awesome-awesomeness/terminal/blockchains

Mining Digital Gold one Block at a Time?! • Don't Expect to Get Insanely Rich (Quick) • Tulips :tulip::tulip::tulip: (like Blockchains) are Great and Gorgeous (and will Endure)

b0 = Block.first(                                                                         
        { from: "Dutchgrown", to: "Vincent", what: "Tulip Bloemendaal Sunset", qty: 10 }, 
        { from: "Keukenhof",  to: "Anne",    what: "Tulip Semper Augustus",    qty: 7  } )
                                                                                          
b1 = Block.next( b0,                                                                      
        { from: "Flowers",    to: "Ruben",   what: "Tulip Admiral van Eijck",  qty: 5  }, 
        { from: "Vicent",     to: "Anne",    what: "Tulip Bloemendaal Sunset", qty: 3  }, 
        { from: "Anne",       to: "Julia",   what: "Tulip Semper Augustus",    qty: 1  }, 
        { from: "Julia",      to: "Luuk",    what: "Tulip Semper Augustus",    qty: 1  } )
...                                                                                       

(Source: blockchain_with_transactions.rb (blockchain.rb/blockchain_with_transactions.rb))


                                                                                                                 Awesome Blockchains

A collection about awesome blockchains - open distributed databases w/ crypto hashes incl. git ;-).  Blockchains are the new tulips :tulip::tulip::tulip:.

Contents:

- Frequently Asked Questions (F.A.Q.s) & Answers (#frequently-asked-questions-faqs--answers)
- Do-It-Yourself (DIY) - Build Your Own Blockchain (#do-it-yourself-diy---build-your-own-blockchain)
  - Python (#python) • Ruby (#ruby) • JavaScript (#javascript) • Java (#java) • Go (#go)
- Blockchain Articles (#blockchain-articles)
- Blockchain Books (#blockchain-books)
- Blockchain (Lite) Crypto Hash Libraries (#blockchain-lite-crypto-hash-libraries)
- Git, Git, Git - The Stupid Content Tracker with Crypto Hashes (#git-git-git---the-stupid-content-tracker-with-crypto-hashes)
- Classic Tulip Mania (#classic-tulip-mania)
- Awesome Awesomeness (#awesome-awesomeness)



What's News?

For blockchain books, see the new Best of Crypto Books page » (https://openblockchains.github.io/crypto-books/)

The Open Blockchains Book of the Year 2020 Award Goes To...

! (i/libra-shrugged.png)
Libra Shrugged: How Facebook Tried to Take Over the Money (https://davidgerard.co.uk/blockchain/libra/)
by David Gerard, November 2020, 182 Pages --
_Introduction: Taking over the money  ++
A user's guide to Libra   ++
The genesis of Libra: Beller's blockchain ++
To launch a Libra: Let’s start a crypto  ++
Bitcoin: why Libra is like this  ++
The Libra White Papers  ++
Banking the unbanked  ++
The Libra Reserve plan and economic stability ++
Libra, privacy and your digital identity  ++
The regulators recoil in horror  ++
David Marcus before the US House and Senate ++
July to September 2019: Libra runs the gauntlet  ++
October 2019: Libra's bad month  ++
Mark Zuckerberg before the US House  ++
November 2019: The comedown  ++
Central bank digital currencies  ++
Epilogue: Libra 2.0: not dead yet  ++
Appendix: 2010–2013: The rise and fall of Facebook Credits_

For more about Diem (formerly Libra), see the Awesome Diem (formerly Libra) and Move page » (https://github.com/openblockchains/awesome-diem)

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

For crypto quotes, see the new 100+ Best of Crypto Quotes - I HODL, you HODL, we HODL! - BREAKING: BITCOIN JUST BROKE $22 000! page » (https://github.com/openblockchains/crypto-quotes)

The Best Crypto Quote "Oracle Saying" of the Year 2020 Award Goes To...

▐ SEC Investor Education:
▐ - Don't understand an investment?
▐ - Don't invest in it.

Yes, but what if there's only 21 million of it?

  \- Trolly McTrollface



Frequently Asked Questions (F.A.Q.s) & Answers


Q: What's a Blockchain?

A: A blockchain is a distributed database with a list (that is, chain) of records (that is, blocks) linked and secured by
digital fingerprints (that is, cryptho hashes).
Example from blockchain.rb (blockchain.rb/blockchain.rb):

**#<Block:0x1eed2a0                                                                    
  @timestamp     = 1637-09-15 20:52:38,                                                
  @data          = "Genesis",                                                          
  @previous_hash = "0000000000000000000000000000000000000000000000000000000000000000", 
  @hash          = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b">,
 #<Block:0x1eec9a0                                                                     
  @timestamp     = 1637-09-15 21:02:38,                                                
  @data          = "Transaction Data...",                                              
  @previous_hash = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b", 
  @hash          = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743">,
 #<Block:0x1eec838                                                                     
  @timestamp     = 1637-09-15 21:12:38,                                                
  @data          = "Transaction Data......",                                           
  @previous_hash = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743", 
  @hash          = "be50017ee4bbcb33844b3dc2b7c4e476d46569b5df5762d14ceba9355f0a85f4">,
  ...                                                                                  

! (i/blockchain-jesus.png)


Q: What's a Hash? What's a (One-Way) Crypto(graphic) Hash Digest Checksum?

A: A hash e.g. eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743
is a small digest checksum calculated
with a one-way crypto(graphic) hash digest checksum function
e.g. SHA256 (Secure Hash Algorithm 256 Bits)
from the data. Example from blockchain.rb (blockchain.rb/blockchain.rb):

def calc_hash                                                                                  
  sha = Digest::SHA256.new                                                                     
  sha.update( @timestamp.to_s + @previous_hash + @data )                                       
  sha.hexdigest   ## returns "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743"
end                                                                                            

A blockchain uses

- the block timestamp (e.g. 1637-09-15 20:52:38) and
- the hash from the previous block (e.g. edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b) and finally
- the block data (e.g. Transaction Data...)

to calculate the new hash digest checksum, that is, the hash
e.g. be50017ee4bbcb33844b3dc2b7c4e476d46569b5df5762d14ceba9355f0a85f4.


Q: What's a Merkle Tree?

A: A Merkle tree is a hash tree named after Ralph Merkle who patented the concept in 1979
(the patent expired in 2002). A hash tree is a generalization of hash lists or hash chains where every leaf node (in the tree) is labelled with a data block and every non-leaf node (in the tree)
is labelled with the crypto(graphic) hash of the labels of its child nodes. For more see the Merkle tree (https://en.wikipedia.org/wiki/Merkle_tree) Wikipedia Article.

