block

In cryptography, a block cipher is a deterministic algorithm operating on fixed-length groups of bits, called blocks. They are specified elementary components in the design of many cryptographic protocols and are widely used to the encryption of large amounts of data, including data exchange protocols. It uses blocks as an unvarying transformation.
Even a secure block cipher is suitable for the encryption of only a single block of data at a time, using a fixed key. A multitude of modes of operation have been designed to allow their repeated use in a secure way to achieve the security goals of confidentiality and authenticity. However, block ciphers may also feature as building blocks in other cryptographic protocols, such as universal hash functions and pseudorandom number generators.

View More On Wikipedia.org
Recent contents Top users
  1. B

    Installing a new radiator

    How's it going? I'm more of a maintenance guy, so I'd like to pick the brains of the installers if I can. In my house I have a decommissioned bbu/fire (no gas supply going to it anymore). The room it's in doesn't have a radiator as the BBU/fire used to be adequate. So, I'm looking to rip the...
  2. R

    Connect toilet to existing stack in block of flats?

    We live in a modern-ish block of flats. We want to remodel our flat (no structural changes), which the Lease allows but we need a Licence to Alter. We want to site an en suite bathroom where our kitchen currently is and have a smaller kitchen. The existing soil stack is cast iron and appears to...
  3. R

    Blanking cap to block off overflow on kitchen sink?

    hoping someone can help. Trying to fit a washing machine under a sink and the only thing that's stopping it is overflow into the waste - would like to just remove and cap off. Is there something out there I can use as can't seem to find anything so far. I've attached a photo thanks in advance
  4. B

    Is there a way of finding out if you have a block forming in the toilet pipe?

    Basically we have a toilet which most of the time is fine and flushes everything no problem and leaves no traces. But maybe once a week someone would, do their business and a while later it would appear back in the bottom of the bowl. The toilet paper wouldn't though. It is strange, how come...
  5. Sid Viscous

    RF Room Stat wiring

    Electrics not my strong point, got a Siemens rf room stat to wire into this: Looks decidedly home made! Where the bloomin' heck do I start? Reciever req's permenant L & N ( the easy bit! ) LX=common, L1=switched live. All ideas welcome
  6. M

    Is there such a thing as a cold block in heating systems?

    hi there Where i work we have a six inch district heating main which feeds building via a vavle system controlled by iq3 trend controllers the question is can a closed or partially opening valve say at 60 to 70 percent cause a cold block to occur due to the restricted flow around the building...
  7. M

    Keston C55 Control Block Unit

    Hi all, Has anyone come across anything like this before?? I serviced a Keston C55 last week for a regular client. On removal of the case I saw that the control block unit (PCB) had fallen from its mountings onto the fan (The plastic had become brittle & with the same consistency of dry...
  8. D

    Fixings in thermalite block

    I'm about to mount a basin without a pedestal on a thermalite block wall any one got any top tips with regards to fastenings. The plugs it comes with which the studing fits look as though they will just crush the thermalite block when they are tightened.
  9. J

    Globe taps: I don't understand how to disassemble it

    Hi everyone! It always starts like this : "My tap is dripping, so I want to replace the join" Then comes the catch: "I can't disassemble the tap". Have a look at picture below, showing you my globe tap : Except for the cylinder at the very top (which is the tap itself), it seems like it's...
  10. K

    New Girl on the block!!!

    Hi Everyone, My names Kareen, I may look and sound like some sort of malibu barbie but I'm a gas engineer and plumber all the way, self employed and working in North London looking forward to getting to know you all :) P.s. (what's a trackback?)
  11. H

    munting double rad on to plastic wall panelling advice please

    Have a 600 x 1000 double radiator to mount in my bathroom, will be mounting it on to a solid block wall, that has been clad with plasterboard, and pvc marble effect wall panelling... bearing in mind the weight of the radiator empty no water.... would i better mounting the brackets to the...
    • handsomejackuk
    • Thread
    • advice block brackets double plasterboard plastic please wall
    • Replies: 6
    • Forum: Plumbing Jobs | The Job-board
  12. F

    Big mess of pipes on block & beam floor

    Hi All, just joined,& my knowledge is very very sparse, so any advice is welcome. Ground floor of extension is a block & beam floor. Our plumber doing the first fix persuaded us to go with plastic hep2o & he has done a crappy job leaving us with pipes clipped to the concrete floor which we need...
  13. W

    Block of flats

    I live in a block of 27 flats, built 1960s, owners with share of freehold, we appoint a Management Company to deal with utilities etc. Several flats - including mine - have been experiencing interrupted supply and water then bursting from taps when turned on. We raised this with a Management...
  14. L

    Heating but no hot water

    Good evening all and welcome to my question time! I have a honeywell programer on a job and it is calling for heating and hot water. But it is only doing the heating side. If i move the 2 port over manually it works but if i let got it shuts off. I have put an electrical testing pen on the wire...
    • lewisplumber
    • Thread
    • block change heating hot hot water motor no hot water valve water
    • Replies: 16
    • Forum: Plumbing Jobs | The Job-board
  15. M

    cold block in pipe work

    hi all i have a large accomodation builing which is heated by a 2 inch pipe all the way around rooms and uses aluminum fins in the rooms to dispate the heat. the problem is i have two ground floor corridoors cold and hot at each end of the repspective corridoor and only have a radiator type...
  16. P

    'Active' range basin mono block taps

    I have ten new ideal standard basin mono block taps if anyone is interested They are the 'Active' range,without pop up waste attachment Around £ 85 to purchase,will accept £ 42 each Left over from contract last year,wrong order never re collected
  17. P

    Soil and surface water

    On a Victorian block of flats the roofer is recommending connecting gutters into soil stacks and removing the downpipes. The block is 3 storeys high with a basement and approx 40m. The drainage is all on the rear elevation of the block and at the moment there are 6 soul stacks and 6 downpipes...
  18. M

    Air block on hot tap problem

    Hello all, i have just replaced my toilet and basin/taps in my bathroom upstairs, I have run the system and all other hot feed taps are fine in the house but I cant get a drop out the one ive changed, ive checked all valves and had the mixer tap off and apart. One thing to mention is I...
  19. N

    new kid on the block

    HI, I am a registered gas engineer with long term plumbing and building maintenance background. I have trained many an apprentice, and am keen to pass on advice and experiences as well as to chew the cud/ swing the lamp a little. I am an advocate of best practice, and loathe seeing shoddy...
  20. R

    block valiant heat exchanger

    Hi, My ecotech bolier valiant is less than 5 years old and has been powerflushed, has a magnaclean and Y taps but gets blocked approx every 6 weeks, i'm getting really fedup with this, any help from anybody, i'm getting desperate........

Newest Plumbing Threads

Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock