openid / openid/OpenID4VCI

Additional options for wallet-provided nonces for PoP

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Description

On the DCP WG call on June 27th, we concluded that c_nonce is in fact optional. To mitigate the attack discussed here https://github.com/openid/OpenID4VCI/issues/19 without a c_nonce, several options were brought up and we agreed to create a dedicated issue for this.

Some options are:

  1. ath (access token hash)
  2. jti (chosen by the wallet with enough entropy)
  3. nonce (keep nonce in PoP but allow wallet-generated nonces similar to jti; probably not a good idea because in some situations/policies a server might fail distinguishing between c_nonce values and wallet-generated nonces in the nonce claim)

(cc @David-Chadwick @Sakurann @jogu @bc-pi @babisRoutis)

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

This issue names no repository files, tests, or implementation entry points. Start by reading the linked OpenID4VCI issue and the June 27 DCP WG discussion, then compare the ath, jti, and wallet-generated nonce options against the c_nonce attack. Done means an agreed protocol option and clearly specified normative changes.

Written by the indexing model from the issue text.

Assessment

Domain
authentication, security
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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