Note: By adding crypto(graphic) hash functions you can "merkelize" any data structure.


Q: What's a Merkelized DAG (Directed Acyclic Graph)?

A: It's a blockchain secured by crypto(graphic) hashes that uses a directed acyclic graph data structure (instead of linear "classic" linked list).

Note: Git uses merkelized dag (directed acyclic graph)s for its blockchains.


Q: Is the Git Repo a Blockchain?

A: Yes, every branch in the git repo is a blockchain.
The "classic" Satoshi-blockchain is like a git repo with a single master branch (only).



Do-It-Yourself (DIY) - Build Your Own Blockchain

! (i/fake-dilbert-blockchain.png)


Python (#python) •
Ruby (#ruby) •
JavaScript (#javascript) •
Java (#java) •
Go (#go)


Python

Let's Build the Tiniest Blockchain in Python Series by Gerald Nash

- Let's Build the Tiniest Blockchain In Less Than 50 Lines of Python (Part 1) (https://medium.com/crypto-currently/lets-build-the-tiniest-blockchain-e70965a248b), July 2016
- Let's Make the Tiniest Blockchain Bigger With More Lines of Python (Part 2) (https://medium.com/crypto-currently/lets-make-the-tiniest-blockchain-bigger-ac360a328f4d), July 2016



Build Your Own Blockchain: A Python Tutorial (http://ecomunsing.com/build-your-own-blockchain)
by Eric Munsing, March 2017, (Source) (https://github.com/emunsing/tutorials/blob/master/BuildYourOwnBlockchain.ipynb)


Learn Blockchains by Building One (in Python) (https://hackernoon.com/learn-blockchains-by-building-one-117428612f46)
by Daniel van Flymen, September 2017, (Source) (https://github.com/dvf/blockchain) -- The fastest way to learn how Blockchains work is to build one


Build Your Own Blockchain (in Python 3) Series by Jack Schultz, (Source) (https://github.com/jackschultz/jbc)

- Part 1: Creating, Storing, Syncing, Displaying, Mining, and Proving Work (https://bigishdata.com/2017/10/17/write-your-own-blockchain-part-1-creating-storing-syncing-displaying-mining-and-proving-work/), October 2017
- Part 2: Syncing Chains From Different Nodes (https://bigishdata.com/2017/10/27/build-your-own-blockchain-part-2-syncing-chains-from-different-nodes/), October 2017
- Part 3: Writing Nodes that Mine and Talk (https://bigishdata.com/2017/11/02/build-your-own-blockchain-part-3-writing-nodes-that-mine/), November 2017



A Practical Introduction to Blockchain with Python (http://adilmoujahid.com/posts/2018/03/intro-blockchain-bitcoin-python/)
by Adil Moujahid, March 2018, (Source) (https://github.com/adilmoujahid/blockchain-python-tutorial)


Ruby

How Does Bitcoin Force Consensus Among Byzantine Generals? (http://www.akitaonrails.com/2017/11/01/how-does-bitcoin-force-consensus-among-byzantine-generals) by Fabio Akita, November 2017

blockchain-lite - Build your own blockchains with crypto hashes; revolutionize the world with blockchains, blockchains, blockchains one block at a time!
 (https://planetruby.github.io/calendar/advent2017/01-blockchain-lite) by Gerald Bauer, Ruby Advent Calendar 2017 / Day 1, December 2017

merkletree library - Build Your Own Crypto Hash Trees; Grow Your Own Money on Trees (https://planetruby.github.io/calendar/advent2017/19-merkletree.html) by Gerald Bauer, Ruby Advent Calendar 2017 / Day 19, December 2017

centralbank command line tool (and library) - Print Your Own Money / Cryptocurrency; Run Your Own Federated Central Bank Nodes on the Blockchain Peer-to-Peer over HTTP
 (https://planetruby.github.io/calendar/advent2017/24-centralbank.html) by Gerald Bauer, Ruby Advent Calendar 2017 / Day 24, December 2017

A guide to building a blockchain & cryptocurrency from scratch (https://antoinefink.com/building-a-blockchain-and-cryptocurrency-in-ruby) (Source) (https://github.com/antoinefink/melon) by Antoine Fink, April 2021


Crystal

Write your own blockchain and Proof-of-Work (PoW) algorithm using Crystal (https://medium.com/@bradford_hamilton/write-your-own-blockchain-and-pow-algorithm-using-crystal-d53d5d9d0c52) by Bradford Lamson-Scribner, May 2018,
(Source) (https://github.com/bradford-hamilton/crystal-blockchain)


JavaScript

Writing a Tiny Blockchain in JavaScript (https://www.savjee.be/2017/07/Writing-tiny-blockchain-in-JavaScript/)
by Xavier Decuyper, July 2017

Node.js Blockchain Imlementation: BrewChain: Chain+WebSockets+HTTP Server (http://www.darrenbeck.co.uk/blockchain/nodejs/nodejscrypto/) by Darren Beck, November 2017, (Source) (https://github.com/dbbddb/BrewChain) -- Protecting the tea making 
ledger from unscrupulous colleagues

Build your own Blockchain in Javascript/Visualization of Blockchains (https://github.com/nambrot/blockchain-in-js) by Nam Chu Hoai,  January 2018


TypeScript

Naivecoin: a tutorial for building a cryptocurrency (https://lhartikk.github.io) by Lauri Hartikka, (Source) (https://github.com/lhartikk/naivecoin)


Java

Creating Your First Blockchain with Java, Part 1 (https://medium.com/programmers-blockchain/create-simple-blockchain-java-tutorial-from-scratch-6eeed3cb03fa) by Kass, December 2017, (Source) 
(https://github.com/CryptoKass/NoobChain-Tutorial-Part-1)

Kotlin

Let's implement a cryptocurrency in Kotlin (https://medium.com/@vasilyf/lets-implement-a-cryptocurrency-in-kotlin-part-1-blockchain-8704069f8580) by Vasily Fomin, July 2018,
(Source) (https://github.com/VasilyFomin/kCoin)


SQL

Blockchain by Example in SQL Server (https://medium.com/@benjaminsky/blockchain-by-example-in-sql-server-8376b410128) by Benjamin Campbell, December 2017, (Source) (https://github.com/benjaminsky/BlockchainMessenger)


Rust

Building Blockchain in Rust Series by Jacob Lindahl, GeekLaunch, (Source) (https://github.com/GeekLaunch/blockchain-rust), (Slide Decks in PDF) (https://github.com/GeekLaunch/slides)
- Part 1: Blocks and Hashing (https://medium.com/geeklaunch/blockchain-in-rust-01-blocks-hashing-4192f2265d3d), January 2019
- Part 2: Mining (https://medium.com/geeklaunch/blockchain-in-rust-02-mining-companion-guide-9106b7a7696d), January 2019
- Part 3: Chains and Checks (https://medium.com/geeklaunch/blockchain-in-rust-03-chains-checks-companion-guide-2714e1a76654), January 2019

