#asciilifeform | 2020-11-17

feedbot: http://mvdstandard.net/2020/11/rocha-under-alert-for-portuguese-man-o-war/ << The Montevideo Standard -- Rocha Under Alert For Portuguese Man O' War

cgra: asciilifeform: a 256-bit peh tape like ".1 .FF LS .1 .3 MX" will bomb on me at here.

cgra: i haven't followed exactly a linear learning schedule, so some of the earlier chapters are somewhat unfamiliar to me... but, the reason appears to be this optimization.

cgra: say, for example: if X := 2**255 and M := 2**255 - 1, X - Q would end up negative (as that tape does in my case), because of the optimization.

cgra: as a side note, a 256-bit test tape "10k_shots_256bit_ffa_slid_rnd.tape" also bombs the same way on me

asciilifeform: cgra: thanks, will look.

asciilifeform: cgra: your example indeed bombs. the test tape doesn't, tho, interestingly (are you sure you linked the right one?)

cgra: i'll re-check

asciilifeform: ty

cgra: sha256sum of the test tape in q is "b6388e30fb881ebd7a37bf45fb07003e0420f2c923495dfc60c0705f22cca6a2"

asciilifeform: aa there we go.

asciilifeform: does bomb (initially when tried i did not specify sufficient run life)

asciilifeform: ... apparently did the same in the orig. bash script which ran this tape !

cgra: hehe :)

asciilifeform: ty for the tip-off, cgra . loox like ch14 will need same treatment as ch15 earlier.

cgra: np, glad i could provide finally some useful input

asciilifeform: cgra: most useful external input to date, in fact.

asciilifeform: the bomb in 15 i had to find on my own, despite certain pompous maffs phd supposedly 'read' and signed.

cgra: i dunno if i'd have spotted the issue by walking through the physical bounds proof. i stumbled upon it while experimenting

asciilifeform: cgra: after the incident w/ 15, i've been rereading & reproving continuously ch21b/c since april !

asciilifeform: at some pt will finally release it... apparently later rather than sooner.

asciilifeform: !!rated cgra

deedbot: asciilifeform has not rated cgra.

asciilifeform: !!key cgra

deedbot: Not registered.

asciilifeform: hey cgra wouldja get in deedbot already , so i can rate you ?

cgra: asciilifeform: how much do you have currently half-complete material for ffa?

asciilifeform: cgra: just about all of it

asciilifeform: ( 21 is done, as is 22, only hashism is entirely unwritten yet )

cgra: right

asciilifeform will have to unravel 14 and rewrite all of the material thereof, will prolly take a while.

cgra: i've been delaying the wot registration, because i don't have a proper understanding of best realistic approach to it yet

asciilifeform: cgra: elaborate ?

asciilifeform will be back in ~40m

cgra: asciilifeform: i mean, i thought i'd learn some rsa etc first, to be able to decide what's 'good enough'. in case i have more choices avail than the current wot people had at their registration time

asciilifeform back

asciilifeform: cgra: atm trinque's wot system is strictly rsa, afaik.

trinque: cgra: yes, use an RSA key, and there are key-length discussions in the old logs to be found.

trinque: that said, don't fester too much about doing things "right" when the foundation itself is a pile of accidental crap.

trinque: when we've moved to asciilifeform's crypter for this, much more can be said about right.

trinque: as of now deedbot sits on a gnupg.

cgra: trinque: ok

asciilifeform: wb trinque

asciilifeform: $ticker btc usd

btcinfobot: Current BTC price in USD: $17599.51

asciilifeform: !w poll

watchglass: Polling 16 nodes...

watchglass: 205.134.172.26:8333 : Alive: (0.082s) V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Blocks=657380

watchglass: 205.134.172.27:8333 : Alive: (0.080s) V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Blocks=657380 (Operator: asciilifeform)

watchglass: 205.134.172.6:8333 : (172-6.core.ai.net) Alive: (0.135s) V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Blocks=657380

watchglass: 205.134.172.28:8333 : Alive: (0.023s) V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Return Addr=0.0.0.0:8333 Blocks=657213 (Operator: whaack)

watchglass: 71.114.46.209:8333 : (pool-71-114-46-209.washdc.fios.verizon.net) Alive: (0.103s) V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Blocks=657380 (Operator: asciilifeform)

watchglass: 176.9.59.199:8333 : Could not connect! (Operator: jurov)

watchglass: 205.134.172.4:8333 : (172-4.core.ai.net) Alive: (0.140s) V=70001 (/therealbitcoin.org:0.7.0.1/) Jumpers=0x1 (TRB-Compat.) Blocks=657380

watchglass: 54.39.156.171:8333 : (ns562940.ip-54-39-156.net) Alive: (0.115s) V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Blocks=657380

watchglass: 185.163.46.29:8333 : Violated BTC Protocol: Bad header length!

watchglass: 208.94.240.42:8333 : Alive: (0.167s) V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Blocks=657380

watchglass: 192.151.158.26:8333 : Alive: (0.183s) V=70001 (/therealbitcoin.org:0.7.0.1/) Jumpers=0x1 (TRB-Compat.) Blocks=657380

asciilifeform: cgra: pretty subtle mistake, btw. the proof aint wrong, per se -- Q <= X in all cases. and R in fact has at most Wm+2 bits. but in subtraction in step 5, it is necessary to add the carry to the result R, rather than bomb if carry != 0.

asciilifeform: in cgra's example, at step 5 :

snsabot: Logged on 2020-11-17 10:01:28 cgra: asciilifeform: a 256-bit peh tape like ".1 .FF LS .1 .3 MX" will bomb on me at here.

asciilifeform: x == 0x40000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

asciilifeform: q == 0x3FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

asciilifeform: x - q == 1 ; but what gets computed is X(1 .. Rl) - Q(1 .. Rl) , i.e. :

asciilifeform: 0x00000000000000000000000000000000000000000000000000000000000000000000000000000000 - 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

asciilifeform: which yields 0, and a carry (borrow) bit 1 .

asciilifeform: which is the actual answer, given as we know that q <= x, and did not bother running through entire subtraction (but only for the length req'd to obtain the max known bitness of R)

asciilifeform: will chew on ch14 for a while, but currently afaik that's the whole story here.