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- /** @file
- Support routines for RDRAND instruction access.
- Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
- (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
- SPDX-License-Identifier: BSD-2-Clause-Patent
- **/
- #include <Library/RngLib.h>
- #include "RdRand.h"
- #include "AesCore.h"
- /**
- Calls RDRAND to fill a buffer of arbitrary size with random bytes.
- @param[in] Length Size of the buffer, in bytes, to fill with.
- @param[out] RandBuffer Pointer to the buffer to store the random result.
- @retval EFI_SUCCESS Random bytes generation succeeded.
- @retval EFI_NOT_READY Failed to request random bytes.
- **/
- EFI_STATUS
- EFIAPI
- RdRandGetBytes (
- IN UINTN Length,
- OUT UINT8 *RandBuffer
- )
- {
- BOOLEAN IsRandom;
- UINT64 TempRand[2];
- while (Length > 0) {
- IsRandom = GetRandomNumber128 (TempRand);
- if (!IsRandom) {
- return EFI_NOT_READY;
- }
- if (Length >= sizeof (TempRand)) {
- WriteUnaligned64 ((UINT64*)RandBuffer, TempRand[0]);
- RandBuffer += sizeof (UINT64);
- WriteUnaligned64 ((UINT64*)RandBuffer, TempRand[1]);
- RandBuffer += sizeof (UINT64);
- Length -= sizeof (TempRand);
- } else {
- CopyMem (RandBuffer, TempRand, Length);
- Length = 0;
- }
- }
- return EFI_SUCCESS;
- }
- /**
- Creates a 128bit random value that is fully forward and backward prediction resistant,
- suitable for seeding a NIST SP800-90 Compliant, FIPS 1402-2 certifiable SW DRBG.
- This function takes multiple random numbers through RDRAND without intervening
- delays to ensure reseeding and performs AES-CBC-MAC over the data to compute the
- seed value.
- @param[out] SeedBuffer Pointer to a 128bit buffer to store the random seed.
- @retval EFI_SUCCESS Random seed generation succeeded.
- @retval EFI_NOT_READY Failed to request random bytes.
- **/
- EFI_STATUS
- EFIAPI
- RdRandGetSeed128 (
- OUT UINT8 *SeedBuffer
- )
- {
- EFI_STATUS Status;
- UINT8 RandByte[16];
- UINT8 Key[16];
- UINT8 Ffv[16];
- UINT8 Xored[16];
- UINT32 Index;
- UINT32 Index2;
- //
- // Chose an arbitrary key and zero the feed_forward_value (FFV)
- //
- for (Index = 0; Index < 16; Index++) {
- Key[Index] = (UINT8) Index;
- Ffv[Index] = 0;
- }
- //
- // Perform CBC_MAC over 32 * 128 bit values, with 10us gaps between 128 bit value
- // The 10us gaps will ensure multiple reseeds within the HW RNG with a large design margin.
- //
- for (Index = 0; Index < 32; Index++) {
- MicroSecondDelay (10);
- Status = RdRandGetBytes (16, RandByte);
- if (EFI_ERROR (Status)) {
- return Status;
- }
- //
- // Perform XOR operations on two 128-bit value.
- //
- for (Index2 = 0; Index2 < 16; Index2++) {
- Xored[Index2] = RandByte[Index2] ^ Ffv[Index2];
- }
- AesEncrypt (Key, Xored, Ffv);
- }
- for (Index = 0; Index < 16; Index++) {
- SeedBuffer[Index] = Ffv[Index];
- }
- return EFI_SUCCESS;
- }
- /**
- Generate high-quality entropy source through RDRAND.
- @param[in] Length Size of the buffer, in bytes, to fill with.
- @param[out] Entropy Pointer to the buffer to store the entropy data.
- @retval EFI_SUCCESS Entropy generation succeeded.
- @retval EFI_NOT_READY Failed to request random data.
- **/
- EFI_STATUS
- EFIAPI
- RdRandGenerateEntropy (
- IN UINTN Length,
- OUT UINT8 *Entropy
- )
- {
- EFI_STATUS Status;
- UINTN BlockCount;
- UINT8 Seed[16];
- UINT8 *Ptr;
- Status = EFI_NOT_READY;
- BlockCount = Length / 16;
- Ptr = (UINT8 *)Entropy;
- //
- // Generate high-quality seed for DRBG Entropy
- //
- while (BlockCount > 0) {
- Status = RdRandGetSeed128 (Seed);
- if (EFI_ERROR (Status)) {
- return Status;
- }
- CopyMem (Ptr, Seed, 16);
- BlockCount--;
- Ptr = Ptr + 16;
- }
- //
- // Populate the remained data as request.
- //
- Status = RdRandGetSeed128 (Seed);
- if (EFI_ERROR (Status)) {
- return Status;
- }
- CopyMem (Ptr, Seed, (Length % 16));
- return Status;
- }
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