Go

Building Blockchain in Go Series by Ivan Kuznetsov, (Source) (https://github.com/Jeiwan/blockchain_go)

- Part 1: Basic Prototype (https://jeiwan.cc/posts/building-blockchain-in-go-part-1/), August 2017
- Part 2: Proof-of-Work (https://jeiwan.cc/posts/building-blockchain-in-go-part-2/), August 2017
- Part 3: Persistence and CLI (https://jeiwan.cc/posts/building-blockchain-in-go-part-3/), August 2017
- Part 4: Transactions 1 (https://jeiwan.cc/posts/building-blockchain-in-go-part-4/), September 2017
- Part 5: Addresses (https://jeiwan.cc/posts/building-blockchain-in-go-part-5/), September 2017
- Part 6: Transactions 2 (https://jeiwan.cc/posts/building-blockchain-in-go-part-6/), September 2017
- Part 7: Network (https://jeiwan.cc/posts/building-blockchain-in-go-part-7/), October 2017



Blockchain Series in Go by by Coral Health (Source) (https://github.com/mycoralhealth/blockchain-tutorial)

- Code your own blockchain in less than 200 lines of Go! (https://medium.com/@mycoralhealth/code-your-own-blockchain-in-less-than-200-lines-of-go-e296282bcffc) by Coral Health, January 2018
- Part 2: Networking — Code your own blockchain in less than 200 lines of Go! (https://medium.com/@mycoralhealth/part-2-networking-code-your-own-blockchain-in-less-than-200-lines-of-go-17fe1dad46e1) by Coral Health, February 2018
- Code your own blockchain mining algorithm in Go! (https://medium.com/@mycoralhealth/code-your-own-blockchain-mining-algorithm-in-go-82c6a71aba1f) by Coral Health, March 2018


<!--
  it's more about bitcoin (and not about blockchain really)
C#

Programming The Blockchain in C# (https://programmingblockchain.gitbooks.io/programmingblockchain/)
-->


Talk Notes

- Blockchain! Blockchain! Blockchain! - Build Your Own Blockchains in JavaScript from Zero (Scratch) (https://github.com/geraldb/talks/blob/master/blockchain.md) by Gerald Bauer, Vienna.js, September 2017
- Blockchain! Blockchain! Blockchain! - Build Your Own Blockchains in Ruby from Zero (Scratch) (https://github.com/geraldb/talks/blob/master/blockchain_ruby.md) by Gerald Bauer, Vienna.rb, Dezember 2017
- Blockchain vs (Hyper) Ledger -- Inside (Hyper) Ledger Lite - Add Transactions One Block at a Time and Balance the Accounts (Books) (https://github.com/geraldb/talks/blob/master/hyperledger.md) by Gerald Bauer, Hyperledger Vienna, March 2018
- Blockchain! Blockchain! Blockchain! - Build Your Own Blockchains in Go from Zero (Scratch) (https://github.com/geraldb/talks/blob/master/blockchain_go.md) by Gerald Bauer, Vienna.go, April 2018


More

See Build your own Blockchain / Cryptocurrency (https://github.com/danistefanovic/build-your-own-x#build-your-own-blockchain--cryptocurrency) @ Build your own (insert technology here)




Samples

Blockchain from Scratch - Ruby Version

class Block                                                                              
                                                                                         
  attr_reader :timestamp                                                                 
  attr_reader :data                                                                      
  attr_reader :previous_hash                                                             
  attr_reader :hash                                                                      
                                                                                         
  def initialize(data, previous_hash)                                                    
    @timestamp     = Time.now                                                            
    @data          = data                                                                
    @previous_hash = previous_hash                                                       
    @hash          = calc_hash                                                           
  end                                                                                    
                                                                                         
  def self.first( data="Genesis" )    # create genesis (big bang! first) block           
    ## note: uses all zero for previous_hash ("0")                                       
    Block.new( data, "0000000000000000000000000000000000000000000000000000000000000000" )
  end                                                                                    
                                                                                         
  def self.next( previous, data="Transaction Data..." )                                  
    Block.new( data, previous.hash )                                                     
  end                                                                                    
                                                                                         
private                                                                                  
                                                                                         
  def calc_hash                                                                          
    sha = Digest::SHA256.new                                                             
    sha.update( @timestamp.to_s + @previous_hash + @data )                               
    sha.hexdigest                                                                        
  end                                                                                    
                                                                                         
end  # class Block                                                                       
                                                                                         
                                                                                         
#####                                                                                    
## let's get started                                                                     
##   build a blockchain a block at a time                                                
                                                                                         
b0 = Block.first( "Genesis" )                                                            
b1 = Block.next( b0, "Transaction Data..." )                                             
b2 = Block.next( b1, "Transaction Data......" )                                          
b3 = Block.next( b2, "More Transaction Data..." )                                        
                                                                                         
blockchain = **b0, b1, b2, b3**                                                          
                                                                                         
pp blockchain                                                                            
                                                                                         

(Source: blockchain.rb (blockchain.rb/blockchain.rb))

will pretty print (pp) something like:

**#<Block:0x1eed2a0                                                                      
  @timestamp     = 1637-09-15 20:52:38,                                                  
  @data          = "Genesis",                                                            
  @previous_hash = "0000000000000000000000000000000000000000000000000000000000000000",   
  @hash          = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b">,  
 #<Block:0x1eec9a0                                                                       
  @timestamp     = 1637-09-15 21:02:38,                                                  
  @data          = "Transaction Data...",                                                
  @previous_hash = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b",   
  @hash          = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743">,  
 #<Block:0x1eec838                                                                       
  @timestamp     = 1637-09-15 21:12:38,                                                  
  @data          = "Transaction Data......",                                             
  @previous_hash = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743",   
  @hash          = "be50017ee4bbcb33844b3dc2b7c4e476d46569b5df5762d14ceba9355f0a85f4">,  
 #<Block:0x1eec6d0                                                                       
  @timestamp     = 1637-09-15 21:22:38,                                                  
  @data          = "More Transaction Data...",                                           
  @previous_hash = "be50017ee4bbcb33844b3dc2b7c4e476d46569b5df5762d14ceba9355f0a85f4",   
  @hash          = "5ee2981606328abfe0c3b1171440f0df746c1e1f8b3b56c351727f7da7ae5d8d">** 


Comments from the reddit ruby posting (https://www.reddit.com/r/ruby/comments/70c30f/build_your_own_blockchain_in_20_lines_of_ruby/):

▐ Wait, so a blockchain is just a linked list?
▐ 
>> No. A linked list is only required to have a reference to the previous element, a block must
>> have an identifier depending on the previous block's identifier, meaning that you cannot
>> replace a block without recomputing every single block that comes after.
>> In this implementation that happens as the previous digest is input in the calc_hash method.



