Sunday, February 26, 2017

[ryqubypz] Removing letters from the alphabet

Pairing some letters by phonetic similarity (usually voiced versus unvoiced consonants, inspired by Japanese hiragana) allows removing some letters from a small keyboard, adding one more key to signify using the alternate letter.

bp cj dt fv gk hw lr mn qx sz a e i o u y

Previously.

[grputrtr] Passenger only aircraft

Consider flying every flight as two planes: one for the people and another for the luggage.  This decreases the harm of bombs being placed in luggage.

Modify a plane to carry more people, no luggage.  Probably double decker.

[utbdzflf] Serving people who hate their jobs

An employee hates his or her job.  This makes unpleasant life for those who work with, or for, that employee.  That unpleasantness causes them to hate their jobs too.  This then causes feedback to the first employee who hates his or her job even more because of the unhappy people he or she has to work with.

How much does this happen?  Can the cycle be broken?

[vizxbugj] Garbage collect before OOM killing

Before the operating system starts killing processes when it is out of memory, consider signalling processes (somehow) to run their garbage collection now and release their freed memory back to the OS, assuming they are written in a garbage collected language.  Need some standardized method of signalling.

Instead of every process having its own private garbage collector, provide it as an operating system service.  This seems tricky, as each program may encode references differently.

Also consider signalling processes to do garbage collection when performance has gotten bad due to frequent swapping to virtual memory.  This might not be too effective because stuff sitting around waiting to be garbage collected probably sits quietly swapped out.  Doing garbage collection on them might even make things worse.

[fzozfmue] House burglary and gun ownership

Are house burglars more prevalent and more bold in areas with stricter gun control?  Need to control for the many other factors which could affect house burglars.

Inspired by the lock snapping vulnerability discovered and being frequently exploited in Britain, whereas many American home door locks are even less secure.

[hhqmupvg] Light and heavy punctuation

Punctuation can roughly be divided into two categories.

Light punctuation can replace space as a token separator: hyphen/dash.  Underbar in computer code.  Colon in time.  Period in DNS.

Heavy punctuation usually has a space on at least one side.

[jicgchtx] Cavalier and variations

The cavalier is a fairy chess piece that improves on the gryphon by correcting the gryphon's asymmetric retreat: the gryphon cannot exit the way it arrived.

(Is the cavalier actually an improvement?  Or does this peculiar feature of the gryphon make the game more interesting?)

The cavalier's move can be either a ferz move followed by an outward rook move or a rook move followed by an outward ferz.  The two possible paths prevent the asymmetric blocking possible with the gryphon.

The cavalier's range is slightly different from the gryphon because in its rook move, it must step at least one square.  However, a cavalier ferz compound does have the same range as a gryphon.

In terms of range, cavalier = gryphon - ferz.  We can also consider similar subtractions to sliding pieces: a rook minus wazir, bishop minus ferz, queen minus either or them, or queen minus king.  The intervening (subtracted) square must be empty.  If we want jumping, we can add that back in with alfil or dabbaba.  Jump and slide on the same move remains impossible though.  If it were possible, we'd have asymmetric retreat problems again.

These "minus sliders" are nice components to make compound pieces out of.  The abilities are disjoint.

A piece that makes one ferz then one wazir move, in either order, both outward, has the same range as a knight but requires at least one of the intervening squares to be empty.

[izyttmmm] Point particle pool

Instead of billiard balls being spheres undergoing perfectly elastic collisions, create a new game, probably virtual, in which the collisions are of point particles obeying an inverse square law of repulsion or attraction.

Incidentally, when distances are relatively large and all particles repel, the system behaves like billiard balls.

How should motion stop, providing a static state for the next player's move?  The particles never stop exerting force on each other.  Easiest is for time to stop (perhaps at a time point controlled by the player), at which point all velocities are set to zero.  On the next move, the player gets to set the velocity of the cue particle (ball) and start time moving forward again.

Much more ambitious: simulate electron and position collisions as in a particle accelerator: new particles can be created.  The inverse square law only applies at large distances.

Friday, February 24, 2017

[ralkzndf] Safe space and the War on Drugs

We clarify the parallels between "safe space", "consent culture", and the War on Drugs, responding to this comment on this old post:

Assuming the rules for "safe space" and "consent culture" are accompanied with punishments for breaking those rules, my suspicion is that those who will be on the receiving end of such punishments will again be the same minorities and marginalized classes disproportionately on the receiving end of punishments in the War on Drugs.

