Struct mpc_engine::primitives::ot::OTSender

pub struct OTSender { /* private fields */ }

The state of the sender

Implementations

impl OTSender

pub fn init( entropy: &mut Randomness, dst: &[u8] ) -> Result<(Self, OTSenderInit), Error>

Generate the first sender message.

Initiates an OT sender by picking a random P256 scalar y and deriving S = yB and T = yS, where B is the P256 base point. These values will later be used to derive encryption keys in the send stage of the protocol. In addition, the domain separation tag dst, which will be used in key generation is stored in the receiver and S is prepared for sending to the receiver by wrapping it in an OTSenderInit message.

pub fn send( &self, left_input: &[u8], right_input: &[u8], selection: &OTReceiverSelect, entropy: &mut Randomness ) -> Result<OTSenderSend, Error>

Generate the second sender message based on the receiver’s selection.

Given the OTReceiverSelect message and the two sender inputs, the sender can generate the transfer messages. It does so by deriving two domain separated encryption keys, based on the values S and T generated during initiation and on the masked choice bit sent by the receiver. It then encrypts the left and right inputs under their respective keys and prepares an OTSenderSend message with both ciphertexts. This finishes the OT session for the sender. By the security of the protocol, the receiver will only be able to generate one of the decryption keys, namely that one corresponding to its choice bit.