What about Proof of Work / Waste?

Let's add a proof of work / waste to the blockchain. In the classic blockchain you have to compute a block hash that starts with leading zeros (00). The more leading zeros the harder (more difficult) to compute. Let's keep it easy to compute with
two leading zeros (00), that is, 16^2 = 256 possibilites (^1,2). Three leading zeros (000) would be 16^3 = 4_096 possibilites and four zeros (0000) would be 16^4 = 65_536 and so on.

(^1): 16 possibilties because it's a hex or hexadecimal or base 16 number, that is, 0 1 2 3 4 6 7 8 9 a (10) b (11) c (12) d (13) e (14) f (15).

(^2): A random secure hash algorithm needs on average 256 tries (might be lets say 305 tries, for example, because it's NOT a perfect statistic distribution of possibilities).


Example:

def compute_hash_with_proof_of_work( difficulty="00" )                                         
  nonce = 0                                                                                    
  loop do                                                                                      
    hash = calc_hash_with_nonce( nonce )                                                       
    if hash.start_with?( difficulty )                                                          
      return **nonce,hash**      ## bingo! proof of work if hash starts with leading zeros (00)
    else                                                                                       
      nonce += 1              ## keep trying (and trying and trying)                           
    end                                                                                        
  end                                                                                          
end                                                                                            
                                                                                               
def calc_hash_with_nonce( nonce=0 )                                                            
  sha = Digest::SHA256.new                                                                     
  sha.update( nonce.to_s + @timestamp.to_s + @previous_hash + @data )                          
  sha.hexdigest                                                                                
end                                                                                            

(Source: blockchain_with_proof_of_work.rb (blockchain.rb/blockchain_with_proof_of_work.rb))

Let's rerun the sample with the proof of work machinery added.
Now the sample will pretty print (pp) something like:

**#<Block:0x1e204f0                                                                      
  @timestamp     = 1637-09-20 20:13:38,                                                  
  @data          = "Genesis",                                                            
  @previous_hash = "0000000000000000000000000000000000000000000000000000000000000000",   
  @nonce         = 242,                                                                  
  @hash          = "00b8e77e27378f9aa0afbcea3a2882bb62f6663771dee053364beb1887e18bcf">,  
 #<Block:0x1e56e20                                                                       
  @timestamp     = 1637-09-20 20:23:38,                                                  
  @data          = "Transaction Data...",                                                
  @previous_hash = "00b8e77e27378f9aa0afbcea3a2882bb62f6663771dee053364beb1887e18bcf",   
  @nonce         = 46,                                                                   
  @hash          = "00aae8d2e9387e13c71b33f8cd205d336ac250d2828011f5970062912985a9af">,  
 #<Block:0x1e2bd58                                                                       
  @timestamp     = 1637-09-20 20:33:38,                                                  
  @data          = "Transaction Data......",                                             
  @previous_hash = "00aae8d2e9387e13c71b33f8cd205d336ac250d2828011f5970062912985a9af",   
  @nonce         = 350,                                                                  
  @hash          = "00ea45e0f4683c3bec4364f349ee2b6816be0c9fd95cfd5ffcc6ed572c62f190">,  
 #<Block:0x1fa8338                                                                       
  @timestamp     = 1637-09-20 20:43:38,                                                  
  @data          = "More Transaction Data...",                                           
  @previous_hash = "00ea45e0f4683c3bec4364f349ee2b6816be0c9fd95cfd5ffcc6ed572c62f190",   
  @nonce         = 59,                                                                   
  @hash          = "00436f0fca677652963e904ce4c624606a255946b921132d5b1f70f7d86c4ab8">** 

See the difference? All hashes now start with leading zeros (00) and the nonce is the random "lucky number"
that makes it happen. That's the magic behind the proof of work.


Blockchain from Scratch - JavaScript Version

class Block {                                                                                   
                                                                                                
  constructor(data, previousHash) {                                                             
    this.timestamp    = new Date()                                                              
    this.data         = data                                                                    
    this.previousHash = previousHash                                                            
    this.hash         = this.calcHash()                                                         
  }                                                                                             
                                                                                                
  calcHash() {                                                                                  
    var sha = SHA256.create()                                                                   
    sha.update( this.timestamp.toString() + this.previousHash + this.data )                     
    return sha.hex()                                                                            
  }                                                                                             
                                                                                                
  static first( data="Genesis" ) {    // create genesis (big bang! first) block                 
    // uses all-zero previousHash                                                               
    return new Block( data, "0000000000000000000000000000000000000000000000000000000000000000" )
  }                                                                                             
                                                                                                
  static next( previous, data="Transaction Data..." ) {                                         
    return new Block( data, previous.hash )                                                     
  }                                                                                             
}                                                                                               
                                                                                                
                                                                                                
//////                                                                                          
// let's get started                                                                            
//   build a blockchain a block at a time                                                       
                                                                                                
b0 = Block.first( "Genesis" )                                                                   
b1 = Block.next( b0, "Transaction Data..." )                                                    
b2 = Block.next( b1, "Transaction Data......" )                                                 
b3 = Block.next( b2, "More Transaction Data..." )                                               
                                                                                                
                                                                                                
blockchain = **b0, b1, b2, b3**                                                                 
                                                                                                
console.log( blockchain )                                                                       

(Source: blockchain.js (blockchain.js/blockchain.js))

will log something like:

** Block {                                                                                  
     timestamp    : 1637-09-18 08:25:54,                                                    
     data         : 'Genesis',                                                              
     previousHash : '0000000000000000000000000000000000000000000000000000000000000000',     
     hash         : 'c396de4c03ddb5275661982adc75ce5fc5905d2a2457d1266c74436c1f3c50f1' },   
   Block {                                                                                  
     timestamp    : 1637-09-18 08:35:54,                                                    
     data         : 'Transaction Data...',                                                  
     previousHash : 'c396de4c03ddb5275661982adc75ce5fc5905d2a2457d1266c74436c1f3c50f1',     
     hash         : '493131e09c069645c82795c96e4715cea0f5558be514b5096d853a5b9899154a' },   
   Block {                                                                                  
     timestamp    : 1637-09-18 08:45:54,                                                    
     data         : 'Transaction Data......',                                               
     previousHash : '493131e09c069645c82795c96e4715cea0f5558be514b5096d853a5b9899154a',     
     hash         : '97aa3cb5052615d60ff8e6b41bef606562588c4874f011970ac2f218e2f0f4a8' },   
   Block {                                                                                  
     timestamp    : 1637-09-18 08:55:54,                                                    
     data         : 'More Transaction Data...',                                             
     previousHash : '97aa3cb5052615d60ff8e6b41bef606562588c4874f011970ac2f218e2f0f4a8',     
     hash         : 'e10e020f832e46c2b60e1c3c0412bd370b2fde5f0f782c16eb87d0313ea0d3a3' } ** 