Two parts of the connection:

These marginalized groups are the ones that the privileged portion of society wants to see punished to the max.  They are "Them" (in Us versus Them); they are the Other.  Society (the privileged portion) does not ask for leniency when They are up for punishment like it asks for (and usually gets) when One Of Us is up for punishment.

Within these marginalized groups is a disproportionately large subset that society likes to deny opportunity, whether opportunities for legitimate jobs outside the illegal drug industry, or opportunities for social, romantic, or sexual interaction: "I don't want to be around this person."  Integral to a safe space violation or consent violation is someone saying "no", and many people choose to say "no" based on racial and social class prejudices.

[htnrbrdd] Expressive other hand

Hold a smart phone in one hand.  The other hand and arm is free to do all kinds of expressive motions: so much more than sliding a finger around a touch screen display.  The problem is how a sensor can detect those actions.

Inspired by musical conducting.

[hrzgkqno] Music bridging the culture gap

We have a very divided society where the sides are failing to communicate with each other.  Can music -- or more broadly, art -- bridge this communication gap, explaining one side's {position, ideas, culture} in a way the other side can relate?

Perhaps yes: this is the kind of thing which could be helped along by philanthropy, commissioning art with this goal of building bridges.  It is up to the artist the perhaps unenviable grunt work of learning "the other side" then perhaps the unenviable grunt work of figuring out how to communicate it to "our side".

Perhaps not: people consume the entertainment they like, that they agree with.  People hear in music what they want to hear, which might be different from what the musician is trying to say.

It seems highly likely this has already been tried, or done.  How has such music or art been received?

[stqcijwh] Quipu

Create a system of recording information using knots on a string, or multiple strings.  If desirable, reuse any ideas from Incan quipus, though most of that knowledge is lost.

Knots are neat because information is being recorded in topology, which is different from most other methods of recording information.  Consider how difficult it is to turn a knot into not-a-knot, or turning a left-handed knot into a right-handed one.  Compare that to the ease of altering information in other media: it typically requires only a local change.

Modern technology can create extremely durable fibers for long term preservation of information: which fibers should be used?  Knotting puts stress on a string.

Should the nature of the knot matter, e.g., size, type, or should it just be binary of whether there is a knot at a position or not?  A special type of string could be amenable to X-ray CAT scans which could decode the internal structure of a knot.  Specially colored fibers could allow 3D computer vision techniques to derive the type of knot just by examining its outer surface.

Modern technology can probably make knots at very precise locations on a string.

Intriguing is having the knots on loops of string as knot theory does it instead of straight segments.  We need some way of fusing the ends of a string (without a knot) -- many such ways exist -- or directly creating loops of string with knots on them (e.g., 3D printing).

Knots have an attractive feature that they can be read by touch, e.g. in low light environments or with failing eyesight.

[elbejrwh] Clouds as local key

Take a picture of some clouds outside and robustly derive a cryptographic key from them.  Broadcast some information encrypted with this key.

Anyone in the vicinity can take their own picture of the clouds, derive the same key, and decrypt.  Time passes, the clouds change shape, and the information becomes impossible to decrypt: it was ephemeral.  Attackers far away also cannot see the clouds.

How can one robustly derive the same key from pictures of clouds taken at slightly different points in time from slightly different vantage points?  The sky is big: how can the sender and receivers agree on which cloud?  Can weather satellites constantly recording every cloud defeat this?

What would this technology be useful for?

Are there other things like clouds which can serve as the basis for this kind of system?  We could artificially generate such a signal (previously).

Thursday, February 23, 2017

[lkzruaxs] Only high compression matters

One tends to use lossless data compression (text compression) on data that can be compressed a lot, for example log files or trace files.  For small amounts of compression, the slightly decreased bandwidth or increased storage is not worth the inconvenience.

What is the threshold? Maybe around 5:1, or compression to 20% of the original size.  Include many input data which compress that much or more in a compression benchmark.

Incidentally, most lossy compression of media hits that ratio or better.

Another category of useful compression might be compression that is fast enough to be transparent.  This will depend on the bandwidth of other parts of a pipeline that transfers and uses data.

