> The chain merging data is interesting. I see from the data below
> that the percentage of chains merged starts at 5% and then decreases
> linearly with the number of start values. The interesting thing is
> this:
> (vertical axis: % of chains lost, horizontal axis: chains left)
> screenshot of graph
> 
> I clearly see two lines. It appears that round functions 10, 14, 17,
> 21, 24, 28 and 31 (+/- 1) generate 0.5% less chain mergers. Do we
> have any clue why? Do they share a common bit value, or have a
> certain number of bits? Could you reconstruct the xor patterns for
> the 32 rounds, Sacha?

advance was 307232, second column is numbits==1 count
the only pattern i see is that the rounds with less chain mergers are
evenly spaced (ignoring round 1 - 10)

The values seem pretty prng to me. Probably just random fluctuation with
some influence on the next few rounds which restore the balance again.

2       26 39894c217a0103d7 (corresponds with the change between line 1 and 2
                             in the cited mail below)
3       24 e1ba888001e4d846
4       38 cb4caa7fecb9d16e
5       33 4c85f57e646611db
6       27 86011c6836045ef7
7       31 25e5fe857594042d
8       23 e0a1e00c94a39038
9       39 d10cdf47ad3ecdfd
10      23 14419070b2a619c1
11      29 2528cbe0974487a7
12      29 eb4c42d3885e3056
13      27 2c8d032fa00f28d6
14      28 26d0d1081f654d56
15      33 cf051426d32e97de
16      23 268920cf2111848e
17      33 c8bf942585591ef6
18      27 683aa0e50f4dc430
19      29 85cf17a8609bd122
20      23 032700c2533017a9
21      30 d1def48ea02e00d6
22      31 1e840ef31c1df554
23      32 c0137443fae91fe8
24      31 be66851b891dde08
25      28 280809b7bdea8d24
26      32 472733e1083cd3f5
27      29 7ddc0ac425912b1c
28      37 4abb1ad0e4d76bfd
29      36 de5bab07b94ba3ca
30      31 8a74eab16ac4395c
31      37 958b3eb1bad1eb37
32      28 b588a2bb4b1c2861
33      32 d5a9265ccbf8424e


the final chain count is:
32      cannot reconstruct
33      416172330

> 
> (equations are:
> y = 4.5613 * 10-9 x + 0.1163
> y = 3.937 * 10-9 x + 0.0581)
> 
> And if you could find the time to do it, I would really like to see
> the same table but then for the 100-forward case. I hope to relate
> some real-world data to the statistics derived above.
> 

sure. some more debugging and 3 days to build the table.
i hope you do not mean exactly the same table, but the same layout,
different advance, different start values, cause then i would have
to find the seed that mersenne twistered the start values again ;)

> 
> 
> On 1/12/10 12:58 AM, sascha wrote:
> >For a 32 rounds table with 1024*1024*1024 start values:
> >1  1073741823
> >2  1023438982
> >3  976087268
> >4  932768763
> >5  893795050
> >6  857258423
> >7  824594686
> >8  793842630
> >9  764984529
> >10 742264968
> >11 717542086
> >12 693794500
> >13 671348674
> >14 653519282
> >15 633911863
> >16 615705741
> >17 600811372
> >18 584022929
> >19 567966279
> >20 553038610
> >21 541126688
> >22 527714176
> >23 514813648
> >24 504121909
> >25 492442040
> >26 480922764
> >27 469931269
> >28 461146395
> >29 451036696
> >30 441442433
> >31 433670029
> >32 ?
> >33 ?
> >
> >sum: 20.5 Grounds
> >(instead of 30 Grounds)
> >
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