Module framing

Message framing

This module contains framing-related operations for MLS messages, including validation logic.

The general structure of the framing process in OpenMLS closely follows the design described in Section 7 of the MLS specification. It can be visualized as follows:

                              Proposal        Commit     Application Data
                                 |              |              |
                                 +--------------+--------------+
                                                |
                                                V
                                         FramedContent
                                             |  |                -.
                                             |  |                  |
                                    +--------+  |                  |
                                    |           |                  |
                                    V           |                  +-- Asymmetric
                          FramedContentAuthData |                  |   Sign / Verify
                                    |           |                  |
                                    +--------+  |                  |
                                             |  |                  |
                                             V  V                -'
                                       AuthenticatedContent
                                                |                -.
                                                |                  |
                                                |                  |
                                       +--------+--------+         +-- Symmetric
                                       |                 |         |   Protect / Unprotect
                                       V                 V         |
Welcome  KeyPackage  GroupInfo   PublicMessage    PrivateMessage -'
   |          |          |             |                 |
   |          |          |             |                 |
   +----------+----------+----+--------+-----------------+
                              |
                              V
                          MLSMessage

• MlsMessageIn/MlsMessageOut: Unified message type for incoming & outgoing MLS messages
• ApplicationMessage: Application message received through a ProcessedMessage

Modules

errors

Framing errors.

Structs

ApplicationMessage

Application message received through a ProcessedMessage.

MlsMessageIn

Before use with the MlsGroup API, the message has to be unpacked via extract to yield its MlsMessageBodyIn.

MlsMessageOut

An MlsMessageOut is typically returned from an MlsGroup function and meant to be serialized and sent to the DS.

PrivateMessage

PrivateMessage is the framing struct for an encrypted PublicMessage. This message format is meant to be sent to and received from the Delivery Service.

PrivateMessageIn

PrivateMessage is the framing struct for an encrypted PublicMessage. This message format is meant to be sent to and received from the Delivery Service.

ProcessedMessage

A message that has passed all syntax and semantics checks.

PublicMessage

PublicMessage is a framing structure for MLS messages. It can contain Proposals, Commits and application messages.

PublicMessageIn

PublicMessageIn is a framing structure for MLS messages. It can contain Proposals, Commits and application messages.

Enums

ContentType

MlsMessageBodyIn

MLSMessage (Body)

MlsMessageBodyOut

MLSMessage (Body)

ProcessedMessageContent

Content of a processed message.

ProtocolMessage

Enum containing a message for use with process_message and an MlsGroup. Both PublicMessage and PrivateMessage implement Into<ProtocolMessage>.

Sender

All possible sender types according to the MLS protocol spec.

WireFormat

Wire format of MLS messages.