Monday, February 20, 2017

[uyyrhizz] IDE type annotations

Ideas for a desirable feature of a Haskell IDE:

Good: IDE pops up the type signature of the library function or symbol under the point.  Emacs haskell-mode can do this.

Better: IDE is aware of static scoping, let binding, and imports to really know what function you are referring to.  However, if you forgot to import, it still tries to be helpful, guessing at a library function and offering its signature as well as a reminder that you need to import it.

Better: If the function does not have an explicit type signature, the IDE does type inference to figure it out.

Better: if the type is polymorphic, the IDE also provides the type of the function as instantiated where it is used, instead of just the polymorphic type where it was declared.

Wednesday, February 15, 2017

[jjlddkmc] Pick your own house lock

Instead of leaving a concealed key outside the house for when one accidentally locks oneself out, leave lockpicks concealed outside the house.  This is less disastrous if someone bad discovers it.

Leaving the lockpicks at your house avoids needing to carry them on your person, possibly avoiding legal issues in jurisdictions where possession is considered proof of intent.

Of course, learn to pick your own house lock first.  This is aided by American tradition of having terribly insecure door locks in many places.

[lqdaenrs] Fun games of no strategy

Create a game which has no strategy (though it might present the illusion of requiring strategy) but which is still enjoyable to play.  One way is each time playing results in novel occurrences, perhaps through where simple rules can interact in interesting, beautiful, and complicated ways.  A randomizer can ensure new regions of the state space get explored each time.

[dptxehvj] Face CAPTCHA

Humans can presumably read faces, gauging emotion, better than computers.  This could be the basis for a CAPTCHA similar in style to reCAPTCHA: a bunch of pictures of faces that people form consensus on what emotion it is conveying.

[uxnvpywt] Free speech as a scapegoat

Enumerate historical examples in which free speech was blamed for a problem, speech was curtailed, and the problem persisted, thereby proving that speech was incorrectly blamed.

[jzvhfndr] Tor for C2

Brian Krebs reports that the command and control server for botnet was hosted by an ISP in Ukraine, and complaining up the ISP tree eventually knocked it offline.  However, such a server seems to be the perfect use case for a Tor hidden service.  Why was it not done?

Monday, February 13, 2017

[crhnyxty] Competent smuggler

In an alternate universe, Luke and Ben hire a different smuggler to transport themselves to Alderaan.  Perhaps someone more competent, less flying by the seat of his pants, who demonstrates a spectacular array of clever tricks to "avoid Imperial entanglements".  (Most of the time, Han, Chewbacca, and the Millennium Falcon rely only on speed and gunfire.)

[rnsmkgjj] Matter disappearing

Astronomy has a few nice examples of large quantities of matter turning into energy.

Of course, stellar nuclear fusion.

A supernova converts a large amount of the progenitor star into neutrinos.  While technically not massless, because neutrinos interact so little with anything, it seems like mass just disappeared.

In a black hole merger, a significant amount of mass gets radiated away as gravitational waves.

[lkajhfjz] Great glass elevator

It seems relatively easy to simulate in virtual reality the visual experience of traveling straight up and down.  There are many ways to do it, from projecting a fully real environment (previously, tower) to traveling in a completely synthesized world.

Consider altering the stereo depth, the distance between the eyes, at different heights.

Why do you want to be an astronaut?

[megjnlno] Copyright causes history not to be recorded

Artists have incentive not to record what influenced or inspired their artistic works because of fear of copyright lawsuits from those they cite.  But such documentation would be useful for historians.

This documentation might be significant beyond just curiosities of history: it might show how society is knitted together, which would be powerfully useful.

Inspired by Marvin Gaye Estate versus Blurred Lines.

[omgbdhjk] Panning and rotating rectangle

Tile a rectangular image, then place a rectangular viewport the same size as the image on the plane.  No matter the offset or orientation, exactly the entire image will be visible, though cut up.  (Is this fact interesting or obvious?)  Slide and turn the viewport around to offer different views of the same image.  Easiest is irrational slope and constant irrational rate of rotation, so the viewport will never repeat.

[fprrzelf] Copyright education at classical music concerts

Distribute educational material at performances regarding what copyright duration was when the performed work was created.

