Credential validation

Credential validation is a process that allows a member to verify the validity of the credentials of other members in the group. The process is described in detail in the MLS protocol specification.

In practice, the application should check the validity of the credentials of other members in two instances:

• When joining a new group (by looking at the ratchet tree)
• When processing messages (by looking at a add & update proposals of a StagedCommit)