41 entries in 0.378s
: ( modular exp
onentiation is , in all operations which feature it )
: BingoBoingo: to nitpick, s/in Barrett's Modular
Reduction/in modular exp
onentiation/ , koch dun use barrett ( he uses montgomery, which dies on even numbers, lol )
: user of pcode never has to manually consider memory, so long as he knows how much stack to instantiate it with ( e.g. for modular exp
onentiation, you need 3 FZ worth of stack ) , and it properly eggogs if you mismeasure.
: Turns out, Kochs pile of shit, despite eschewing constant time arithmetic, and being implemented in Overflowandcrashlang
loses the footrace, when given a full-width modular exp
onentiation (i.e. one where it cannot cheat by skipping over leading zeroes.)
: hey NoSatoshisHear -- you say you read the ffa series ? in what order of complexity does modular exp
onentiation run ?
: modular exp
is intrinsically costlier , at least on pc iron, than the idjit rotorization used in symmetrics
: diana_coman: ffa arithmetic stack is theoretically available. however until i have barrett reduction going, it's a ~30 second modular exp
onentiation ( i.e. per rsa op )
: is it or is it not true a modular exp
onentiation in current gpg takes, on your chosen machine, 0.26 seconds.
: Logged on 2017-09-16 15:31 asciilifeform: in other olds ( i dun think i posted this measurement ) the NAIVE modular exp
onentiator takes 51.3 seconds per 4096b a*b mod m , on the 'standard' test box
: when bitness is B, a modular exp
onentiation takes B mod-muls and B mod-squares, each of which produces a 2B-wide item that gets div'd . that's 2B 2B-wide divisions.
: in other olds ( i dun think i posted this measurement ) the NAIVE modular exp
onentiator takes 51.3 seconds per 4096b a*b mod m , on the 'standard' test box ☟︎
: and it is not only O(N^3), but when you modularly exp
onentiate it actually gets done B times, and not to B-sized inputs, but 2B ( because we have a multiply and then also a square, in each step of the B-step modular exp
onentiation bitwise )
: ( the rsa operation, the one and only, is modular exp
onentiation. but it is made trivially from modular
multiplication . )
: asciilifeform amusingly, the guy complains about the modular exp
onentiation not being constant time. maybe write to him ask where he ever saw a sane algo ?
: meanwhile from literature search, every article ever, apparently, written re 'constant time modular exp
onentiation' proposes... tables
: aite, nao all asciilifeform needs is a constantspacetime MODULAR exp
algo that can be exp
ressed with the mux primitive
: the 'release modular exp
onentiation result after time T' is an armoured propeller.
: also: Complete break of RSA-1024 as implemented in Libgcrypt https://eprint.iacr.org/2017/627.pdf,
"And 13% of RSA-2048 keys. Whoopsie!", "The new bit is showing that LtR sliding windows are a Very Bad Choice for modular exp
onentiation. Very nice."
: this means ALL ciphertext is the output of rsa modular exp
: asciilifeform i imagine he means that it overflow between the exp
and the modular
: what i don't yet have is a fixed-time modular exp
: does anybody have a favourite constant-time modular
: for some peculiar reason, everybody else (afaik) who implemented a bignumtron, only did this (or claimed, at any rate) for modular exp
onentiation -- but not for its subcomponent ops
: the thing is called modular exp
onentiation you know :D
: this comes with the territory of 'naked' register. in ada you have to exp
licitly ask for this horror, it is called 'modular
type'. all c types are it.
: 'If one tries to calculate a modular exp
onentiation with the base equal to the modulus (a^b mod a, code) it would return an error. If one tries to calculate a modular exp
onentiation with the base zero (0^b mod a, code) it would crash with an invalid free operation, potentially leading to memory corruption.'
: when done correctly - no. we don't sit here and argue about how the modular exp
onentiations came out.
: Logged on 23-12-2015 22:29:00; ascii_field: thestringpuller: be grateful that you don't have to modular
onentiate by hand.
: thestringpuller: be grateful that you don't have to modular
onentiate by hand. ☟︎
: sane people understand enough to wish for their rsa modular exp
onentiations to NOT HAPPEN UNDER WINBLOWZ
: prototype is essentially an 'rpn calculator' where you can push bignums on the stack and instruction 0x01 --> 'pop two, multiply, push back' or 0x70 --> modular
: it is, in principle, possible for dr. evil's cpu to recognize when, e.g, given version of gpg is in the process of taking the modular exp
: good thing my mattress is modular
, i can easily exp
and to bed more women
: cancellations deep inside GnuPG’s modular exp
onentiation algorithm. This causes the special value