"XYZ was incentivized to compose the work you will hear tonight by copyright protection -- exclusive right to royalties -- of 0 years.  Compare this to copyright term for works composed nowadays: 95 years.  Is music better nowadays?"

Wednesday, February 08, 2017

[cmrfqpcl] Before and outside the Big Bang

The universe is and has always been infinite in size.  It has also existed forever in time.  We'll explain these assumptions later (tl;dr: Occam's Razor).  We are challenging the conventional notion that the universe had a start point in time, the Big Bang, and at that start point it was infinitesimally small.

A long time ago, the infinite universe was very hot and dense, so hot that the 4 known fundamental forces (gravity, strong, weak, EM) were merged into one.

Space expanded, so the universe got cooler.  Note that space remained infinite in size as it expanded, kind of like multiplying infinity by 2.  It's twice as large, but still infinity.  Things close together got further apart throughout the infinite universe as it expanded.

At some time point, Tgravity, it got cool enough for gravity to separate out from that one merged fundamental force.  Tgravity is a negative number for reasons we'll explain later.

Space expanded more, the universe got cooler, and at time point Tstrong, the strong nuclear force separated from the electroweak force.  Actually, we'll define Tstrong to be 0 for reasons we'll explain later.  So, immediately after this time 0, the forces were gravity, strong, and electroweak.

Space expanded (a lot) more, the universe got cooler, and the weak nuclear force separated from the electromagnetic force at time T_weak.  We actually know the value of T_weak to be about 10^-12 seconds based on particle accelerator experiments which can recreate the temperature of the universe (slightly) before T_weak.

We wrote above that space expanded "a lot" because, during some interval between 0 and T_weak, inflation happened.  It happened much closer to the 0 end.  More about that later.

The unconventional selection of Tstrong=0 is motivated by philosophical and practical considerations of what we can and cannot know.  There is a huge energy gap (10^12) between the electroweak and Grand Unified Theory scales: GUT explains the universe between Tgravity and 0, i.e., "negative time".  We will "never" be able to do experiments at the GUT scale: certainly not on Earth.  They are too unimaginably difficult: a trillion times more energy than the LHC.  Therefore we will never be able to know (that is, experimentally confirm) what the universe was like at or before time 0.  Incidentally, this means we will never know what time Tgravity was.

Similarly, we will never, ever, be able to experimentally confirm a Theory Of Everything (TOE) a.k.a quantum gravity a.k.a. string theory, a theory about what the universe was like before the negative time point Tgravity, called the Planck scale.  In fact, time points before Tgravity might be ill-defined, because gravity separating out from the other forces means that only then did spacetime come to exist, so only then did time itself and consequently things like causality come to exist.  Before that point, timey-wimey wibbly wobbly.

(Maybe our descendants or alien civilizations will prove me wrong about what we can scientifically know, then we will regret this choice of zero (like Fahrenheit).  Scientific American's The Amateur Scientist did whimsically propose building an Ultimate Collider to test TOEs.)

Actually time might have also behaved funny during inflation: inflation did very strange things to space, so we speculate it also did strange things to spacetime and consequently time.  We may never understand inflation: it is so close to the GUT scale that experiments probing it seem almost as unimaginable as experiments testing a GUT.  It might have been better to define the end of inflation as the zero time point.  Only then did time start flowing the way we experience it now.  The quoted value of T_weak above is the time interval between the end of inflation and the end of the electroweak epoch.

Nevertheless, even though we will never know what the universe was like before time 0, we will assume that it always existed all the way out to negative infinity.  (We may need some yet undefined notion of what it means to exist before time itself began to exist at Tgravity.)  We assume infinite existence because it is the simplest model: Occam's Razor.  If we don't assume it, then we have to explain more complicated things: what existed before the universe burst into being?  Why did the universe burst into being?

Similarly, we assume that space is infinite. Currently, there is a finite patch of the universe we can see, because light has had time to reach our eyes.  Astronomers call this the Observable Universe, which is kind of a confusing name.  Better would have been Our Finite Patch Of The Universe.  Lots of confusion stems from conflating "universe" (assumed infinite) and "observable universe" (definitely not infinite).  Even though we cannot see beyond Our Finite Patch Of The Universe, we assume that the universe extends infinitely beyond it.  This is again the simplest model.  Otherwise we have to explain complicated things like, what does the edge of the universe look like?  What exists beyond the edge?

