# 5.3.5 EdDSA verification has its own clause

The verification subclause gains a pointer: for EdDSA the verification mechanism is in 6.13. That is a routing instruction. A verifier that runs the generic recompute path for every mechanism will miss the decoding and range checks that EdDSA requires before the group equation.

## What it asks

Route EdDSA verification to its own clause in the verifier dispatch, and confirm with a test that presents an EdDSA signature. The test exists so that the generic path cannot silently accept a signature that the EdDSA rules would reject.

## What the amendment does

Adds a sentence at the end of 5.3.5.

## Who it binds

The verifier owner and the test owner.

## Evidence an auditor samples

- The verifier dispatch table, one row per mechanism and its clause (design note)
- The negative tests that present malformed EdDSA input (test suite)
- The interoperation record with a counterparty verifier (integration report)

## The test you can run

Present a signature with a corrupted encoding and one with an out of range value. If either is accepted, the generic path is still answering for EdDSA.

## Common failures

- The dispatch is added but no negative test proves it is used.
- A library routes internally, and the estate assumes that removes the need to test.

## How to close it

A routing change is a security change. Name the clause in the dispatch table, add the two negative cases, and keep the test next to the code so that a library upgrade cannot quietly change the answer.

## Source

ISO/IEC 14888-3:2018/FDAM 1:2026(en), draft, 5.3.5. Read on 21 October 2026. Our wording, not the instrument's.
https://www.iso.org/standard/89517.html

Not legal advice; does not certify.