Short, focused explanations of the ideas behind cryptography and blockchain.
A one-way function that turns any input into a fixed-size fingerprint.
A widely used hash function producing a 256-bit (64 hex character) digest.
A small change in the input produces a completely different hash.
Two different inputs that produce the same hash output.
Scrambling data with a key so only someone holding the matching key can read it.
Encryption where the same key both locks and unlocks the data.
Cryptography with a matched key pair: a public key anyone may use, and a private key only you hold.
A cryptographic proof that a message was created by the holder of a private key and has not been altered.
The protocol that encrypts and authenticates your connection to a website.
A batch of confirmed transactions plus a header that links it to the block before it.
A signed statement that moves value from one address to another, recorded permanently on the ledger.
A tree of hashes that lets you verify that data belongs to a set efficiently.
The process independent nodes use to agree on one canonical history without a central operator.
A consensus mechanism where participants expend computational effort to earn the right to add a block.
A consensus mechanism where validators lock capital and are rewarded or penalised based on honest behaviour.
A number used once — in mining, the counter grinded to satisfy the target; in encryption, a value that must never repeat for a key.
A wallet stores the keys that authorise spends — never the coins themselves, which live on the chain.
An attack where one party controls most of the network's mining power or stake and can rewrite recent history.
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