Blockchain Articles

Reflections on the Blockchain (http://rufuspollock.com/2016/07/02/reflections-on-the-blockchain) by Rufus Pollock (Open Knowledge Foundation), July 2016 --
_The DAO: Code is not Law – and It’s Dangerous to Think So ++
The Internet changed the world - surely the Blockchain will too? ++
Gold-rush or Internet-rush? ++
Governance Matters in Bitcoin ++
The Myth of a Costless, Ownerless Network ++
Lessons from History_

On the Dangers of a Blockchain Monoculture (https://tonyarcieri.com/on-the-dangers-of-a-blockchain-monoculture) by Tony Arcieri, January 2016 --
_The Bitcoin blockchain: the world's worst database ++
Next-generation protocols ++
Decentralized ledger protocols ++
Bitcoin-NG ++
Blockchain! Blockchain! Blockchain! ++
The great decentralized database in the sky_


I Don’t Believe in Blockchain (https://www.tbray.org/ongoing/When/201x/2017/05/13/Not-Believing-in-Blockchain) by Tim Bray, May 2017


Minimum Viable Blockchain (https://www.igvita.com/2014/05/05/minimum-viable-block-chain/) by Ilya Grigorik, May 2014 --
_Securing transactions with triple-entry bookkeeping ++
Securing transactions with PKI ++
Balance = Σ(receipts) ++
Multi-party transfers & verification ++
Double-spending and distributed consensus -
 Requirements for a distributed consensus network;
 Protecting the network from Sybil attacks;
Proof-of-work as a participation requirement ++
Building the minimum viable blockchain -
 Adding "blocks" & transaction fee incentives;
 Racing to claim the transaction fees;
 Resolving chain conflicts;
 Blocks are never final ++
Properties of the (minimum viable) blockchain_

Blockchains by analogies and applications: How blockchain compares to Git, Raft, and other technologies. (https://www.oreilly.com/ideas/blockchains-by-analogies-and-applications)
by Kieren James-Lubin, January 2016 --
_Blockchains are databases ++
Understanding transactions ++
Persistent, replicated databases (related technology: Git) ++
Peer-to-peer networks (related technology: BitTorrent) ++
Distributed consensus (related technology: distributed databases, Raft) ++
Minting new coins (mining) ++
Embedded identities (related technology: TLS) ++
Smart contracts: Like SQL expressions & triggers ++
What can we really do with blockchains?_



Blockchain Books

Attack of the 50 Foot Blockchain: Bitcoin, Blockchain, Ethereum & Smart Contracts (https://davidgerard.co.uk/blockchain/table-of-contents/) by David Gerard, London, 2017 --
_What is a bitcoin? ++
The Bitcoin ideology ++
The incredible promises of Bitcoin! ++
Early Bitcoin: the rise to the first bubble ++
How Bitcoin mining centralised ++
Who is Satoshi Nakamoto? ++
Spending bitcoins in 2017 ++
Trading bitcoins in 2017: the second crypto bubble ++
Altcoins ++
Smart contracts, stupid humans ++
Business bafflegab, but on the Blockchain ++
Case study: Why you can’t put the music industry on a blockchain_


Mastering Bitcoin - Programming the Open Blockchain (https://github.com/bitcoinbook/bitcoinbook/blob/second_edition/ch09.asciidoc) 2nd Edition,
by Andreas M. Antonopoulos, 2017 - FREE (Online Source Version) --
_What Is Bitcoin? ++
How Bitcoin Works ++
Bitcoin Core: The Reference Implementation ++
Keys, Addresses ++
Wallets ++
Transactions ++
Advanced Transactions and Scripting ++
The Bitcoin Network ++
The Blockchain ++
Mining and Consensus ++
Bitcoin Security ++
Blockchain Applications_

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

! (i/trolly-ponzi.png)

BEWARE: Bitcoin is a gigantic ponzi scheme¹.
To the moon!? The new gold standard!?
Do NOT "invest" trying to get-rich-quick HODLing.
Why not? The bitcoin code is archaic and out-of-date.
Burn, baby, burn! Proof-of-work / waste is a global
energy environmental disaster
using 300 kW/h per bitcoin transaction (!) that's about 179 kilograms of CO₂ emissions².
Programmable money (or the internet of value)
for all future generations with (bitcoin) script
without loops and jumps (gotos) and all "stateless"!? LOL.

¹: (Source: Best of Bitcoin Maximalist - Scammers, Morons, Clowns, Shills & BagHODLers - Inside The New New Crypto Ponzi Economics (https://bitsblocks.github.io/bitcoin-maximalist))

²: Assuming let's say 0.596 kilograms of CO₂ per kW/h
(that's the energy efficiency in Germany) that's
about 179 kilograms of CO₂ per bitcoin transaction (300 kW/h × 0.596 kg). For more insights see the Bitcoin Energy Consumption Index (https://digiconomist.net/bitcoin-energy-consumption).

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――


Programming Bitcoin from Scratch (https://github.com/jimmysong/programmingbitcoin) by Jimmy Song, 2019 - FREE (Online Source Version) -- _Chapter 6 - Script (https://github.com/jimmysong/programmingbitcoin/blob/master/ch06.asciidoc) - How Script 
Works • Example Operations • Parsing the Script Fields • Combining the Script Fields • Standard Scripts • p2pk • Problems with p2pk • Solving the Problems with p2pkh • Scripts Can Be Arbitrarily Constructed • Conclusion ++_
_Chapter 8 - Pay-to-Script Hash (https://github.com/jimmysong/programmingbitcoin/blob/master/ch08.asciidoc) - Bare Multisig • Coding OP_CHECKMULTISIG • Problems with Bare Multisig • Pay-to-Script-Hash (p2sh) • Coding p2sh • Conclusion ++_
_Chapter 13 - Segregated Witness (https://github.com/jimmysong/programmingbitcoin/blob/master/ch13.asciidoc) - Pay-to-Witness-Pubkey-Hash (p2wpkh) • p2wpkh Transactions • p2sh-p2wpkh • Coding p2wpkh and p2sh-p2wpkh • Pay-to-Witness-Script-Hash 
(p2wsh) • p2sh-p2wsh • Coding p2wsh and p2sh-p2wsh • Other Improvements • Conclusion_


