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Last active December 16, 2021 12:35
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DLTs, Blockchains, crypto stuff and friends
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note.md

Bitcoin

  • proof of work
  • uses UTXOs

Ethereum

  • proof of work, looks to change in 2.0 for proof of stake (the network is secured by the owners of tokens)
  • uses a global state for "externaly owned" accounts, and a storage for each smart contract (state acount)

Radix

  • uses UTXs
  • not a blockchain, not a DL: "uses both the passage of logical time and database sharding to create an immensely secure and scalable system for the shared storage and accessing of data"
  • https://www.radixdlt.com/

IOTA

  • each user must validate two transactions in order to include one
  • do not use a traditional blockchain technology, but a DAG, allowing multiple chains of transactions to co-exist and interconnect
  • project "Coordicide" to remove the centralized coordinating node owned by the foundation
  • https://www.iota.org/
  • "An Open, Feeless Data and Value Transfer Protocol"

Perlin

  • Web assembly smart contract
  • Fast DL
  • https://wavelet.perlin.net/
  • "An open ledger for writing scalable, mission-critical, decentralized WebAssembly applications."

hedera

Substrate

Notes on Bitcoin

  • Every node keeps a mempool, which is a pool of transaction
  • A user submit his transaction to a node, which will dispatch it to the other nodes
  • Nodes decide what transaction they want to include in their block, logically taking the ones with the highest fees
  • Users define the fee they are willing to pay for a transaction
  • The nonce generate ~4 billions hash possiblities, but the range of possible hashes with 18 leading zeros is arounnd 1e55, thus they migh not exist a required nonce to solve the PoW problem
  • If the 4 billions possibilities does not find a solution, the node can change the transaction it includes, or wait for the next timestamp
  • In a 51% attack, a separate group of nodes builds a competing chain that will eventually be longer. Revealing this longer chain will force the honnest nodes to update their chain and abandon previous blocks, which will invalidate the transactions in those blocks. Attackers leverage the double-spend problem.
  • There will be a maximum of 21 millions bitcoin by 2140
  • with 18 leading zeros, a probability that a hash is valid is 0.00000000000000000002%
  • a wallet balance is the total amount of UTXOs
  • A bitcoin address is the sha256 of the public key
  • we can use either the public key or the address to send money, but it is better to use the adderss to not reveal the public key
  • Segwit block introduce a soft fork to increase the number of transactions per block. Since a block is limited to 1Mb, Segwit doesn't store the scriptSig of a transaction inside the transaction
  • Transaction fee is the difference between the input and the output of the transaction, ie. the money not spent
  • What makes a blockchain a cryptocurrency? Answer: transactions
  • Transaction first exist outside of a block. Then, when a miner wins the puzzle, it includes the transaction into a block
  • The consensus is used to ensure that all the nodes have the same blockchain
  • Ethereum was created because bitcoin can not run turing-complete code on the blockchain. Bitcoin script lacks the notion of loops to make it turing complete
  • A smart contract can be seen as a program that runs on the blockchain
  • Bitcoin CASH is a hard fork that increased block size to 8Mb (1 august 2017)
  • Bitcoin Gold is a hard fork to be ASIC resistant (24 oct 2017) and keep GPU mining
  • Ethereum classic is the unaccepted fork (20 july 2016) to fix the DAO attack
  • A hard fork is when it "relaxes" the rules, which results in a non-backward compatible change
  • A soft fork is when it "tightens" the rules, which results in a backward compatible change

Ripple

  • a fast and cheap crypto currency
  • offers instant and direct transfer
  • possible trear to Western Union
  • does not depensd on the ripple company
  • can be used for any currency exchange
  • do not use huge amount of electricity to mine
  • anyone can run a server and be a validator

Neo

  • the Chinees version of ethereum
  • uses dBFT concensus protocol

Litecoin

  • crypto currency like Bitcoin
  • faster than bitcoin
  • compatible with blocknet
  • easier to mine with a GPU
  • meant to be the sylver version of gold Bitcoin

Cardano

  • A distributed ledger
  • first blockchain plateform to evovle out of a scientific philosophy and research approach
  • Has a Ada blockchain
  • Built with layers
  • Use Proof of Stake: a node is selected as leader with a probability corresponding to its amount of coin it has

Stellar

  • released in 2014, decentralized payment network and protocol
  • Lumen coins
  • was originally based on Ripple's protocol

https://slock.it/

  • connects devices to the blockchain
  • the "economy of things"

Algorand

  • permissionless proof-of-stake blockchain

Centrifuge

OMEN

  • an information platform, where you can bet your money in information and expected outcome

Cosmos

  • https://cosmos.network/
  • connects blockchains with cross-chain transaction
  • the "cosmos network"
  • author of the Tendermint BFT protocol

Spacemesh

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