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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "crypto_uint64.h"
#include "uint64_pack.h"
#include "uint64_unpack.h"
#include "savesync.h"
#include "open.h"
#include "load.h"
#include "randombytes.h"
#include "safenonce.h"
#include "crypto_block.h"
#if crypto_block_BYTES != 16
error!
#endif
#if crypto_block_KEYBYTES != 32
error!
#endif
/*
Output: 128-bit nonce y[0],...,y[15].
Reads and writes existing 8-byte file ".expertsonly/noncecounter",
locked via existing 1-byte file ".expertsonly/lock".
Also reads existing 32-byte file ".expertsonly/noncekey".
Not thread-safe.
Invariants:
This process is free to use counters that are >=counterlow and <counterhigh.
The 8-byte file contains a counter that is safe to use and >=counterhigh.
XXX: should rewrite file in background, rather than briefly pausing
*/
static crypto_uint64 counterlow = 0;
static crypto_uint64 counterhigh = 0;
static unsigned char flagkeyloaded = 0;
static unsigned char noncekey[32];
static unsigned char data[16];
int safenonce(unsigned char *y,int flaglongterm)
{
if (!flagkeyloaded) {
int fdlock;
fdlock = open_lock(".expertsonly/lock");
if (fdlock == -1) return -1;
if (load(".expertsonly/noncekey",noncekey,sizeof noncekey) == -1) { close(fdlock); return -1; }
close(fdlock);
flagkeyloaded = 1;
}
if (counterlow >= counterhigh) {
int fdlock;
fdlock = open_lock(".expertsonly/lock");
if (fdlock == -1) return -1;
if (load(".expertsonly/noncecounter",data,8) == -1) { close(fdlock); return -1; }
counterlow = uint64_unpack(data);
if (flaglongterm)
counterhigh = counterlow + 1048576;
else
counterhigh = counterlow + 1;
uint64_pack(data,counterhigh);
if (savesync(".expertsonly/noncecounter",data,8) == -1) { close(fdlock); return -1; }
close(fdlock);
}
randombytes(data + 8,8);
uint64_pack(data,counterlow++);
crypto_block(y,data,noncekey);
return 0;
}
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