Programming Bitcoin Script Transaction (Crypto) Contracts Step-by-Step ( Beta / Rough Draft ) (https://github.com/openblockchains/programming-bitcoin-script)
by Gerald Bauer et al, 2019 - FREE (Online Version) --
_Let's start with building your own bitcoin stack machine from zero / scratch and let's run your own bitcoin ops (operations)..._


Programming Blockchains in Ruby from Scratch Step-by-Step Starting w/ Crypto Hashes... ( Beta / Rough Draft ) (https://github.com/yukimotopress/programming-blockchains-step-by-step)
by Gerald Bauer et al, 2018 - FREE (Online Version) --
_(Crypto) Hash ++
(Crypto) Block ++
(Crypto) Block with Proof-of-Work ++
Blockchain! Blockchain! Blockchain! ++
Blockchain Broken? ++
Timestamping ++
Mining, Mining, Mining - What's Your Hash Rate? ++
Bitcoin, Bitcoin, Bitcoin ++
(Crypto) Block with Transactions (Tx)_

Mastering Ethereum - Building Contract Services and Decentralized Apps on the Blockchain (https://github.com/ethereumbook/ethereumbook) -
by Andreas M. Antonopoulos, Gavin Wood, 2018 - FREE (Online Source Version)
_What is Ethereum ++
Introduction ++
Ethereum Clients ++
Ethereum Testnets ++
Keys and Addresses ++
Wallets	++
Transactions ++
Contract Services ++
Tokens ++
Oracles ++
Accounting & Gas ++
EVM (Ethereum Virtual Machine) ++
Consensus ++
DevP2P (Peer-To-Peer) Protocol ++
Dev Tools and Frameworks ++
Decentralized Apps ++
Ethereum Standards (EIPs/ERCs)_


Building Decentralized Apps on the Ethereum Blockchain (https://www.manning.com/books/building-ethereum-dapps) by Roberto Infante, 2018 - FREE chapter 1 --
_Understanding decentralized applications ++
The Ethereum blockchain ++
Building contract services in (JavaScript-like) Solidity ++
Running contract services on the Ethereum blockchain ++
Developing Ethereum Decentralized apps with Truffle ++
Best design and security practice_

Programming Crypto Blockchain Contracts Step-by-Step Book / Guide ( Beta / Rough Draft ) (https://github.com/openblockchains/programming-cryptocontracts) by Gerald Bauer et al, 2019 - FREE (Online Version) --
_Let's Start with Ponzi & Pyramid Schemes. Run Your Own Lotteries, Gambling Casinos and more on the Blockchain World Computer..._


Programming Cryptocurrencies and Blockchains in Ruby ( Beta / Rough Draft ) (http://yukimotopress.github.io/blockchains)
by Gerald Bauer et al, 2018 - FREE (Online Version) @ Yuki & Moto Press Bookshelf --
_Digital $$$ Alchemy - What's a Blockchain? -
How-To Turn Digital Bits Into $$$ or €€€? •
Decentralize Payments. Decentralize Transactions. Decentralize Blockchains. •
The Proof of the Pudding is ... The Bitcoin (BTC) Blockchain(s)
++
Building Blockchains from Scratch -
A Blockchain in Ruby in 20 Lines! A Blockchain is a Data Structure  •
What about Proof-of-Work? What about Consensus?   •
Find the Lucky Number - Nonce == Number Used Once
++
Adding Transactions -
The World's Worst Database - Bitcoin Blockchain Mining  •
Tulips on the Blockchain! Adding Transactions
++
Blockchain Lite -
Basic Blocks  •
Proof-of-Work Blocks  •
Transactions
++
Merkle Tree -
Build Your Own Crypto Hash Trees; Grow Your Own Money on Trees  •
What's a Merkle Tree?   •
Transactions
++
Central Bank -
Run Your Own Federated Central Bank Nodes on the Blockchain Peer-to-Peer over HTTP  •
Inside Mining - Printing Cryptos, Cryptos, Cryptos on the Blockchain
++
Awesome Crypto
++
Case Studies - Dutch Gulden  • Shilling  • CryptoKitties (and CryptoCopycats)_



Blockchain for Dummies, IBM Limited Edition (https://www.ibm.com/blockchain/what-is-blockchain.html) by Manav Gupta, 2017 - FREE (Digital Download w/ Email) --
_Grasping Blockchain Fundamentals ++
Taking a Look at How Blockchain Works ++
Propelling Business with Blockchains ++
Blockchain in Action: Use Cases ++
Hyperledger, a Linux Foundation Project ++
Ten Steps to Your First Blockchain application_


Get Rich Quick "Business Blockchain" Bible - The Secrets of Free Easy Money (https://github.com/bitsblocks/get-rich-quick-bible), 2018 - FREE --
_Step 1: Sell hot air. How? ++
Step 2: Pump up your tokens. How? ++
Step 3: Revolutionize the World. How?_


Best of Bitcoin Maximalist - Scammers, Morons, Clowns, Shills & BagHODLers - Inside The New New Crypto Ponzi Economics (https://github.com/bitsblocks/bitcoin-maximalist) by Trolly McTrollface, et al, 2018 - FREE

Crypto Facts - Decentralize Payments - Efficient, Low Cost, Fair, Clean - True or False? (https://github.com/bitsblocks/crypto-facts) by Nouriel Roubini, David Gerard, et al, 2018 - FREE

Crypto is the Mother of All Scams and (Now Busted) Bubbles - While Blockchain Is The Most Over-Hyped Technology Ever, No Better than a Spreadsheet/Database (https://github.com/bitsblocks/crypto-bubbles) by Nouriel Roubini, 2018 - FREE

IslandCoin White Paper - A Pen and Paper Cash System - How to Run a Blockchain on a Deserted Island (https://github.com/bitsblocks/islandcoin-whitepaper)
by Tal Kol --
_Motivation ++
Consensus ++
Transaction and Block Specification -
Transaction format •
Block format •
Genesis block ++
References_




Blockchain (Lite) Crypto Hash Libraries

Ruby (#ruby) •
JavaScript (#javascript)


