CryptRand.c

Go to the documentation of this file.

 
#include "InternalCryptLib.h"
#include <openssl/rand.h>
#include <openssl/evp.h>
 
//
// Default seed for UEFI Crypto Library
//
CONST UINT8  DefaultSeed[] = "UEFI Crypto Library default seed";
 
BOOLEAN
EFIAPI
RandomSeed (
  IN  CONST  UINT8  *Seed  OPTIONAL,
  IN  UINTN         SeedSize
  )
{
  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 {
    RAND_seed (DefaultSeed, sizeof (DefaultSeed));
  }
 
  if (RAND_status () == 1) {
    return TRUE;
  }
 
  return FALSE;
}
 
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;
}