Glossary · Security

ECB

Electronic Code Book

In plain language

The simplest way to scramble data in blocks, where identical pieces of data always scramble to the same result.

The metaphor

Like swapping each word in a letter for a fixed code word: repeated phrases show up as repeated codes, so the pattern shows through.

Going deeper

How it works

Data is split into blocks and each block is scrambled separately with the same key.
Two identical blocks produce two identical scrambled blocks, which leaks patterns.
Modern tools use other modes that avoid this problem.
Seeing it listed as an option is usually a sign of an old or careless setup.

In practice

A security review flags a legacy product that encrypts data in this mode.
An old file encryption tool offers it as a default setting.
A developer is told to switch to a mode that hides repeats.

A question owners ask

Should I worry if a product uses it?

Only if it protects sensitive data. For a small business it rarely comes up, and the fix is to ask the vendor which mode they use and choose a modern one.

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