Similarly, we also assume that space has always been infinite.  At no point in time was the entire universe compressed into a point.  Things were denser and closer back then, but the extent of space was always infinite.  This is the simplest model: otherwise, we have to explain complicated things like, what existed outside of the finite (in fact zero-volume) point?  How did the universe transition instantaneously from 0 to infinite in size?

When cosmologists say, at such and such point in time, the universe was the size of a grain of sand, it is actually confusing shorthand for, the chunk of space that eventually expanded to Our Finite Patch Of The Universe was, back then, the size of a grain of sand.  It is just shorthand for the expansion factor between then and now.  That sand-grain-sized chunk of space back then was still part of an infinite universe.

The conventional narrative that the universe started from an infinitesimal point at the Big Bang is derived from running the equations of General Relativity backward in time.  If you do that, it does predict a singularity, and conventionally, that singular point is defined as the zero point in time, as opposed to a later point in time Tstrong defined as zero above.  However, running GR backwards all the way to the singularity is a little bit silly, because other things happen on the way to the singularity, namely some GUT, some TOE, which might interfere with the prediction of the singularity.  Or, in this essay, we assume they definitely will interfere and prevent the singularity because otherwise it leaves us with the complicated questions mentioned above that we are avoiding by Occam's Razor.

Throw a ball, and we can plot a parabola, then extrapolate where the ball will land.  This is analogous to extrapolating that the universe began as a singularity.  However, we are actually throwing a ball toward a wall of fog.  This fog corresponds to the GUT scale, time 0, that we will never have knowledge beyond.  We have no idea what lies in the fog; we have no idea whether the ball will land at the extrapolation of the parabola into the fog.  This essay assumes that something analogous to a bottomless pit exists inside the fog: the ball never lands; the universe has no beginning.

I suppose the more accurate analogy is we see a ball having exited from a foggy area traveling a parabolic path.  From where and how was the ball launched?

In critique of this essay: because we will never be able to test a GUT or TOE, the only way to choose among them seems to be by Occam's Razor again.  Are there simple such theories which permit the GR singularity or something analogous?  There probably are.

[fsnyoxuk] Data horcruxes

1. Start with some data.
2. Cryptographically sign the data.
3. Expand it with an error correcting code.
4. Break it up into pieces, perhaps individual bytes.
5. Choose a nonce, which will be common to all the pieces.
6. Add the nonce to each piece.
7. Add a sequence number to each piece.
8. Cryptographically sign each piece.
9. Expand each piece with another error correcting code.
10. Scatter the pieces.

The data will be difficult to destroy: the data can be reconstructed from a partial collection of partially damaged pieces and verified as authentic.

Kind of a solution in search of a problem.  Previously.  The signature and nonce make the minimum size of a piece annoyingly large.

The total number of pieces needs to be encoded somewhere.  The public key to verify the signatures needs to be stored elsewhere.  Other problems?

[ejwpwgww] Earth as panspermia origin

Large meteorites have hit the earth, creating a splash, launching chunks of earth into space.  Many of those chunks probably had living microorganisms which hitched a ride to whichever next planet that launched chunk of earth then smashed into.

Inspired by Martian meteorites that landed on Earth.

In this way, Earth has probably seeded a large, perhaps cone-shaped, region of the galaxy (or beyond) with life over that past 3 billion years.  Maybe like a contagious constantly traveling constantly sneezing patient zero.  How large is that region?

If there is a habitable planet within that region, what is the probability it escaped infection by Earth?  On one hand, space is big.  On the other hand, there has been a lot of time.  There could also be indirect infections where a planet seeded by Earth thrived, got hit by another meteorite, then chunks of it and its life get launched into space (propagated outbreak in epidemiology).

Of course, one wonders whether Earth itself got seeded from elsewhere.

[bixwyjax] ZPAQ busy beaver

The ZPAQ compressed file format specifies a virtual machine.  This suggests a contest of designing small files which will uncompress (decompress) into large but finite output.

Also, uncompress into interesting output.

[vlvnvito] Monoculture trees

Many famous examples of a disease killing a lot of plants are in agriculture (potato famine) where monoculture likely played a large role in the disease being able successfully infect many plants.

