GlossaryAdvanced
Avalanche Effect
A property of a good hash function where changing even a single bit of input produces a completely different, unpredictable output.
The avalanche effect describes a property of a well-designed hash function (see Kaavon's "Hash Function" glossary definition): changing even a single bit of the input produces a completely different, unpredictable output, with roughly half of the output bits flipping on average.
This property is specifically what makes a hash function useful for detecting even tiny, unintentional data changes, and what makes it computationally infeasible to work backward from a desired output to find an input that produces it.
Examples
- Changing a single character in a large document produces a completely unrelated hash output, a direct demonstration of the avalanche effect.
- The avalanche effect is part of why a hash function can reliably detect even the smallest unintentional data corruption.