frost_serialization.md

FROST Messages & Data Serialization

The following document describes the byte-level structure of messages sent in FROST [1]. Each message consists of a header of fixed size followed by the actual payload of the message.

Headers

All messages have the following header:

Bytes	Field name	Data type
1	Message type	u8
1	Version	u8
2	Sender ID	u16
2	Receiver ID	u16

The Message type and Version fields specify the payload that follows after the header. The sender is uniquely identified by the Sender ID 1 field and the receiver is uniquely identified by the Receiver ID 1 field.

Payloads

Messages in FROST are split into three general domains. The following sections describe each domain and its messages.

Key Generation with DKG

These messages are sent during the Distributed Key Generation (DKG).

Round One

Broadcast the public commitment vector and the proof of knowledge .

Header:

Message type	Version
1	1

Payload:

Bytes	Description	Data type
2	Length t of the commitment vector	u16
512 . t	Individual commitments	[AffinePoint; t]
256	The value R	Scalar
256	The value u	Scalar

Round two

Broadcast the secret shares f (l).

Header:

Message type	Version
2	1

Payload:

Bytes	Description	Data type
256	Secret share f (l)	Scalar

Key Generation with Dealer

Header:

Message type	Version
3	1

Payload:

Bytes	Description	Data type
		Scalar