mirror of
https://github.com/servalproject/serval-dna.git
synced 2024-12-22 14:32:25 +00:00
75 lines
1.9 KiB
C
75 lines
1.9 KiB
C
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "crypto_uint64.h"
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#include "uint64_pack.h"
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#include "uint64_unpack.h"
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#include "savesync.h"
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#include "open.h"
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#include "load.h"
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#include "randombytes.h"
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#include "safenonce.h"
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#include "crypto_block.h"
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#if crypto_block_BYTES != 16
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error!
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#endif
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#if crypto_block_KEYBYTES != 32
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error!
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#endif
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/*
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Output: 128-bit nonce y[0],...,y[15].
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Reads and writes existing 8-byte file ".expertsonly/noncecounter",
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locked via existing 1-byte file ".expertsonly/lock".
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Also reads existing 32-byte file ".expertsonly/noncekey".
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Not thread-safe.
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Invariants:
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This process is free to use counters that are >=counterlow and <counterhigh.
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The 8-byte file contains a counter that is safe to use and >=counterhigh.
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XXX: should rewrite file in background, rather than briefly pausing
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*/
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static crypto_uint64 counterlow = 0;
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static crypto_uint64 counterhigh = 0;
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static unsigned char flagkeyloaded = 0;
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static unsigned char noncekey[32];
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static unsigned char data[16];
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int safenonce(unsigned char *y,int flaglongterm)
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{
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if (!flagkeyloaded) {
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int fdlock;
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fdlock = open_lock(".expertsonly/lock");
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if (fdlock == -1) return -1;
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if (load(".expertsonly/noncekey",noncekey,sizeof noncekey) == -1) { close(fdlock); return -1; }
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close(fdlock);
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flagkeyloaded = 1;
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}
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if (counterlow >= counterhigh) {
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int fdlock;
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fdlock = open_lock(".expertsonly/lock");
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if (fdlock == -1) return -1;
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if (load(".expertsonly/noncecounter",data,8) == -1) { close(fdlock); return -1; }
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counterlow = uint64_unpack(data);
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if (flaglongterm)
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counterhigh = counterlow + 1048576;
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else
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counterhigh = counterlow + 1;
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uint64_pack(data,counterhigh);
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if (savesync(".expertsonly/noncecounter",data,8) == -1) { close(fdlock); return -1; }
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close(fdlock);
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}
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randombytes(data + 8,8);
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uint64_pack(data,counterlow++);
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crypto_block(y,data,noncekey);
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return 0;
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}
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