Ruby

blockchain.lite (github: openblockchains/blockchain.lite.rb (https://github.com/openblockchains/blockchain.lite.rb),
gem: blockchain-lite (https://rubygems.org/gems/blockchain-lite)) -
build your own blockchain with crypto hashes -
revolutionize the world with blockchains, blockchains, blockchains one block at a time

require 'blockchain-lite'                        
                                                 
b0 = Block.first( "Genesis" )                    
b1 = Block.next( b0, "Transaction Data..." )     
b2 = Block.next( b1, "Transaction Data......" )  
b3 = Block.next( b2, "More Transaction Data..." )
                                                 
blockchain = **b0, b1, b2, b3**                  
                                                 
pp blockchain                                    

will pretty print (pp) something like:

**#<Block:0x1eed2a0                                                                    
  @timestamp     = 1637-09-15 20:52:38,                                                
  @data          = "Genesis",                                                          
  @previous_hash = "0000000000000000000000000000000000000000000000000000000000000000", 
  @hash          = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b">,
 #<Block:0x1eec9a0                                                                     
  @timestamp     = 1637-09-15 21:02:38,                                                
  @data          = "Transaction Data...",                                              
  @hash          = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743", 
  @previous_hash = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b">,
  ...                                                                                  


JavaScript

blockchain.lite (github: openblockchains/blockchain.lite.js (https://github.com/openblockchains/blockchain.lite.js),
npm: blockchain-lite (https://www.npmjs.com/package/blockchain-lite)) -
build your own blockchain with crypto hashes -
revolutionize the world with blockchains, blockchains, blockchains one block at a time

const Blocks = require( "blockchain-lite" )          
                                                     
// use basic block                                   
let Block = Blocks.basic                             
                                                     
let b0 = Block.first( 'Genesis' )                    
let b1 = Block.next( b0, 'Transaction Data...' )     
let b2 = Block.next( b1, 'Transaction Data......' )  
let b3 = Block.next( b2, 'More Transaction Data...' )
                                                     
let blockchain = **b0, b1, b2, b3**                  
                                                     
console.log( blockchain )                            

will log something like:

** Block {                                                                                
    timestamp:     2017-09-25 17:03:38,                                                   
    data:         'Genesis',                                                              
    previousHash: '0000000000000000000000000000000000000000000000000000000000000000',     
    hash:         '08f4fa71628c5bc6b430228738bc8c41afaf508ece0b1cf9c9cac53d02e11829' },   
  Block {                                                                                 
    timestamp:     2017-09-25 17:13:38,                                                   
    data:         'Transaction Data...',                                                  
    previousHash: '08f4fa71628c5bc6b430228738bc8c41afaf508ece0b1cf9c9cac53d02e11829',     
    hash:         '740a4aeb3441484c96d1e7f63d31b716220ccee3b6fe94547cae2afbb6010626' },   
  Block {                                                                                 
    timestamp:     2017-09-25 17:23:38,                                                   
    data:         'Transaction Data......',                                               
    previousHash: '740a4aeb3441484c96d1e7f63d31b716220ccee3b6fe94547cae2afbb6010626',     
    hash:         '28b6892a069e2ff7f1c3128ab495d7cd9b9b1636a51a7f69db93a14b1ee6b1a7' },   
  Block {                                                                                 
    timestamp:     2017-09-25 17:33:38,                                                   
    data:         'More Transaction Data...',                                             
    previousHash: '28b6892a069e2ff7f1c3128ab495d7cd9b9b1636a51a7f69db93a14b1ee6b1a7',     
    hash:         '4cc0329b2c0cb32e0451fa3179bd944d4cd0fcf410939172f979e9fd2aa9f5f3' } ** 


Git, Git, Git - The Stupid Content Tracker with Crypto Hashes

_Everything is local. Distributed is the new centralized._

! (i/xkcd1597.png)


Quotes - Blockchains and Git

▐ Yep, that's the joke. Nobody has been able to explain to me how the "blockchain" buzzword is significantly different to "git repo".
▐ -- Yaakov (https://twitter.com/yaakov_h/status/902659507255312384)
▐ 
▐ But if you said "let's build a currency where all transactions are stored in a git repo"
▐ you wouldn't be taken seriously for even 24 hrs.
▐ -- Yaakov (https://twitter.com/yaakov_h/status/902659847224664064)

▐ Soon explaining git like "a git repo is like a blockchain with commits instead of blocks".
▐ -- Nicolás Berger (https://twitter.com/nicoberger/status/901776907418697729)
▐ 
▐ "A local branch is like a state channel. It can be pushed and merged into the master blockchain at any moment."
▐ -- Nicolás Berger (https://twitter.com/nicoberger/status/901777571456614400)

▐ The #Blockchain has changed the world. Here I make the argument that the #Blockchain is just like #git.
▐ -- Jackson Kelley (https://twitter.com/sjkelleyjr/status/901464041163341824)

▐ git merge **-m REF**  **-g BLOB**  --push
▐  Merge and push all signed commits to the blockchain.
▐ -- Git Commands (https://twitter.com/git_commands/status/935574015015612416)


Books

Learn Enough Git to Be Dangerous (https://learnenough.com/git-tutorial) by Michael Hartl - FREE (Online Version) --
_Getting started ++
Backing up and sharing ++
Intermediate workflow ++
Collaborating ++
Conclusion ++
Advanced setup_


Pro Git (https://git-scm.com/book) by Scott Chacon and Ben Straub, 2nd Edition, 2014 - FREE (Online Version) --
_Getting Started ++
Git Basics ++
Git Branching ++
Git on the Server ++
Distributed Git ++
GitHub ++
Git Tools ++
Customizing Git ++
Git and Other Systems ++
Git Internals ++
A1: Git in Other Environments ++
A2: Embedding Git in your Applications ++
A3: Git Commands_


▐ Git gets easier once you get the basic idea that branches are homeomorphic endofunctors
▐ mapping submanifolds of a Hilbert space.
▐ -- Anonymous


Open Distributed Databases on Git

football.db (https://github.com/openfootball) - open public domain football datasets (incl. clubs, national teams, leagues, match schedules, etc.)

world.db (https://github.com/openmundi) - open public domain world (country) datasets

beer.db (https://github.com/openbeer) - open public domain beer & brewery datasets

▐ Add a beer transaction to the #blockchain on #git and win a free Wiener Lager beer! Cheers. Prost.
▐ -- Gerald Bauer @ Austria Codes (https://twitter.com/austriacodes/status/907240018435088384)



Open Distributed (Hyper) Ledger Books on Git

Shilling (or Schilling) (https://github.com/bitshilling/bitshilling) - Shilling on the Blockchain! - Rock-Solid Alpine Dollar from Austria

Tulips (TULIPS.md) - Tulips on the Blockchain! - Learn by Example from the Real World (Anno 1637) - Buy! Sell! Hold! Enjoy the Beauty of Admiral of Admirals, Semper Augustus, and More



