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