# Annex B The principles annex, and what it does not promise

Annex B is informative. It sketches the zero-knowledge principles behind the mechanisms and explains why a choice of parameters can take a mechanism outside the strict definition. It is the annex to quote when someone asks whether the mechanism is really zero knowledge.

## What it asks

Use the annex to explain the qualification in the scope, and do not turn an informative explanation into a compliance claim. Where a design note says the mechanism is zero knowledge, cite the scope and this annex together, and state the parameter dependence.

## What the revision does

The fourth edition will update the informative explanation. The revised text is not public.

## Who it binds

The author of the design note and the reviewer of customer claims.

## Evidence an auditor samples

- The design note sentence, with the scope and annex citation (architecture)
- The customer claim review that records the qualification (review log)
- The parameter dependence note for each mechanism (cryptography standard)

## The test you can run

Find a document that calls the mechanism zero knowledge. If it does not mention the parameter dependence, it has turned an informative annex into a promise.

## Common failures

- An informative annex is cited as if it were normative.
- The qualification is dropped in the customer summary.

## How to close it

Keep informative and normative citations in separate columns of the claim review. The distinction is the whole point of the annex, and it is the first thing a careful customer will test.

## Source

ISO/IEC 9798-5:2009(E), Annex B, publisher preview; replaced by ISO/IEC DIS 9798-5, stage 40.20. Read on 21 October 2026. Our wording, not the instrument's.
https://www.iso.org/standard/89516.html

Not legal advice; does not certify.