/** @file | |
Pseudorandom Number Generator Wrapper Implementation over OpenSSL. | |
Copyright (c) 2012 - 2013, Intel Corporation. All rights reserved.<BR> | |
This program and the accompanying materials | |
are licensed and made available under the terms and conditions of the BSD License | |
which accompanies this distribution. The full text of the license may be found at | |
http://opensource.org/licenses/bsd-license.php | |
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, | |
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. | |
**/ | |
#include "InternalCryptLib.h" | |
#include <openssl/rand.h> | |
#include <openssl/evp.h> | |
#include <Library/PrintLib.h> | |
/** | |
Sets up the seed value for the pseudorandom number generator. | |
This function sets up the seed value for the pseudorandom number generator. | |
If Seed is not NULL, then the seed passed in is used. | |
If Seed is NULL, then default seed is used. | |
@param[in] Seed Pointer to seed value. | |
If NULL, default seed is used. | |
@param[in] SeedSize Size of seed value. | |
If Seed is NULL, this parameter is ignored. | |
@retval TRUE Pseudorandom number generator has enough entropy for random generation. | |
@retval FALSE Pseudorandom number generator does not have enough entropy for random generation. | |
**/ | |
BOOLEAN | |
EFIAPI | |
RandomSeed ( | |
IN CONST UINT8 *Seed OPTIONAL, | |
IN UINTN SeedSize | |
) | |
{ | |
CHAR8 DefaultSeed[128]; | |
if (SeedSize > INT_MAX) { | |
return FALSE; | |
} | |
// | |
// The software PRNG implementation built in OpenSSL depends on message digest algorithm. | |
// Make sure SHA-1 digest algorithm is available here. | |
// | |
if (EVP_add_digest (EVP_sha1 ()) == 0) { | |
return FALSE; | |
} | |
// | |
// Seed the pseudorandom number generator with user-supplied value. | |
// NOTE: A cryptographic PRNG must be seeded with unpredictable data. | |
// | |
if (Seed != NULL) { | |
RAND_seed (Seed, (UINT32) SeedSize); | |
} else { | |
// | |
// Retrieve current time. | |
// | |
AsciiSPrint ( | |
DefaultSeed, | |
sizeof (DefaultSeed), | |
"UEFI Crypto Library default seed (%ld)", | |
AsmReadTsc () | |
); | |
RAND_seed (DefaultSeed, sizeof (DefaultSeed)); | |
} | |
if (RAND_status () == 1) { | |
return TRUE; | |
} | |
return FALSE; | |
} | |
/** | |
Generates a pseudorandom byte stream of the specified size. | |
If Output is NULL, then return FALSE. | |
@param[out] Output Pointer to buffer to receive random value. | |
@param[in] Size Size of randome bytes to generate. | |
@retval TRUE Pseudorandom byte stream generated successfully. | |
@retval FALSE Pseudorandom number generator fails to generate due to lack of entropy. | |
**/ | |
BOOLEAN | |
EFIAPI | |
RandomBytes ( | |
OUT UINT8 *Output, | |
IN UINTN Size | |
) | |
{ | |
// | |
// Check input parameters. | |
// | |
if (Output == NULL || Size > INT_MAX) { | |
return FALSE; | |
} | |
// | |
// Generate random data. | |
// | |
if (RAND_bytes (Output, (UINT32) Size) != 1) { | |
return FALSE; | |
} | |
return TRUE; | |
} |