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/** @file
Provides an implementation of the library class RngLib that uses the Rng protocol.
Copyright (c) 2023, Arm Limited. All rights reserved.
Copyright (c) Microsoft Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Uefi.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/DebugLib.h>
#include <Library/RngLib.h>
#include <Protocol/Rng.h>
/**
Routine Description:
Generates a random number via the NIST
800-9A algorithm. Refer to
http://csrc.nist.gov/groups/STM/cavp/documents/drbg/DRBGVS.pdf
for more information.
@param[out] Buffer Buffer to receive the random number.
@param[in] BufferSize Number of bytes in Buffer.
@retval EFI_SUCCESS or underlying failure code.
**/
STATIC
EFI_STATUS
GenerateRandomNumberViaNist800Algorithm (
OUT UINT8 *Buffer,
IN UINTN BufferSize
)
{
EFI_STATUS Status;
EFI_RNG_PROTOCOL *RngProtocol;
RngProtocol = NULL;
if (Buffer == NULL) {
DEBUG ((DEBUG_ERROR, "%a: Buffer == NULL.\n", __func__));
return EFI_INVALID_PARAMETER;
}
Status = gBS->LocateProtocol (&gEfiRngProtocolGuid, NULL, (VOID **)&RngProtocol);
if (EFI_ERROR (Status) || (RngProtocol == NULL)) {
DEBUG ((DEBUG_ERROR, "%a: Could not locate RNG prototocol, Status = %r\n", __func__, Status));
return Status;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmSp80090Ctr256Guid, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm CTR-256 - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmSp80090Hmac256Guid, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm HMAC-256 - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmSp80090Hash256Guid, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm Hash-256 - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmRaw, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm Raw - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
// If all the other methods have failed, use the default method from the RngProtocol
Status = RngProtocol->GetRNG (RngProtocol, NULL, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm default - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
// If we get to this point, we have failed
DEBUG ((DEBUG_ERROR, "%a: GetRNG() failed, staus = %r\n", __func__, Status));
return Status;
}// GenerateRandomNumberViaNist800Algorithm()
/**
Generates a 16-bit random number.
if Rand is NULL, return FALSE.
@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
)
{
EFI_STATUS Status;
if (Rand == NULL) {
return FALSE;
}
Status = GenerateRandomNumberViaNist800Algorithm ((UINT8 *)Rand, sizeof (UINT16));
if (EFI_ERROR (Status)) {
return FALSE;
}
return TRUE;
}
/**
Generates a 32-bit random number.
if Rand is NULL, return FALSE.
@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
)
{
EFI_STATUS Status;
if (Rand == NULL) {
return FALSE;
}
Status = GenerateRandomNumberViaNist800Algorithm ((UINT8 *)Rand, sizeof (UINT32));
if (EFI_ERROR (Status)) {
return FALSE;
}
return TRUE;
}
/**
Generates a 64-bit random number.
if Rand is NULL, return FALSE.
@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
)
{
EFI_STATUS Status;
if (Rand == NULL) {
return FALSE;
}
Status = GenerateRandomNumberViaNist800Algorithm ((UINT8 *)Rand, sizeof (UINT64));
if (EFI_ERROR (Status)) {
return FALSE;
}
return TRUE;
}
/**
Generates a 128-bit random number.
if Rand is NULL, return FALSE.
@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
)
{
EFI_STATUS Status;
if (Rand == NULL) {
return FALSE;
}
Status = GenerateRandomNumberViaNist800Algorithm ((UINT8 *)Rand, 2 * sizeof (UINT64));
if (EFI_ERROR (Status)) {
return FALSE;
}
return TRUE;
}
/**
Get a GUID identifying the RNG algorithm implementation.
@param [out] RngGuid If success, contains the GUID identifying
the RNG algorithm implementation.
@retval EFI_SUCCESS Success.
@retval EFI_UNSUPPORTED Not supported.
@retval EFI_INVALID_PARAMETER Invalid parameter.
**/
EFI_STATUS
EFIAPI
GetRngGuid (
GUID *RngGuid
)
{
/* It is not possible to know beforehand which Rng algorithm will
* be used by this library.
* This API is mainly used by RngDxe. RngDxe relies on the RngLib.
* The RngLib|DxeRngLib.inf implementation locates and uses an installed
* EFI_RNG_PROTOCOL.
* It is thus not possible to have both RngDxe and RngLib|DxeRngLib.inf.
* and it is ok not to support this API.
*/
return EFI_UNSUPPORTED;
}
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