Hash functions are mathematical functions and cryptography is basically the science of it. It has nothing to do with smart contracts and dapps. Cryptocurrencies heavily rely on these concepts. 
2 Likes
Quote from Cryptimi reading:
“In essence, a hash algorithm is a universal translator for computers. It is able to receive any form and size of data, including digits, letters or even larger media files, and translates them into an alphanumeric string of a certain size. This size can vary depending on the hash function in use. Standard and popular sizes include the 64-bit, 128-bit and the 256-bit.”
I do have a question to better understand the subject. @Alko89, may you help please?
- Does it mean that we convert video file into alphanumeric string of a certain size and send over to counterparty using blockchain? And then they can watch? How the addressee see it later on? Still as an video file? Is it converted or encrypted then?
1 Like
Everything in a computer is a stream of numbers, but that doesn’t mean its hashed or encrypted. Video or audio is encoded in a binary format for transmission over a digital medium.
You can also hash it, that would give you some kind of id for easier access maybe, depends on the use case.
3 Likes
Two great videos, less than 4 and 8 minutes respectively. Good quick overviews that allow deeper searches into concepts than need refreshing, such as modulus math from second video.
How asymmetric (public key) encryption works
https://www.youtube.com/watch?v=E5FEqGYLL0o
Public key cryptography - Diffie-Hellman Key Exchange (full version)
3 Likes
Great! 
But I think these videos would fit more in the Public key cryptography topic than here.
OOOOOH!!! That’s why there are 32 bit and 64 bit operating systems! I always wondered but never cared enough to figure that out.
The system architecture doesn’t have much to do with bits in a hash number 
Sure they are both just “bits” in a fundamental view. But the 32 and 64 bit PC architectures mostly refer to memory addresses (also other things); how many memory address locations a PC can access.
1 Like
haha thank you! Now am actually enlightened. Much appreciated.
Hi @ivan what exactly is the process to verify that a signature came from a certain private key by only using the public key? Thank you!
You utilize the elliptic curve function. It usually has a formula like (k + j)H = kH + jH , where:
kH = PubKey
k = PrivKey (this is the number of transformations on the curve)
j = shared secret
kH + jH is publicly know
By using this function you can prove you know k by providing the solution to k + j without revealing k.
If you want to learn more you can check our privacy course that explains this in more detail.
Thank you very much!
So i have a Question: How come indexing is not a viable way to break the SHA256? Logically it would take a lot of work and time but in theory it should be a viable method? I hope someone can help, thanks a lot!
It would take an enormous amount of storage to index all SHA256 outputs and it would also take a few lifetimes to do it because the number of possible outputs is so large.
No computer today can calculate all possible outputs in a reasonable amount of time.
1 Like
Thanks for your answer! Is that why some people are scared of quantum computers because they will be able to solve the SHA256?
1 Like
Some say they could for now there hasn’t been any that could break SHA256. There are also quantum resistant algos that are being developed and if the hash function gets broken eventually the network can hard fork to a new algo to remain secure.
2 Likes
Thats pretty cool. Thanks a lot!
Hash functions is the topic that I became more interested because I find it mind blowing and its such a beauty the way data is mixed in a way that it will always produce a unique Hash. And like every decision in life… its Irreversible.
4 Likes
I loved this course very interesting and helpful, I hope the quantic computers never get to destroy the beauty of Bitcoin.
1 Like
Thanks Ivan for explaining how smart contracts and dApps work. It’s fascinating to understand how blockchain technology will change improve the infrastructure of the internet.
2 Likes
You got it!