Struct DeRecMessage 

pub struct DeRecMessage {
    pub protocol_version_major: u32,
    pub protocol_version_minor: u32,
    pub sequence: u32,
    pub channel_id: u64,
    pub timestamp: Option<Timestamp>,
    pub message: Vec<u8>,
}

DeRecMessage is the top-level protocol envelope for all DeRec messages, except ContactMessage which is exchanged out-of-band during pairing.

This message represents the unit of communication between an Owner and a Helper once a secure channel has been established. Every protocol exchange (pairing, sharing, verification, recovery, etc.) is carried inside this envelope.

Security Model

The DeRecMessage envelope itself is not responsible for confidentiality or authenticity. Instead:

• The message field contains encrypted bytes representing the inner message
• Encryption and signing are applied at the payload level prior to transport

Implementations MUST ensure that:

• The inner message is encrypted using the agreed channel keys
• The envelope metadata is treated as untrusted until the payload is verified

Semantics

A DeRecMessage provides:

• protocol versioning information for compatibility handling
• ordering guarantees via a monotonically increasing sequence number
• channel identification for routing and key selection
• a timestamp for replay protection and observability
• an encrypted payload containing exactly one protocol message

The envelope is transport-agnostic and can be delivered over any supported transport (e.g., HTTPS, message queues), as defined by TransportProtocol.

Ordering and Idempotency

Communication follows a request/response pattern:

• The Owner sends a request message
• The Helper replies with a corresponding response

The sequence field is used to:

• enforce message ordering
• detect duplicates or out-of-order delivery
• support replay protection

Implementations SHOULD treat messages as idempotent and be resilient to retries and duplicate deliveries.

Key Rotation

The sequence number may also be used as a trigger for automatic key rotation. When a configured threshold is reached, implementations MAY initiate a key rotation flow to maintain forward secrecy.

Versioning

The protocolVersionMajor and protocolVersionMinor fields allow peers to:

• detect incompatible protocol versions
• apply backward-compatible parsing logic when possible

Implementations MUST define behavior for handling version mismatches.

Payload Encoding

The message field contains encrypted raw bytes. When decrypted, these bytes MUST deserialize into a MessageBody, which contains exactly one concrete protocol message.

The oneof structure ensures that each DeRecMessage carries a single logical operation.

Fields

protocol_version_major: u32

DeRec protocol major version.

Incremented for breaking changes that are not backward compatible.

protocol_version_minor: u32

DeRec protocol minor version.

Incremented for backward-compatible changes such as adding new fields or message types.

sequence: u32

Monotonically increasing message sequence number.

This value increments by 1 for each message sent on a given channel. It is used to:

• enforce ordering
• detect duplicates or missing messages
• support replay protection

Implementations MAY also use this value to trigger automatic key rotation once a predefined threshold is reached.

channel_id: u64

Channel identifier associated with this communication session.

This value uniquely identifies the logical channel between an Owner and a Helper for a given secret. It is established during pairing and used thereafter to:

• route messages to the correct channel state
• select the appropriate cryptographic keys

This MUST match the channelId exchanged during the ContactMessage phase.

timestamp: Option<Timestamp>

Timestamp indicating when the sender created this message.

This value is expressed in UTC and can be used for:

• replay detection
• timeout handling
• logging and observability

Implementations SHOULD NOT rely solely on this value for security-critical decisions without additional protections.

message: Vec<u8>

Encrypted message payload.

This field contains the encrypted bytes of a serialized MessageBody. The encryption scheme and key material are defined by the pairing process and subsequent key management flows.

Upon decryption, this field MUST deserialize into a valid MessageBody containing exactly one protocol message.

Trait Implementations

impl Clone for DeRecMessage

fn clone(&self) -> DeRecMessage

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DeRecMessage

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DeRecMessage

fn default() -> Self

Returns the “default value” for a type.

impl Hash for DeRecMessage

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for DeRecMessage

fn encoded_len(&self) -> usize

Returns the encoded length of the message without a length delimiter.

fn clear(&mut self)

Clears the message, resetting all fields to their default.

fn encode(&self, buf: &mut impl BufMut) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message to a buffer.

fn encode_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message to a newly allocated buffer.

fn encode_length_delimited( &self, buf: &mut impl BufMut, ) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message with a length-delimiter to a buffer.

fn encode_length_delimited_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message with a length-delimiter to a newly allocated buffer.

fn decode(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes an instance of the message from a buffer.

fn decode_length_delimited(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes a length-delimited instance of the message from the buffer.

fn merge(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes an instance of the message from a buffer, and merges it into self.

fn merge_length_delimited(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes a length-delimited instance of the message from buffer, and merges it into self.

impl PartialEq for DeRecMessage

fn eq(&self, other: &DeRecMessage) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for DeRecMessage

impl StructuralPartialEq for DeRecMessage