# 6.1 The environment for a prime order group

The environmental clause fixes the domain parameters, the authenticity of the public key and the trust a verifier places in the group. Because the arithmetic is short, the security rests almost entirely on the group being sound and on the verifier using the right one.

## What it asks

Evidence the group parameters, their distribution and the verifier trust path, and show that the group in use matches the group in the record. Where a domain shares parameters, record the authority that generated them and the date of the last review.

## What the revision does

The fourth edition will restate these conditions. The revised wording is not public.

## Who it binds

The domain authority and the verifier operator.

## Evidence an auditor samples

- The group parameter set, with generation and distribution records (cryptography standard)
- The verifier configuration that names the group (configuration management database)
- The review date for the group (review log)

## The test you can run

Compare the group in the verifier configuration with the group in the standard. A mismatch is a finding even if both groups are sound.

## Common failures

- The verifier accepts any group the claimant names.
- The group review date predates the last change to the deployment.

## How to close it

Pin the group in configuration and test the pin. A verifier that accepts a claimant supplied group has moved the security decision to the claimant, which the clause does not allow.

## Source

ISO/IEC 9798-5:2009(E), 6.1, 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.