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"F**k my Hat, I didn't know that!" Amazing things you've only just found out

Started by daf, December 14, 2017, 08:40:45 PM

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Sebastian Cobb

Isn't sha a hashing algorithm (i.e. one-way) rather than an encryption algorithm?

MojoJojo

Yes, possibly it's referring to preimage attacks, where you calculate plaintext to generate a specific hash.

Paul Calf

Yes, that's right. At the moment it's vastly unlikely that anyone could do that. This video explains it really clearly:

https://www.youtube.com/watch?v=S9JGmA5_unY

Sebastian Cobb

I hope I'm alive when quantum computing is able to smash open encryption schemes. It'll be like that encrochat thing but on a geopolitical level.

kittens

Quote from: Paul Calf on April 29, 2021, 08:54:25 AM
There is no mathematical proof that it's impossible to find a method to trivially reverse SHA256. If someone did find a way to do it, almost all current encryption would be useless.

652AHS

NoSleep


Paul Calf


pigamus

When you press the button to cross the road, the little twirly thing underneath for blind people.

Fr.Bigley

Quote from: pigamus on April 29, 2021, 02:33:36 PM
When you press the button to cross the road, the little twirly thing underneath for blind people.

I go around removing these so I see a lot of sightless strewn across our road. Quite funny really but the missus thinks I'm immature.

touchingcloth

Quote from: pigamus on April 29, 2021, 02:33:36 PM
When you press the button to cross the road, the little twirly thing underneath for blind people.

I think those only appear on crossings where there isn't a beeping sound which plays when the traffic lights are red, or where the pedestrian crossing lights are on the near rather than far side.

Slightly related to the "mates who bullshit" and the "untrue things people say about you" threads of late, when I was in secondary school people used to say that manually twizzling that little twirly thing would make the lights change quicker.

On a similar note, I've heard that some traffic lights, in particular temporary ones around roadworks, react to the flashing of emergency vehicle lights by changing to green and so you can fool them by flashing your headlights at them. Sometimes when I've been stuck for an age at temporary lights late at night with literally no traffic coming from the other direction I've flashed and the lights have changed, so this one may be for reals.

Sonny_Jim

Quote from: touchingcloth on April 30, 2021, 01:27:29 AM
Sometimes when I've been stuck for an age at temporary lights late at night with literally no traffic coming from the other direction I've flashed and the lights have changed, so this one may be for reals.
It's more likely the light uses a IR/light sensor that gets covered in road grime so flashing your lights gives it the boost it needs to 'see' your car properly, but I'm completely pulling that out of my ass and I'm sure someone who knows will chime up.

Endicott

Quote from: steve98 on April 29, 2021, 10:24:30 AM
We should take measures against the quantum cryptographers, before it's too late. Terminal measures.

You want them to be forced to use VT100s?


olliebean

Quote from: touchingcloth on April 30, 2021, 01:27:29 AM
I think those only appear on crossings where there isn't a beeping sound which plays when the traffic lights are red, or where the pedestrian crossing lights are on the near rather than far side.

No, there's one near me which has lights on the far side, beeping, and rotating cones. I assumed they were intended for people who are both blind and deaf.

They used to be rotating cylinders. I don't know when/why they changed to cones.

MojoJojo

Hmmm, my personal theory was that the cones were on lights which were close to residential homes, as a beep would be annoying for residents.

pigamus


beanheadmcginty

I always smear shit on the little cones. Not to be horrible to blind people, but as a tasty treat for their guide dogs.

JesusAndYourBush

Quote from: touchingcloth on April 30, 2021, 01:27:29 AM
On a similar note, I've heard that some traffic lights, in particular temporary ones around roadworks, react to the flashing of emergency vehicle lights by changing to green and so you can fool them by flashing your headlights at them. Sometimes when I've been stuck for an age at temporary lights late at night with literally no traffic coming from the other direction I've flashed and the lights have changed, so this one may be for reals.

I've also heard that reversing a little way and driving forwards again will trigger a sensor and make them change quicker.  Obviously only do this when you're on your own, not when there are other cars behind you!

canadagoose

"Roblox" is supposed to be like "Roadblocks", isn't it? Just got that.

touchingcloth

Not really FMH, but Peri Gilpin's wiki page says:

Name: Peri Gilpin
Born: Peri Kay Oldham
Parents: Jim O'Brien
Spouse: Christian Vincent


Icehaven

Bomber jackets are so called because they were worn by WW2 pilots on bombing missions, and for each mission they completed they'd paint a bomb on it.

Gulftastic

Quote from: icehaven on May 03, 2021, 05:01:16 PM
Bomber jackets are so called because they were worn by WW2 pilots on bombing missions, and for each mission they completed they'd paint a bomb on it.

What do cats paint on them?




Sonny_Jim

Some scientists also fed an elephant an insane amount of LSD and it unsurprisingly died.  They were trying to simulate some form of mating behaviour and they completely fucked up:

https://www.illinoisscience.org/2016/06/lsd-and-the-elephant/

Make me proper sad thinking about it, less Jacobs Ladder and more chemical Saw.


Fr.Bigley

Interesting considering  you can't OD on acid. That elephant obviously had a prior smack problem or summat.


Fr.Bigley

That would be the pun based lateral explanation  most certainly.

buzby

Quote from: touchingcloth on April 30, 2021, 01:27:29 AM
I think those only appear on crossings where there isn't a beeping sound which plays when the traffic lights are red, or where the pedestrian crossing lights are on the near rather than far side.
Time to mine my 'Greatest Hits' for a relevant post:
Quote from: buzby on September 30, 2017, 10:42:21 AM
The spinning cone at the base of the Push Button Unit (PBU) is as mentioned above a tactile indicator for the visually impaired. It tends to be fitted in areas where the traditional bleeper is considered a noise nuisance, or there are a lot of crossings in the same site and audible signals would overlap.
Quote
On a similar note, I've heard that some traffic lights, in particular temporary ones around roadworks, react to the flashing of emergency vehicle lights by changing to green and so you can fool them by flashing your headlights at them. Sometimes when I've been stuck for an age at temporary lights late at night with literally no traffic coming from the other direction I've flashed and the lights have changed, so this one may be for reals.
It's a myth. Most temporary traffic light systems use Microwave Vehicle Detectors (MVDs), not optical ones. They sometimes have a photocell fitted to reduce thier brightness at night (this is is common with standard traffic lights systems). They are supplied to DoT specifications and have 4 modes of operation:
All Red – holds signals on red to all approaches.
Manual (MAN) – should be used to stop traffic if the shuttle lane has to be occupied for short periods (e.g. for unloading).
Fixed Time (FT) – may be used while awaiting the arrival of the engineer if the equipment needs attention. On some controllers there is no fixed time mode.
Vehicle Actuation (VA) - if there are no approaching vehicles, the signals will revert to red in both directions. The first vehicle to arrive will register a demand for the signals to change on that approach.  Following vehicles will extend the time that the green light is shown  (settable on the controller). The signals will change either when the last vehicle has passed, or after the maximum time the green signal has been set for. If a detector has not registered a demand for 2.5 minutes, the detector generates it's own demand via its 'nudge circuit'. This will mean that at quiet times the signals will change at least every two and a half minutes.

Some other countries (notably the US) do use optical-based Traffic Signal Pre-Eption systems for emergency services vehicles (they use a system  called Opticom that has an infra red strobe on the vehicle and a detector on the traffic light) and some use audio detectors to detect the siren (detecting the rapid 'tweet'  siren they switch to when approaching junctions).