Hashing: Why & How?

Why do we wish to reduce a long list to a short one? How to do it, so that the short list will identify the long list. How to do it so that it is impossible to identify the long list from the short one, and the implications of the fact that many long lists share the very same short list. Hashing configurations: straight encryption, MD4, MD5, SHA-1, SHA-2.

[@walterbril630]

I am by no means (very) technical, but this is the first time I see such a clear explanation. So thank you so much!

[@GideonTheTeacher]

+Walter Bril Thank you Walter: Explaining technical stuff to non experts in the field is very important on many levels, and is missing everywhere. I am glad I can help in that regard.

[@khaledpac7797]

u are the best professor.....i like ur method to explain the problems....thank you very much professor

[@bestforgebuilder]

I dont know what it is about your presentations but these help me understand so well. I especially appreciate how you build the foundation first and work from there. Great lecture

[@GideonTheTeacher]

Thank you bestforgebuilder, I am really glad that you absorb it all so well!

[@fsl001]

I am not a technician or engineer, however, I found the explanation very fascinating. I may have to go back a few steps though. Thank you :-)

[@GideonTheTeacher]

+Dj Mr Cool -- you are most welcome. I try to build my explanation on common sense not on uncommon knowledge.

[@sladkacokoladka]

Subscribed after the first 2 minutes because of the clarity of explanation I found in this video (and later in the rest of your videos). Thank you professor! I found awesome study material on your website too.

[@GideonTheTeacher]

+sladkacokoladka Thank you much (although I cannot decipher your name). Keeps me motivated!

[@a.a7907]

I liked the way you explained the points from least important to most important. I also enjoyed my time here. Definitely, I will look for more videos in this channel.

[@anjalirai7127]

I was going through hashing concepts, and this was a clear and crisp good explanation. Thank you

[@GideonTheTeacher]

thanks for your kind words

[@behlulshaljani864]

You simplified hashing into a sentence...thank you for this clear explanation...

[@thecuriousone12]

First video I've seen of yours and I subscribed within the first minutes. Very clear explanation, thank you!

[@GideonTheTeacher]

Thanks Beata, it feels good to be useful!

[@abdullahafridi7947]

I was searching for hash and somehow ended up here.

[@salaheamean]

I like the way u initiated your presentation.It is an experience. Thank you sir

[@GideonTheTeacher]

+salahe amean -- thank you! Glad it was useful for you!

[@AlrightIamdone]

awesome sir searched across google..found uh the best ....

[@mouradbarakat123]

Thanks for the video. I have one comment about what you said on information theory, that a short list cannot contain all the information about the long list, just because it's shorter, that is not correct. For example, a compression algorithm can reduce the size of a big list into a smaller one without any loss of information, then a decompression algorithm can reproduce the original list again.

[@gkuhgjgh]

Very nice Prof Gideon. Its very nice tutorial.

[@JohnSmith-he5xg]

Great point that collisions are unavoidable (and can only be made more difficult to find) given that we are taking an input of size S and trying to represent it in a smaller size L.

[@javierlainez8376]

excellent explanation...almost give up trying to find out how it work on a simple way.

[@eliotsalinas7504]

Thank you for the simplicity.

[@educationmadeeasy6420]

Wonderful explanation shalom to you

[@GideonTheTeacher]

+Education Made Easy -- thank you, and Shalom!

[@kalyanhr]

Awesome explanation Sir.

[@MrBahaaeldinmohamed]

very detailed explanation I hope if I can get more videos related to the cryptography topics Thanks too much

[@krantikumar2709]

Thank you sir for your beautiful explanation. Super.

[@naresh1234nmnn]

very very good explanation . I salute you sir ji.

[@GideonTheTeacher]

+nareshk kumar Thank you! My pleasure!

[@pragadheshwarankulandhaive6466]

nice explanation sir!,,,u did well in this video,,and thanks

[@mediel6378]

Loved your explanation

[@mosesa180675]

Hi Gideon Samid, it's really good and clear explanation .. i can say it's very basic flow .. fantastic job ... i am looking how HASH JOINS functionally and its behaviour work.. i gone through Google but no luck ... Looking your assistance. Regards Moses

[@MUHAMMADUMARASHRAFBCS]

Excellent Explaination.......

[@hattube]

Question: does " implications of the fact that many long lists share the very same short list" mean that there are already collisions we don't even know about?

[@QuantumDataInc]

This guy is great.

[@AliOpridai]

Finally I get it! Thank you!

[@burhanhassan4377]

Hi,nice explanation. Can you please name encryption protocols having cipher size greater then plain text size. 😊

[@eldadmo]

You are great! Toda raba!

[@GideonTheTeacher]

Shalom ubracha-

[@shaniranshul]

Nice, short & effective

[@STPADDYSHUGOSPLAY]

great explanation! thanks!

[@terryburke7605]

Thank you. Very informative

[@fireeye33]

I love this video thank you so much!!

[@taospencer1403]

Are Salts stored on the local machine? As there not stored in the database??

[@roseb2105]

sorry Just clarifying the point of cypher is to condense the text so that if we have limited spots available we have less chance of multiple data parts sharing the same spot and therefore avoiding collision? Also I like the way this lecture is presented would you mind making a video on how the polynomial has function works?

[@GideonTheTeacher]

+Rose B Thank you Rose, if I find time, will upload the requested video.

[@tucom3556]

i need to see some lectures abut minhash and minhash types please

[@DioXin]

Thank you prof. ! Toda Raba! :-)

[@GiveItNowX]

Thank you Sir!

[@jacobkurien]

you sir are a legend

[@GideonTheTeacher]

Thank you Jacobkurien. I am not a legend, but I think the world will be a better place if we learn to explain better. Clarity prevents mistakes and misuse.

[@doctorlazarus8854]

Gideon Samid You, sir, are very humble! :)

[@GiangPham-mg3vd]

thank you sir! thanks a lots!

[@bmurph24]

Much appreciated.

[@kfudub7254]

Thanks for the video. One question: A hash (like SHA-256) could be used to copyright? Like a song? If the SHA256 of the file (mp3) + date, this could be used in a certificate?

[@GideonTheTeacher]

+Kfu Dub yes, it could, but you need a trusted party to carry out the hash.

[@danielalt7508]

13:55 Why do we use blocks instead of every character its own block or have one long string hashed itself many times?

[@jasonlowmiller9869]

Efficiency

[@DevendraSingh-uz2wk]

Thanks a lot!! 👏👏👏👏 #Gideonsamid sir

[@qassemaleid9774]

thank you

[@saumya8149]

Awesome

[@RedShipsofSpainAgain]

5:40 You're talking about the pigeonhole principle here, correct?

[@pr1493]

he ain't using pigeonhole principle here.. he's just applying the hash function to get a fixed size hash value of s bits, say for l bit block of data.

[@abdullgoes]

thank u

[@GideonTheTeacher]

Glad that you like it!

[@abdulblessinger6659]

lol - catch a few hi lights

[@ecapanema]

bitcoin is not based on sha-2 but on sha-256

[@parallel041]

😄😄😄

[@zachdems4634]

How can we get a cryptocurrency backed by anything

[@GideonTheTeacher]

check out bitmint.com, or the book "Tethered Money: Managing Digital Currency Transactions" available on Amazon (Elsevier 2015), including digital edition.

[@Makerbreaker10]

This sir looks like Walter white😂

[@adon2424]

Lost me at l to the e. Poor delivery.

[@walkingbobblehead]

2 advanced 4 me salami 2 u

[@tejara01]

wtf is with the clicking...