Cryptography
The math of scrambling and verifying information so only intended parties can read or trust it.
Cryptography predates crypto by millennia, from wartime ciphers to the padlock icon on a banking site. Modern versions rest on math problems that are easy to compute one way and effectively impossible to reverse. That asymmetry is what makes digital secrets hold.
Blockchains lean on two pieces: hash functions, which fingerprint data and link blocks, and public-key cryptography, which proves who authorized a transaction. The 'crypto' in cryptocurrency points here — not to secrecy, but to provable ownership without a trusted middleman.
Related terms
A system using a paired public and private key so anyone can verify a signature only the owner could make.
HashA fixed-length fingerprint produced by running data through a one-way function; any change yields a completely different output.
Digital SignatureA cryptographic proof that a specific keyholder authorized a message, and that it hasn't been altered since.
Private KeyThe secret number that proves ownership of crypto and authorizes spending it; whoever holds it controls the funds.