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The Bitcoin School
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Start the JourneyLooking for one thing? The glossary explains 505 Bitcoin terms in plain language.
Plain language. Sourced chapters. Live on-chain data from a real node. Huge glossary, Rabbit Holes, and one opinionated Journey from "what is money?" to running a full node. No altcoins, no affiliate links, and no signup needed to read any of it.
From the glossary
12 or 24 English words (BIP-39) that encode a Bitcoin wallet's master secret. The complete backup; lose it and you lose the coins, leak it and someone else has them.
Read full entryNew on the site.
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Rabbit Hole · Beginner · 21 min
Brain Wallets: Why a Passphrase You Made Up Is a Key Someone Can Guess
A brain wallet turns a phrase you made up into a Bitcoin private key, and since at least 2013 programs have guessed such phrases and emptied the wallets. In February 2014 James D'Angelo funded three of them on video. The chain shows what happened to his coins and to the famous phrases, and the best-known site closed in 2015.
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Rabbit Hole · Advanced · 16 min
The Time Warp: How Lying About the Time Could Break Bitcoin's Difficulty
A seam in Bitcoin's 2009 code would let a miner with most of the hash rate drive difficulty to its minimum within weeks, in under six with all of it. It has been used on other coins and planted once on testnet, never used on Bitcoin, and the fix is written and waiting for a soft fork.
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Rabbit Hole · Intermediate · 14 min
Quindecillions: Why Nobody Can Stumble on Your Bitcoin
After a vanity address search, readers ask whether the address already had coins in it and how many wallets the search found on the way. Every Bitcoin address is a drawer. There are about 1.5 x 10^48 of them, 57 million hold coins, and no search on record has landed on a funded one by chance. The same arithmetic is why nobody has to register a key before using it.
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It is about 154 vB: 10.5 vB of overhead, a 57.5 vB key-path input and two 43 vB outputs, by Bitcoin Optech's size calculator. 110 vB is the size with one output. The entry and its Spanish edition now say about 154 vB and 1,540 sats, and the calculator is listed in the sources.
What was wrong -
BIP 173 leaves 1, b, i and o out of the data part; l and 0 are in it. The QR saving comes from uppercase: a bech32 address never mixes case, so it can go into a QR code in uppercase and use the alphanumeric mode, which the BIP puts at 45% more compact than the byte mode a mixed-case Base58 address needs. The BIP's authors are Pieter Wuille and Greg Maxwell. The entry now says so and lists BIP 173 and BIP 350 in its sources.
What was wrong -
The Time Warp: How Lying About the Time Could Break Bitcoin's Difficulty
Satoshi's announcement, "Bitcoin v0.1 released", reached the Cryptography Mailing List on January 8, 2009 (14:27 EST, 19:27 UTC). The chapter and its Spanish edition now say the 8th, and the announcement is listed in the sources.
What was wrong