N Factor

Yacoin adjusts the N factor of the hash using a formula which is based on block time.

Dates

N Factor change dates.

N Factor	N	UTC Time	Unix Time
4	16	2013-05-08 06:33:20	1367991200
5	32	2013-05-14 08:11:28	1368515488
6	64	2013-05-17 09:00:32	1368777632
7	128	2013-05-20 09:49:36	1369039776
8	256	2013-05-29 12:16:48	1369826208
9	512	2013-06-01 13:05:52	1370088352
10	1024	2013-06-25 19:38:24	1372185504
11	2048	2013-07-07 22:54:40	1373234080
12	4096	2013-08-13 08:43:28	1376379808
13	8192	2013-09-30 21:48:32	1380574112
14	16384	2013-11-18 09:53:36	1384768416
15	32768	2014-05-31 15:13:52	1401545632
16	65536	2014-09-05 17:24:00	1409934240
17	131072	2015-06-23 23:54:24	1435100064
18	262144	2016-07-16 08:34:56	1468654496
19	524288	2017-08-08 17:15:28	1502208928
20	1048576	2020-10-16 19:17:04	1602872224
21	2097152	2021-11-09 02:57:36	1636426656
22	4194304	2030-05-13 01:21:52	1904862112
23	8388608	2038-11-13 21:46:08	2173297568
24	16777216	2047-05-17 20:10:24	2441733024
25	33554432	2072-11-22 11:23:12	3247039392
26	67108864	2081-05-26 09:47:28	3515474848
27	134217728	2149-06-14 13:01:36	5662958496
28	268435456	2183-06-24 02:38:40	6736700320
29	536870912	2285-07-21 19:29:52	9957925792
30	1073741824	2421-08-28 01:58:08	14252893088

Algorithm

// yacoin: increasing Nfactor gradually
const unsigned char minNfactor = 4;
const unsigned char maxNfactor = 30;
int64 nChainStartTime = 1367991200;

unsigned char GetNfactor(int64 nTimestamp) {
    int l = 0;

    if (nTimestamp <= nChainStartTime)
        return 4;

    int64 s = nTimestamp - nChainStartTime;
    while ((s >> 1) > 3) {
      l += 1;
      s >>= 1;
    }

    s &= 3;

    int n = (l * 170 + s * 25 - 2320) / 100;

    if (n < 0) n = 0;

    if (n > 255)
        printf("GetNfactor(%d) - something wrong(n == %d)\n", nTimestamp, n);

    unsigned char N = (unsigned char)n;

    return min(max(N, minNfactor), maxNfactor);
}