Exceptions seem to include chestnut blight and Dutch elm disease.  Were those trees somehow monocultural also?  What other monoculture trees are there where a disease might quickly kill most of them someday?

[ajwillzv] Pen is mightier than the sword

Substitute the string (without spaces) mightierthanthesword for the word penis in contexts where the latter might be censored.

Ironically, the original aphorism justifies censorship.

[bqbrezti] Is the particle physics desert empty?

The particle physics desert theory states that all fundamental particles have mass less than 1 TeV or greater than 10^13 TeV.  There is a desert between 1 and 10^13.

Can this theory be tested without having to test all the way up to 10^13 TeV?  If one has to do that, the theory is useless.  In particular, can the theory be proven correct (a weird thing to do to a theory) by only testing up to 1 TeV?

What is the nature of inflation, neutrino mass, dark matter, and dark energy?  Assuming the desert theory is proven true, will the answers to these questions definitely be found before 1 TeV?  Or, if the answers aren't found, will we definitely know we will not be able know the answers until we can build (at least) GUT-scale particle accelerators?

Of course, astronomers can observe relics from when the universe was at GUT-scale energy to try to answer these questions.

[ariplvdv] GUT and TOE beauty contest

Grand Unified Theories and Theories Of Everything are difficult to test and disprove.  They cannot be tested on current or even reasonably imaginable future particle accelerators.  We can check that a theory agrees with observations in the low-energy regime, and whether they match astronomical observations of faint relics from the universe's high-energy era.

Given these difficulties, selecting a good such theory becomes more of a question of aesthetics than science.  Which such theories are beautiful and which are ugly?  What defines beauty of a theory?  Occam's Razor is likely important.  Given a precise definition of beauty, find, perhaps computationally, the optimally beautiful theory which agrees with weak and faint observations.

The E8 Theory Of Everything likely attracted attention due to its aesthetics.

Tuesday, February 07, 2017

[euzzsqsw] Inflation inside a black hole

Inside a black hole, density and consequently temperature become very high.  At some point of collapse, well inside the event horizon, does the density and temperature resemble the early universe?  Hypothesize inflatons then get produced, causing inflation, a repulsive force which counterbalances gravity and prevents the core from collapsing to a singularity.  This is analogous to the various other processes that counterbalance gravity in normal stars, white dwarves, and neutron stars.

Previously (1) (2) (3)

Inflation seems like an extremely powerful phenomenon based on what it did to the universe.  How much mass would a black hole need to have to overpower inflation?

Philosophically, do we even care what is going on inside an event horizon?

I suppose it matters for black holes with no event horizon, naked singularities, which, if the above hypothesis is correct, won't be singularities, just extremely dense chunks of matter surrounded by very weird spacetime.

[xxmnulmq] Chestnut brain

The inside of chestnuts look strikingly like brains.  What evolutionary fitness function were each tying to optimize that they both converged on the same shape?  Why do chestnuts look the way they do compared to other nuts?  (Possibly centuries of cultivation.)

[cqluwcao] The lighter particle was harder to make

It is curious that the Higgs boson, mass 125 GeV, was finally first seen at the LHC which has 8 TeV (maybe 7) collision energy, whereas the top quark with greater mass 172 GeV was seen earlier at the Tevatron with its only 1.96 TeV collision energy.

Electron-positron colliders tend to be more efficient in terms of converting collision energy into particle mass, but as best as I can tell, neither particle was seen at the LEP which had collision energy 209 GeV.  This might be explained by energy being converted into mass must be produced as matter-antimatter pairs (more generically, some collection that will decay and annihilate back to no mass), so even a perfectly efficient LEP will max out at particle mass 104.5 GeV.

Monday, February 06, 2017

[kxwixtrh] Density of Carmichael numbers

Estimate the number of Carmichael numbers less than x as

c(x)=x*exp(-k*log(x)*log(log(log(x)))/log(log(x)))

Formula (by Erdos, 1956) is from the Wikipedia page.  There is an unknown constant k, which will be discussed later.

