There is a huge hole here. Revocation of (for example) driving
privileges should not impact the use of the cred for other purposes.
The revocation idea can lead to cancelation of the person. Some that
violates the fundamental rights of human beings. Revocation is
basically discrimination.
thx ..Tom (mobile)
On Fri, Mar 29, 2024, 2:50 AM Denis <denis.i...@free.fr> wrote:
This thread is related to the three roles model, i.e, Holder,
Issuer and Verifier.
However, I also copy this email to the OAuth WG, since it is
currently developing draft-ietf-oauth-status-list.
Thanks to Orie for providing the second link:
https://gitlab.opencode.de/bmi/eudi-wallet/eidas-2.0-architekturkonzept/-/blob/main/architecture-proposal.md?ref_type=heads#ocsp-stapling.
What first follows a copy/paste of some parts of the "Architecture
Proposal for the German eIDAS Implementation". Then after, my
observations follow.
Various use cases and scenarios may require revocation:
* the PID/(Q)EAA Provider wants to revoke its issued
credential because the contained data is no longer valid
* the Wallet Provider wants to revoke a Wallet Instance
because Wallet Security Cryptographic Device (WSCD)
or the Wallet Instance application is compromised or
vulnerable
* the user wants to revoke their Wallet Instance because
they lost their smartphone
* the user wants to revoke their PID
* the PID Provider wants to revoke a PID because the person
has died
To enable revocation within the EUDI Wallet ecosystem, the
following mechanisms for revocation are considered:
(a) Certificate Revocation Lists
(b) Status Lists
(c) Online Certificate Status Protocol (OCSP)
(d) OCSP stapling
*My observations:*
For case (a): "CRLs have seen some scalability limitations in
the Browser TLS context, and
it remains open to evaluate if CRL sizes remain manageable
within the eIDAS ecosystem".
For case (b): "it remains open to evaluate if this is
sufficient for the eIDAS ecosystem".
For case (c): "Therefore, usage of OSCP is /not/ recommended".
For case (d): "a proposal applying the concepts to the PID
credential formats is under development
<https://datatracker.ietf.org/doc/draft-demarco-oauth-status-attestations/>.
[i.e., draft-demarco-oauth-status-attestations-00]
the concept has the privacy potential as the Relying Party
does not fetch the revocation information itself".
draft-demarco-oauth-status-attestations-00 looks interesting.
Presently, this draft does not include a privacy considerations
section. It is thus questionable whether it is able to support the
unlinkability property
[it cannot be distinguished whether two transactions are related
to the same user or not].
Some nice characteristics are :
* "the Relying Party does not fetch the revocation information
itself".
* "both the wallet and the verifier work without internet
connectivity during the presentation phase".
But what about a mechanism where, in addition, the holder does not
fetch the revocation information itself ?
Yes, neither the holder, nor the verifier, fetch itself any
revocation information.
Is it "mission impossible"? No, it isn't.
A Wallet Provider is in a position to suspend (i.e., which is
equivalent to a temporary revocation) any digital credential
placed in a Wallet Instance.
It is also in a position to invalidate the use of a Wallet
Instance or to remove any digital credential placed in a Wallet
Instance (which is equivalent
to a definitive revocation).
A Wallet instance is THE Holder, i.e., an application that needs
to be a Trusted Application (TA) running in a TEE. Every time the
holder (application)
is online, it can transparently connect to the Wallet Provider. If
instructed by a Credential Issuer, aWallet Provider can suspend
any digital credential
issued by that Credential Issuer.
The digital credentials placed in a Wallet Instance will only be
usable if the Wallet Instance has been online during, e.g., the
last 24 or 36 hours.
From a holder point of view (or a Wallet Instance point of view),
each time it is online, it will connect to its Wallet Provider.
If no digital credential needs to be suspended, then all the
digital credentials will be usable during the next 24 or 36 hours,
but no longer.
The query made by the Wallet Instance to its Wallet Provider can
be transparently repeated, e.g., every hour. If a suspension is
requested
by a Credential Issuer while the Wallet Instance is online, the
suspension will occur at latest within, e.g., the next hour.
The same mechanism can also be used to revoke the Wallet Instance
when the individual lost his smart phone.
All the other approaches would require the revocation (or the
suspension) of each digital credential, one by one.
This approach avoids to define new data structures that would need
to be exchanged between a Holder and a Verifier or fetched by a
Verifier.
This approach would be fully privacy preserving. In particular,
the unlinkability property will be supported.
Note also that a suspension is much better than a revocation; for
example, if a lost smart phone is found again by the legitimate
individual.
With this flexibility, the individual will no more necessarily ask
for an immediate revocation which has sad consequences in terms of
availability.
The suspension state allows to recover the use of the wallet,
e.g., within the same day. Whereas an individual was afraid of
the consequences
of the revocation, he will not be afraid of the consequences of a
(temporary) suspension. This allows to reduce the risks and hence
to improve
the security level.
eIDAS 2.0 does not currently allow the suspension state. Once,
that approach will be known, maybe the eIDAS.2.0 draft will be
modified.
It is only a draft at this moment.
Denis
Orie - this is great work. I definitely think that scoping out
how this approach could be used with SD-CWT could be an important
part of documenting the architecture.
Mike Prorock
Founder
https://mesur.io/
On Thu, Mar 28, 2024 at 12:53 PM Orie Steele
<orie@transmute.industries> <mailto:orie@transmute.industries> wrote:
Hello,
At IETF 119 OAUTH session, I shared some alternative
solutions to the "dynamic credential state" or "suspension
and revocation problem", in digital credentials.
https://datatracker.ietf.org/doc/draft-demarco-oauth-status-attestations
This approach offers some advantages and disadvantages over
status lists / CRL type dynamic state mechanisms that need to
be fetched over a network by relying parties, or fetched by
holders and presented alongside the credentials they monitor.
The primary improvements are:
1. Reduce implementer burden for relying parties, many of
which might be forbidden from calling out to networks.
2. Eliminate the bitstring status list, which can include
decoy / dummy values that can be used to track relying
parties, or that communicate or update state for credentials
which are not relevant to the transaction.
There is some interesting commentary on this approach here:
https://gitlab.opencode.de/bmi/eudi-wallet/eidas-2.0-architekturkonzept/-/blob/main/architecture-proposal.md?ref_type=heads#ocsp-stapling
Which you might all find interesting.
As a general comment, CRLs and OCSP can both address
revocation use cases and approaches in JOSE and COSE, and
applications of this approach to SD-CWT or SCITT Receipts are
particularly interesting to consider.
Regards,
OS
--
ORIE STEELEChief Technology Officerwww.transmute.industries
<http://www.transmute.industries>
<https://streaklinks.com/B6DNq7fQ0K3-fblaFg95UjF6/https%3A%2F%2Ftransmute.industries>
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