Classic Tulip Mania

_A period in the Dutch Golden Age during which contract prices for bulbs of the recently introduced tulip reached extraordinarily high levels and then dramatically collapsed in February 1637._

! (i/tulipmania-ii.png)


Quotes - Blockchains are the next Internets / Tulips

▐ People who compare digital tokens to tulips are essentially saying digital tokens are a bubble backed
▐ by nothing but pure hype and speculation.
▐ 
▐ What they fail to understand is that tulips come from dirt, not a blockchain.
▐ 
▐ And as we all know, blockchain is possibly the best technological innovation since the internet.
▐ It will have a tremendous impact on global business and society in general.
▐ -- TulipToken (http://tuliptoken.com)


Books

Tulipomania: The Story of the World's Most Coveted Flower & the Extraordinary Passions It Aroused by Mike Dash, 2001 --
_A Mania for Tulips ++
The Valley of Tien Shan ++
Within the Abode of Bliss ++
Stranger from the East ++
Clusius ++
Leiden ++
An Adornment to the Cleavage ++
The Tulip in the Mirror ++
Florists ++
Boom ++
At the Sign of the Golden Grape ++
The Orphans of Wouter Winkel ++
Bust ++
Goddess of Whores ++
At the Court of the Tulip King ++
Late Flowering_

Tulipmania: Money, Honor, and Knowledge in the Dutch Golden Age by Anne Goldgar, 2007  --
_Something Strange ++
Art & Flowers ++
Bloemisten ++
Grieving Money ++
Bad Faith ++
Cabbage Fever ++
Glossary ++
A Note on Money_

! (i/tulipmania.png)


Breaking News: CryptoKitties (Yes, Cute Little Cartoon Cats) on the Blockchain!

Collectible. Breedable. Adorable.

Collect and breed digital cats. Start meow. Buy! Sell! Hold!

Learn more @ cryptokitties.co (https://cryptokitties.co)


! (i/cryptokitties-top10-sales.png)


<!-- note: changed pic; was:
   ! (i/cryptokitties.png)
  -->

Latest (and Greatest) Investment Opportunity!

▐ Blockchain has unlocked the magic of digital scarcity, and combining that with the power of
▐ making the digital goods persistent gives them a potential value that is only limited by how much
▐ prestige a wealthy person might place on ownership of the item.
▐ 
▐ -- Justin Poirier (https://twitter.com/tokenizedcap/status/938460753589424128)‏

▐ All I want for Christmas is a CryptoKitty.
▐ 
▐ -- Kayla Williams (https://twitter.com/kaylaw/status/938590748655550464)

▐ I got a fever. And the only prescription is more CryptoKitties.
▐ 
▐ -- Eduardo Salazar (https://twitter.com/ceduardosalazar/status/938558630663634944)

▐ My Gen 7 CryptoKitty #104375. The Future is Meow.
▐ 
▐ -- Anshul Dhawan (https://twitter.com/TheAnshulDhawan/status/938551642202324993)


! (i/cryptokitties-genes01.png)

▐ - Fabulous Persian Spock Gerbil Gold Cottoncandy - Extremely rare gen 5 swift virgin | 2.9 ETH
▐ - Rarity: 0.00264% Gen 5 JAGUAR FABULOUS GOLD DALI!! VIRGIN!
▐ - Rarity: 0.0015% Princess Bubblegum is now for sale! Gen 12 | Brisk | Virgin | Chartreux | Bubblegum | Otaku | Emeraldgreen | Saycheese | Mauveover | Spock - Starts ETH 20/Ends ETH 10
▐ - Gold ducat, Gen 5, Virgin, Swift. Very cheap
▐ - Cheap Gen 1 cute kittie with rare genes! Only 0.125 ETH
▐ - UNIQUE Virgin Peach Googly Gold Mauveover gen:2 cooldown:1 0.87992% RARE
▐ - SUPER CHEAP: Gerbil, Ragdoll, Scarlet, Chestnut, Cotton Candy!!! 0.02 ETH (~$14)
▐ - I'm giving away a Gen 1 FAST Gold for free...
▐ 
▐ -- CrypoKittiesMarket (https://www.reddit.com/r/CryptoKittiesMarket)

Awesome CryptoKitties (and CryptoCopycats)

! (i/cryptokitties-modernart-paintings.png)

A collection about Awesome CryptoKitties (Yes, Cute Little Cartoon Cats) on the Blockchain! and CryptoCopycats - digital collectibles secured on a distributed public databases w/ crypto hashes. Are CryptoPuppies the new CryptoKitties? Learn by 
Example from the Real World (Anno 2017) - Buy! Sell! Hodl!

More @ cryptocopycats/awesome-cryptokitties (https://github.com/cryptocopycats/awesome-cryptokitties)

! (i/cryptokitties-modernart-paintings-iii.png)



Events, Meetups, Orgs

_Revolutionize the world one country at a time. Blockchainers of the world, unite!_

- Blockchain Austria • Blockkette Österreich (https://github.com/austriacodes/blockchain-austria) -- distributed centralized page for blockchain meetups & orgs in Austria (Central Europe)



Awesome Awesomeness

_A curated list of awesome lists._

- Blockchain Stuff (https://github.com/Xel/Blockchain-stuff) -- a curated list of blockchain and general cryptocurrency resources
- Blockchain Roadmap (https://roadmap.sh/blockchain) -- a step-by-step roadmap / guide to become a blockchain programmer
- Awesome Blockchain (https://github.com/igorbarinov/awesome-blockchain) by Igor Barinov et al -- a curated list of the bitcoin blockchain services
- Awesome Blockchain (https://github.com/imbaniac/awesome-blockchain) by Tim Reznich et al -- a curated list of blockchain services and exchanges
- Awesome Blockchain (https://github.com/istinspring/awesome-blockchain) by istinspring et al -- a curated list of awesome projects and services based on blockchain technology
- Awesome Coins (https://github.com/kennethreitz/awesome-coins) by Kenneth Reitz et al -- a guide to crypto-currencies and their algos
- Awesome CryptoKitties (and CryptoCopycats) (https://github.com/openblockchains/awesome-cryptokitties) by Gerald Bauer et al -- a curated list about the awesome crypto kitties and copycats
- Awesome Git (https://github.com/dictcp/awesome-git) by Dick Tang et al -- a curated list of amazingly awesome Git tools, resources and shiny things
- Awesome (https://github.com/sindresorhus/awesome) by Sindre Sorhus et al -- a curated list of awesome lists



Meta

License

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The awesome list is dedicated to the public domain. Use it as you please with no restrictions whatsoever.

blockchains Github: https://github.com/openblockchains/awesome-blockchains