's performance counter to provide random numbers. | ||
// | ||
// Copyright (c) Microsoft Corporation. | ||
// | ||
// SPDX-License-Identifier: BSD-2-Clause-Patent | ||
// | ||
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#string STR_MODULE_ABSTRACT #language en-US "Instance of RNG Library" | ||
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#string STR_MODULE_DESCRIPTION #language en-US "BaseRng Library that uses the TimerLib to provide low-entropy random numbers" | ||
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/** @file | ||
BaseRng Library that uses the TimerLib to provide reasonably random numbers. | ||
Do not use this on a production system. | ||
Copyright (c) Microsoft Corporation. | ||
SPDX-License-Identifier: BSD-2-Clause-Patent | ||
**/ | ||
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#include <Base.h> | ||
#include <Library/BaseLib.h> | ||
#include <Library/DebugLib.h> | ||
#include <Library/TimerLib.h> | ||
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#define DEFAULT_DELAY_TIME_IN_MICROSECONDS 10 | ||
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/** | ||
Using the TimerLib GetPerformanceCounterProperties() we delay | ||
for enough time for the PerformanceCounter to increment. | ||
If the return value from GetPerformanceCounterProperties (TimerLib) | ||
is zero, this function will return 10 and attempt to assert. | ||
**/ | ||
STATIC | ||
UINT32 | ||
CalculateMinimumDecentDelayInMicroseconds ( | ||
VOID | ||
) | ||
{ | ||
UINT64 CounterHz; | ||
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// Get the counter properties | ||
CounterHz = GetPerformanceCounterProperties (NULL, NULL); | ||
// Make sure we won't divide by zero | ||
if (CounterHz == 0) { | ||
ASSERT(CounterHz != 0); // Assert so the developer knows something is wrong | ||
return DEFAULT_DELAY_TIME_IN_MICROSECONDS; | ||
} | ||
// Calculate the minimum delay based on 1.5 microseconds divided by the hertz. | ||
// We calculate the length of a cycle (1/CounterHz) and multiply it by 1.5 microseconds | ||
// This ensures that the performance counter has increased by at least one | ||
return (UINT32)(MAX (DivU64x64Remainder (1500000,CounterHz, NULL), 1)); | ||
} | ||
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/** | ||
Generates a 16-bit random number. | ||
if Rand is NULL, then ASSERT(). | ||
@param[out] Rand Buffer pointer to store the 16-bit random value. | ||
@retval TRUE Random number generated successfully. | ||
@retval FALSE Failed to generate the random number. | ||
**/ | ||
BOOLEAN | ||
EFIAPI | ||
GetRandomNumber16 ( | ||
OUT UINT16 *Rand | ||
) | ||
{ | ||
UINT32 Index; | ||
UINT8 *RandPtr; | ||
UINT32 DelayInMicroSeconds; | ||
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ASSERT (Rand != NULL); | ||
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if (Rand == NULL) { | ||
return FALSE; | ||
} | ||
DelayInMicroSeconds = CalculateMinimumDecentDelayInMicroseconds (); | ||
RandPtr = (UINT8*)Rand; | ||
// Get 2 bytes of random ish data | ||
for (Index = 0; Index < sizeof(UINT16); Index ++) { | ||
*RandPtr = (UINT8)(GetPerformanceCounter () & 0xFF); | ||
// Delay to give the performance counter a chance to change | ||
MicroSecondDelay (DelayInMicroSeconds); | ||
RandPtr++; | ||
} | ||
return TRUE; | ||
} | ||
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/** | ||
Generates a 32-bit random number. | ||
if Rand is NULL, then ASSERT(). | ||
@param[out] Rand Buffer pointer to store the 32-bit random value. | ||
@retval TRUE Random number generated successfully. | ||
@retval FALSE Failed to generate the random number. | ||
**/ | ||
BOOLEAN | ||
EFIAPI | ||
GetRandomNumber32 ( | ||
OUT UINT32 *Rand | ||
) | ||
{ | ||
UINT32 Index; | ||
UINT8 *RandPtr; | ||
UINT32 DelayInMicroSeconds; | ||
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ASSERT (Rand != NULL); | ||
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if (NULL == Rand) { | ||
return FALSE; | ||
} | ||
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RandPtr = (UINT8 *) Rand; | ||
DelayInMicroSeconds = CalculateMinimumDecentDelayInMicroseconds (); | ||
// Get 4 bytes of random ish data | ||
for (Index = 0; Index < sizeof(UINT32); Index ++) { | ||
*RandPtr = (UINT8)(GetPerformanceCounter () & 0xFF); | ||
// Delay to give the performance counter a chance to change | ||
MicroSecondDelay (DelayInMicroSeconds); | ||
RandPtr++; | ||
} | ||
return TRUE; | ||
} | ||
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/** | ||
Generates a 64-bit random number. | ||
if Rand is NULL, then ASSERT(). | ||
@param[out] Rand Buffer pointer to store the 64-bit random value. | ||
@retval TRUE Random number generated successfully. | ||
@retval FALSE Failed to generate the random number. | ||
**/ | ||
BOOLEAN | ||
EFIAPI | ||
GetRandomNumber64 ( | ||
OUT UINT64 *Rand | ||
) | ||
{ | ||
UINT32 Index; | ||
UINT8 *RandPtr; | ||
UINT32 DelayInMicroSeconds; | ||
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ASSERT (Rand != NULL); | ||
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if (NULL == Rand) { | ||
return FALSE; | ||
} | ||
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RandPtr = (UINT8 *)Rand; | ||
DelayInMicroSeconds = CalculateMinimumDecentDelayInMicroseconds (); | ||
// Get 8 bytes of random ish data | ||
for (Index = 0; Index < sizeof(UINT64); Index ++) { | ||
*RandPtr = (UINT8)(GetPerformanceCounter () & 0xFF); | ||
// Delay to give the performance counter a chance to change | ||
MicroSecondDelay (DelayInMicroSeconds); | ||
RandPtr++; | ||
} | ||
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return TRUE; | ||
} | ||
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/** | ||
Generates a 128-bit random number. | ||
if Rand is NULL, then ASSERT(). | ||
@param[out] Rand Buffer pointer to store the 128-bit random value. | ||
@retval TRUE Random number generated successfully. | ||
@retval FALSE Failed to generate the random number. | ||
**/ | ||
BOOLEAN | ||
EFIAPI | ||
GetRandomNumber128 ( | ||
OUT UINT64 *Rand | ||
) | ||
{ | ||
ASSERT (Rand != NULL); | ||
// This should take around 80ms | ||
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// Read first 64 bits | ||
if (!GetRandomNumber64 (Rand)) { | ||
return FALSE; | ||
} | ||
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// Read second 64 bits | ||
return GetRandomNumber64 (++Rand); | ||
} |
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