So, here’s my Top 100 snippets of knowledge for blockchain: Blockchains use public key methods to integrate digital trust. Bob signs for a transaction with his private key, and Alice proves this with Bob's public key. The first usable public key method was RSA — and created by Rivest, Shamir and Adleman. It was first published in 1979 and defined in the RSA patent entitled “Cryptographic Communications System and Method”. Blockchains can either be permissioned (requiring rights to access the blockchain) or permissionless (open to anyone to use). Bitcoin and Ethereum are the two most popular permissionless blockchains, and Hyperledger is the most popular permissioned ledger. Ralph Merkle — the boy genius — submitted a patent on 5 Sept 1979 and which outlined the Merkle hash. This is used to create a block hash. Ralph Merkle’s PhD supervisor was Martin Hellman (famous as the co-creator of the Diffie-Hellman method). David Chaum is considered as founders of electronic payments, and, in 1983, created ECASH, along with publishing a paper on “Blind signatures for untraceable payments”. Miners gather transactions on a regular basis, and these are added to a block and where each block has a Merkle hash. The first block on a blockchain does not have any previous blocks — and is named the genesis block. Blocks are bound in a chain, and where the previous, current and next block hashes are bound into the block. This makes the transactions in the block immutable. Satoshi Nakamoto worked with Hal Finney on the first versions of Bitcoin, and which were created for a Microsoft Windows environment. Craig Steven Wright has claimed that he is Satoshi Nakamoto, but this claim has never been verified. Most blockchains use elliptic curve cryptography — a method which was created independently by Neal Koblitz and Victor S. Miller in 1985. Elliptic curve cryptography algorithms did not take off until 2004. Satoshi selected the secp256k1 curve for Bitcoin, and which gives the equivalent of 128-bit security. The secp256k1 curve uses the mapping of y²=x³ + 7 (mod p), and is known as a Short Weierstrass (“Vier-strass”) curve. The prime number used with secp256k1 is ²²⁵⁶−²³²−²⁹−²⁸−²⁷−²⁶−²⁴−1. Satoshi published a 9-page paper entitled “Bitcoin: A Peer-to-Peer Electronic Cash System” White Paper on 31 Oct 31, 2008. In 1997, Adam Black introduce the concept of Proof of Work of Hashcash in a paper entitled, “Hashcash — a denial of service countermeasure.” This work was used by Satoshi in his whitepaper. Satoshi focused on: a decentralized system, and a consensus model and addressed areas of double-spend, Sybil attacks and Eve-in-the-middle. The Sybil attack is where an adversary can take over the general consensus of a network — and leads to a 51% attack, and where the adversary manages to control 51% or more of the consensus infrastructure. Satoshi used UK spelling in his correspondence, such as using the spelling of “honour”. The first Bitcoin block was minted on 3 Jan 2009 and contained a message of “Chancellor on brink of second bailout for banks” (the headline from The Times, as published in London on that day). On 12 Jan 2009, Satoshi sent the first Bitcoin transaction of 50 BTC to Hal Finney [here]. A new block is created every 7–10 minutes on Bitcoin. In Aug 2023, the total Bitcoin blockchain size is 502 GB. As of Aug 2023, the top three cryptocurrencies are Bitcoin, Ether, and Tether. Bitcoin has a capitalization of $512 billion, Ether with $222 billion, and Tether at $83 billion. The total cryptocurrency capitalisation is $1.17 trillion. The original block size was 1MB for Bitcoin, but recently upgraded to support a 1.5MB block — and has around 3,000 transactions. Currently the block sizes are more than 1.7MB. Bitcoin uses a gossip protocol — named the Lightning Protocol — to propagate transactions. A Bitcoin wallet is created from a random seed value