The probability that a number is a Carmichael number is p=c(x)/x.  For the generation of a PGP RSA key, we need 4 primes: 2 primes for the master key, 2 primes for the subkey.  The probability that any of the 4 are Carmichael numbers is approximately 4*p (truncating the binomial expansion).  Primes are half the size of the modulus, so the probability of generating a bad key (at least one Carmichael number) is

pr(n)=4*c(2^(n/2))/(2^(n/2))

We explore various values of that unknown constant k.  It turns out the result is quite sensitive to k.  Empirical calculations on the Wikipedia page up to 10^21 (approximately 2^69) suggest k is around 1.86.

If we estimate k=1.8, then we get the following results.  The probability of failure on (absurdly small) 512-bit keys: 3.56e-44 ; 2048-bit keys = 3.63e-159 ; 4096-bit = 3.54e-303 .

If we far more conservatively estimate k=1.0, then 512-bit = 1.35e-24 ; 2048-bit = 1.76e-88 ; 4096-bit = 1.73e-168 .

The probabilities are probably acceptably small to not worry about accidentally encountering a Carmichael number, though you never know about that constant k.  So Fermat tests are fine, no need for the additional complexity of Miller-Rabin.

Friday, February 03, 2017

[zihjrysc] Alpha and Omega

It starts out a children's story, but ends apocalyptic.  Inspired by Harry Potter.  But no one author is skilled at all the styles, so it may be better written collaboratively.

Or, it ends as survival horror.

[vnqzswbf] Ender Purim

Ender spares the life of just one enemy Formic instead of genociding them all.

Saul spares the life of just one enemy Amalekite (Agag) instead of genociding them all as God Commanded.  Haman, a descendant of that survivor, goes on to wage genocidal warfare against the Jews.

Tell a continuation of the Ender saga in which the Formics, descendants of the egg Ender spared, return many generations later and wage genocidal warfare against the humans.  Perhaps with some science fiction time travel (Star Trek: First Contact), that second war is the one Mazer Rackham wins.  Celebrate yearly the anniversary of Rackham's miraculous victory.

Thursday, February 02, 2017

[plwpicim] Direct versus indirect encryption

Direct: Ciphertext encrypted with a key.  Key derived from a password.

Indirect: Ciphertext encrypted with a key X.  Key X is encrypted with a key Y.  Key Y is derived from a password.

There are probably more official names for these.

Indirect encryption allows changing the password without having to reencrypt everything, so seems attractive for things like disk encryption or filesystem encryption.  However, it seems more vulnerable to attack.  If the attackers can get a hold of encrypted X, then they can do a password guessing attack against it, which if successful could be useful even after the user changes their password (changing Y).  What other attacks?  What defenses are there?

Wednesday, February 01, 2017

[dsfjlwim] Transmitting compressed files

A certain absurdity is possible when transferring a file over scp between two filesystems that support transparent compression, e.g., btrfs: File is stored compressed with zlib (other options possible; this is the most absurd).  Uncompressed by a kernel module to make it visible to userspace program.  scp compresses the file with zlib for transmission over the wire.  Receiving scp unconpresses the file, then writes it to the filesystem.  Kernel recompresses the file with zlib to write to the compressed filesystem.

[fmsethjs] High precision UT1

The Earth's rotation is not stable, causing the need for leap seconds.  How precisely is its instability known from moment to moment?

The way to measure it is probably to look at stars with a telescope, noting the time and telescope orientation, though the details of how to do it seem tricky.  Maybe quasars and radio telescopes.

Inversely, how do astronomers keep their telescopes stably pointed at the same location in the sky for long exposure photographs if the earth to which their telescopes are anchored rotates unstably beneath them?

Sit down, then stand up.  Your movement altered the Earth's rotational moment of inertia and consequently its rate of rotation, which in principle could be detected, then maybe the measurement deconvolved to recover your movement.  Anything that involves movement of mass, for example air molecules vibrating in speech, affects the Earth's rotation.  We can imagine a sophisticated surveillance system that monitors actions on Earth by seemingly absurdly observing distant quasars to extremely high precision.

Less ridiculously, the unstable rotation of the Earth could be a source of entropy for a random number generator.  There used to be a random number generator powered by a Lava Lamp.  The Earth is the ultimate Lava Lamp: variations in rotation are caused by movement of magma within the mantle or core.  How many bits per second of entropy can the Earth's rotation produce?

[lrrrishw] Union

The word union could be pronounced onion as if it had the prefix un-.  Onion, then, could be pronounced differently, too.