rnd.c

   1 #include <sys/types.h>
   2 #include <sys/stat.h>
   3 #include <fcntl.h>
   4 #include <unistd.h>
   5
   6 #include "rnd.h"
   7 #include "die.h"
   8 #include "ioexact.h"
   9 #include "ioops.h"
  10
  11 static int fdw = -1;
  12
  13 static void randombytes_weak(unsigned char *x, size_t xlen)
  14 {
  15         int ret;
  16
  17         if (fdw == -1) {
  18                 for (;;) {
  19                         fdw = open(LOW_ENTROPY_SOURCE, O_RDONLY);
  20                         if (fdw != -1)
  21                                 break;
  22                         sleep(1);
  23                 }
  24         }
  25
  26         while (xlen > 0) {
  27                 if (xlen < 1048576)
  28                         ret = xlen;
  29                 else
  30                         ret = 1048576;
  31
  32                 ret = read(fdw, x, ret);
  33                 if (ret < 1) {
  34                         sleep(1);
  35                         continue;
  36                 }
  37
  38                 x += ret;
  39                 xlen -= ret;
  40         }
  41 }
  42
  43 static void randombytes_strong(unsigned char *x, size_t xlen)
  44 {
  45         int fds, ret;
  46
  47         fds = open_or_die(HIG_ENTROPY_SOURCE, O_RDONLY);
  48
  49         ret = read_exact(fds, x, xlen, 0);
  50         if (ret != (int) xlen)
  51                 panic("Error reading from entropy source!\n");
  52
  53         close(fds);
  54 }
  55
  56 int secrand(void)
  57 {
  58         int ret;
  59
  60         randombytes_weak((void *) &ret, sizeof(ret));
  61
  62         return ret;
  63 }
  64
  65 void gen_key_bytes(unsigned char *area, size_t len)
  66 {
  67         randombytes_strong(area, len);
  68 }