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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.

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  1. P

    Anyone here had block paving done recently lol...

  2. T

    Centre feed rad, H block and what the hell is a T insert!

    Having had a week of asking various help desks i'm hoping that somebody on here will be able to add some clarity to the following situation? Having purchased a Quinn centre feed radiator and fitting straight TRV and Lockshield the rad didn't heat up evenly and sometimes not at all. Quinn tell...
  3. M

    commissioning boilers in a block of flats

    I have got a mate who is working for a plumbing company in a block of flats. Apparently there is 20 wb boilers installed that need to be commissioned. All gas carcass is track pipe and is all on show, and the boiler is the only appliance. All flues exit out of the wall. Would you commission...
  4. T

    block inlet in inspection chamber?

    hi Does anyone the correct way (i.e. that building control will accept?) of blocking off a disused inlet inside a plastic inspection chamber. I have removed the downstairs loo from my house and wish to cap of the inlet inside the chamber. I know that you can buy caps that can be fitted on to...
  5. H

    Parquet

    Have a job to pipe up new rad and below the carpet and above the floorboards looks to be Parquet flooring. How do you remove/refit this neatly?
  6. S

    Can you Cut Back Old Lead Soil Pipe inside Block of Flats?

    Hi, We are having a new Back to wall toilet fitted with a 'box' built to hide the cistern. The plumber/bathroom fitter has said he cannot cut into the old lead soil pipe which will be behind the pan. if we could cut it back though it would mean this 'box' could be reduced which would be...
  7. C

    Shared SVP in Block of Flats

    In blocks of flats, is it normal for all the toilets to share a single soil stack / SVP? So if there is a blockage in the lower part of the SVP, what is to stop the sewage backing up and overflowing from a lower flat's toilet? All the sewage from the flats above would keep flowing down and the...
  8. S

    Expansion vessel size large system

    Have seen many differing formulas for this. My system volume is 1417 litres My static head is 11 metres PRV set at three bar One calculation I found said it should be 145 litres... can you imagine? Another said 50, which seems more realistic! Cheers
  9. plumb_know

    fixings for breeze block

    hi everyone, I need to hang a heavy vertical rad (10,500 btu) onto a dot and dab plasterboard wall with breeze block behind it. This is the first time i have needed to hang something this heavy onto breeze block and am just looking for some advice on what fixings are best for this situation...
  10. M

    monoblock bath tap in corner off bath

    Hi I have a customer that wants a mono block bath tap in the corner of a bath. The area were they want it has no wood under it I plan on drilling the hole and putting a piece of plywood under it siliconed to the underneath of the bath and then when I fix the tap it will hold it in place. Anyone...
  11. P

    Do Combined Feeds And Vents Also Suffer Blockages?

    Just a general question. It seems to be well known that for certain reasons, cold feeds on o/v systems collect magnetic debris. Do combined F and Vs get the same problem?
  12. P

    Partial block in toilet.

    Over the last few weeks the upstairs en suite toilet hasn't been flushing completely. Occasionally there were remains in the bowl after flushing, but there was no significant rise in the water level in the bowl on flushing. I have started with the basics like dumping an extra bowlful of water...
  13. hammers4spanner

    block

    Anyone else getting this grey bar which says vb block across top of your screen when you go to access likes?? my likes have gone :((
  14. P

    first ever Block and Quayle

    just found this pic on a page i belong to on facebook thought some of you would like to see it it's the first ever B&Q, and it was in southampton.
  15. B

    flkexicom hydro block

    has anyone done the plastic hydro block on the glowworm flexicom the last one I passed to group service as it looked a pain - got one that's weeping had a quick look but the 2 retaining screws seem unaccessible from underneath due to the boiler jig base - should I do or pass on
  16. U

    Low water pressure by day, strong pressure by night

    Hi, have found this forum especially for this annoying issue. About 3 months ago the water pressure in the shower dropped for seemingly no reason. During the day, from 7am - 7pmish, hot water taps throughout the flat are poor, worst in the shower. The cold taps are better but not as good as...
    • Uberalles1982
    • Thread
    • block during flats low water pressure night pressure strong water water pressure
    • Replies: 12
    • Forum: Plumbing Jobs | The Job-board
  17. R

    New Kid on the block saying hello

    Hi Everyone I'm Rob, I have just started out on my own after qualifying in Plumbing & Domestic Heating NVQ Level 2. It's going OK at the moment but it's quite nerve-racking being self-employed and trying to make a living out of bathroom installations. Hope to be able to ask questions of you...
  18. M

    Fastening a small basin to breeze block

    Hi, I was wondering what is the best way to fasten a small basin to a wall consisting of plasterboard and then a fairly soft breeze block ? Any thoughts appreciated
  19. S

    Replacing synchronous motor.

    Hi All Sorry to bother you, but I am replacing the synchronous motor on a Honeywell motorized valve. I've bought the universal synchronous motor that Tool Station sell. One of the two wires from the original goes to a connecting type block on the valve. There are three other wires going into...
  20. M

    installing a coooker that is over 5 years old in a tower block question

    evenin lads......quick question for ya as I'm not sure on the answer....can a free standing cooker that is made before 2008 and has no fsd's be installed in a tower block? I know someone who is moving into a flat and has an older cooker......just because she is moving into a flat does she have...
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