Draft: draft-ietf-mls-architecture

Commentary: Remove " join an existing group " from architecture doc , based on UserAdd having been removed from the protocol doc . Remove statement that message delivery can not be correlated between AS identities and DS delivery channels . This seems generally very difficult to achieve . It may be possible at times , but does not seem to be grounded in discussions that we have had at the working group meetings . Note that federation requires compatible wire encodings . Note that communication with the AS requires TLS or alternative authentication . Note that out - of - band channels may facilitate detection of misbehaviour . Some grammar fixes .
The protocol aims to be compatible with federated environments.
While this document does not specify all necessary mechanisms
required for federation, multiple MLS implementations can
interoperate and to form federated systems.
The protocol aims to be compatible with federated environments.
While this document does not specify all necessary mechanisms
required for federation, multiple MLS implementations can
interoperate and to form federated systems if they use compatible
wire encodings.
We assume that all transport connections are secured via some
transport layer security mechanism such as TLS I-D.ietf-tls-tls13.
However, as noted above, the security of MLS will generally survive
compromise of the transport layer.
We assume that all transport connections are secured via some
transport layer security mechanism such as TLS I-D.ietf-tls-tls13.
However, as noted above, the security of MLS will generally survive
compromise of the transport layer, so long as identities provided by
the AS are authenticated at a minimum.
A corollary to this statement is that the AS and the DS cannot read
the content of messages sent between Members as they are not Members
of the Group.  MLS optionally provide additional protections
regarding traffic analysis so as to reduce the ability of
adversaries, or a compromised member of the messaging system, to
deduce the content of the messages depending on (for example) their
size.  One of these protections includes padding messages in order to
produce ciphertexts of standard length.  While this protection is
highly recommended it is not mandatory as it can be costly in terms
of performance for clients and the MS.
A corollary to this statement is that the AS and the DS cannot read
the content of messages sent between Members as they are not Members
of the Group.  MLS optionally provides additional protections
regarding traffic analysis so as to reduce the ability of
adversaries, or a compromised member of the messaging system, to
deduce the content of the messages depending on (for example) their
size.  One of these protections includes padding messages in order to
produce ciphertexts of standard length.  While this protection is
highly recommended it is not mandatory as it can be costly in terms
of performance for clients and the MS.
In general we do not consider Denial of Service (DoS) resistance to
be the responsibility of the protocol.  However, it should not be
possible for anyone to perform a trivial DoS attack from which it is
hard to recover.
In general we do not consider Denial of Service (DoS) resistance to
be the responsibility of the protocol.  However, it should not be
possible for anyone aside from the DS to perform a trivial DoS attack
from which it is hard to recover.
However, a DS can mount a variety of DoS attacks on the system,
including total DoS attacks (where it simply refuses to forward any
messages) and partial DoS attacks (where it refuses to forward
messages to and from specific Clients).  As noted in delivery-
guarantees, these attacks are only partially detectable by clients.
Ultimately, failure of the DS to provide reasonable service must be
dealt with as a customer service matter, not via technology.
However, a DS can mount a variety of DoS attacks on the system,
including total DoS attacks (where it simply refuses to forward any
messages) and partial DoS attacks (where it refuses to forward
messages to and from specific Clients).  As noted in delivery-
guarantees, these attacks are only partially detectable by clients
without an out-of-band channel.  Ultimately, failure of the DS to
provide reasonable service must be dealt with as a customer service
matter, not via technology.