Struct vodozemac::megolm::GroupSession

pub struct GroupSession { /* private fields */ }

A Megolm group session represents a single sending participant in an encrypted group communication context containing multiple receiving parties.

A group session consists of a ratchet, used for encryption, and an Ed25519 signing key pair, used for authenticity.

A group session containing the signing key pair is also known as an “outbound” group session. We differentiate this from an inbound group session where this key pair has been removed and which can be used solely for receipt and decryption of messages.

Such an inbound group session is typically sent by the outbound group session owner to each of the receiving parties via a secure peer-to-peer channel (e.g. an Olm channel).

Implementations

impl GroupSession

pub fn new(config: SessionConfig) -> Self

Construct a new group session, with a random ratchet state and signing key pair.

pub fn session_id(&self) -> String

Returns the globally unique session ID, in base64-encoded form.

A session ID is the public part of the Ed25519 key pair associated with the group session. Due to the construction, every session ID is (probabilistically) globally unique.

pub fn message_index(&self) -> u32

Return the current message index.

The message index is incremented each time a message is encrypted with the group session.

pub fn session_config(&self) -> SessionConfig

pub fn encrypt(&mut self, plaintext: impl AsRef<[u8]>) -> MegolmMessage

Encrypt the plaintext with the group session.

The resulting ciphertext is MAC-ed, then signed with the group session’s Ed25519 key pair and finally base64-encoded.

pub fn session_key(&self) -> SessionKey

Export the group session into a session key.

The session key contains the key version constant, the current message index, the ratchet state and the public part of the signing key pair. It is signed by the signing key pair for authenticity.

The session key is in a portable format, suitable for sending over the network. It is typically sent to other group participants so that they can reconstruct an inbound group session in order to decrypt messages sent by this group session.

pub fn pickle(&self) -> GroupSessionPickle

Convert the group session into a struct which implements serde::Serialize and serde::Deserialize.

pub fn from_pickle(pickle: GroupSessionPickle) -> Self

Restore a GroupSession from a previously saved GroupSessionPickle.

pub fn from_libolm_pickle( pickle: &str, pickle_key: &[u8] ) -> Result<Self, LibolmPickleError>

Available on crate feature libolm-compat only.

Trait Implementations

impl Default for GroupSession

fn default() -> Self

Returns the “default value” for a type.

impl From<&GroupSession> for InboundGroupSession

fn from(session: &GroupSession) -> Self

Converts to this type from the input type.

impl From<GroupSessionPickle> for GroupSession

fn from(pickle: GroupSessionPickle) -> Self

Converts to this type from the input type.