Functions, Hash Functions, Cryptography - Discussion

Blockchain and Bitcoin 101
#306

  1. A fuction takes an input, manipulates it and gives us an output.

  2. Calculate the output of the following

f(x) =
x^2 if x is even
x+10 if x is odd

What will be the outputs for the following inputs?

a. f(2) = 4
b. f(7) = 17
c. f(0) = 0

  1. f(x) = ((x)/4)-5

a. f(30) = ((30)/4)-5
f(30) = (7.5)-5
f(30) = 2.5

1 Like
#307
  1. Secured Hash Algorithm SHA256
    2.Each single target modification cannot change the value of the target by more than 4x its previous value.
#308

I don’t know what you mean by that, doesn’t have anything to do with hash functions imo. The reason why its hard to brute force is because of the sheer number of possible outputs.

Also you posted your homework in the discussion thread, pleas post it in the corresponding thread for the homework next time. :slight_smile:

#309

Thank you I am new at using this forum. Guess I will find the homework section. It was the link that was send in the homework

#310

You have the link to the topic in the academy lecture in homework. Should take you directly where you need :slight_smile:

#311

Thank you all for your contributions to the discussion board. In my opinion, this was a very interesting discussion. In my opinion, the learning materials provided were very informational. Within the references I learned the basics of cryptocurrenies. For example, keys and addresses.

  • Basics
  • Private Key
  • Pubic Key
  • Address
  • Digital Signature
  • Code and examples
    I learned that Bitcoin is decentralized. The public key can be described as equivalent to an account number. The private key can be described as being equivalent o a password; of which is a 256 bit number and/ or two to the power of 256.
    Furthermore, the learning materials within this discussion explained elliptic curve secp256k1. Therein, trapdoor functions were discussed. The random point on the elliptic curve multiplied by the key plus the message; of which is a special number calculated by generating three points on the elliptic curve. Signature works is the terminology for these elliptical curve mathematics and/ or elliptic curve cryptography. One can generate their own private and/ or public keys.
    Keys and addresses with extra security utilize SHA256, RIPEMD160, and HASH160 (Public Key). Typically hexadecimal storage is utilized.
    The terminology known as checksum utilizes alpha-numeric 16 and 62 characters. Although, “I’s, 1’s, zeros and O’s” are excluded. Hence; Base58 and Base58check.
    The references also discussed OpenSSL, /dev/urandon (Linux), Programming Liberary, and Secure Random (Ruby).
  • N= number of points on a curve.
  • secp256k1 = find parameter of N
  • Even = 002
  • Odd= 03
    Private and Public keys =32 bites
    Version byte can be computed with binary private and public keys; utilizing SHA256, RIPEMD160.
    A code sample of Ruby key generator programming was informative and interesting.
    According to scholarly research; a bitcoin address can be described as a 160-bit hash of a ECDSA keypair, public portion of the public/private, (en.bitcoin.it).
    I learned that normal addresses currently begin with 1. Addresses of which are from script hashes use 3. Whereas testnet addresses typically begin with m or n.
    Merkel trees were also a topic of this discussion. Accordingly, Merkel trees are considered to be tamper free and are utilized to contain and/ or hash transactions in a block. Such as the merkle root and the merkle tree
    In conclusion, I learned many technical terminologies and enjoyed the knowledge gleaned from others.
    Best Regards,
    Craft

References:

https://youtu.be/GT6AuURD8Y0
File:Hash_Tree.svg bitcoinwiki.org
Technical background of version 1 Bitcoin addresses - Bitcoin Wiki bitcoin.it
https://youtu.be/VkWiTvPnTcY
https://discord.gg/5fmxWWM

Royal Fork Blog, (n.d.), NEO4J… Retrieved From: https://rubykeygenerator.rb

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#312

I was doing great until “function”. I just do not understand it. How is it used on the blockchain? I do not understand the symbols and the math involved. Nothing makes sense. Is there any beginner tutorial into “function”? This is so frustrating. I want to learn this but I am lost. Thank you…really appreciate it…will even toss in a free cat toy if you can help me. …lol. Thank you

1 Like
#313

Its basically used everywhere from key generation to block calculation. We did our best to describe functions in the course. Is there anything particular you don’t understand I can help you with? :slight_smile:

#314

All is well, need to move on.

#315

Can someone help explain how someone can confirm my digital signature if that signature is based on my private key? Seems like no one should be able to see my public signature or public key and be able to confirm the private key that was used to create it, right?

#316

Hi everyone, I have a quick question. A private key will generate a public key but it’s a one way direction so would that be a Hash function?

#317

No the digital signature hashes the message with the private key which can then be verified using the public key. Its a process that utilizes the Elliptic curve function, which you can learn more about it in the beginning of our privacy course. It has a good explanation how the function works from the mathematical stand point. Beware its not for the faint of heart. :smile:

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#318

Its not SHA256 that is used to derive public keys but another function called the Elliptic curve, its quite a bit more complex than hash function therefore its not mentioned in the beginners course. :slight_smile:

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#319

Thank you for that cheers :slightly_smiling_face:

#320

Wonder what hash functions are in cryptography?

#321

You mean which ones exist? There is a lot of them, don’t know them by hand tbh :stuck_out_tongue:

#322

What just happened in lesson 4? I need to study functions, any good resources?

#323

Hash Functions are the glue that makes bitcoin (and other cryptocurrencies) work.

Don’t EVER lose your private key, it is more valuable than gold, and make sure you TRIPLE check any addresses that you send to. all transactions are final.

1 Like
#324

So, what are the problems with crypto, specifically Ethereum and Bitcoin? At this writing the fees assigned to ETH transactions are out the roof. It costs far too much to get out what one puts in on the ETH blockchain, yes? Second, BTC blockchain seems like idiot shit now and what is with all these whales investing into BTC if it moves at a snails pace and developers don’t want to change a thing and keep it as some store of value? I am seeing less and less value just from the basics to this course. Maybe I should learn programming or something, eh?

#325

yeah, something like that, there are many algorithms to remember