the.com/avalanche effect
Flip one bit in, flip half the bits out — crypto's way of saying no small talk.
means A design property of hashes and ciphers where changing even a single input bit scrambles roughly half the output bits, so similar inputs never produce similar-looking outputs.
from The term borrows its imagery straight from the mountainside: a small disturbance — one pebble, one bit — triggering a cascade wildly disproportionate to its size. It entered cryptographic vocabulary in the mid-20th century as designers like Horst Feistel and later Claude Shannon-influenced cipher theorists studied 'diffusion,' the principle that small input changes must spread widely through the output. The word 'avalanche' itself traces back through French to Old French 'lavanche,' describing the snow-slide phenomenon long before cryptographers ever needed a metaphor for chaos triggered by a single flipped bit.
- origin
- coined by Horst Feistel in cipher design
- threshold
- good hash flips ~50% of output bits
- purpose
- stops attackers from guessing inputs via patterns
- fails without it
- similar inputs leak similar outputs