lssa/wallet/src/token_transfers/deshielded.rs

use common::{ExecutionFailureKind, sequencer_client::json::SendTxResponse};
use k256::elliptic_curve::rand_core::{OsRng, RngCore};
use key_protocol::key_management::ephemeral_key_holder::EphemeralKeyHolder;
use nssa::Address;
use nssa_core::{SharedSecretKey, encryption::EphemeralPublicKey};

use crate::WalletCore;

impl WalletCore {
    pub async fn send_deshielded_native_token_transfer(
        &self,
        from: Address,
        to: Address,
        balance_to_move: u128,
    ) -> Result<(SendTxResponse, nssa_core::SharedSecretKey), ExecutionFailureKind> {
        let Some((from_keys, mut from_acc)) =
            self.storage.user_data.get_private_account(&from).cloned()
        else {
            return Err(ExecutionFailureKind::KeyNotFoundError);
        };

        let Ok(to_acc) = self.get_account(to).await else {
            return Err(ExecutionFailureKind::KeyNotFoundError);
        };

        if from_acc.balance >= balance_to_move {
            let program = nssa::program::Program::authenticated_transfer_program();

            let npk_from = from_keys.nullifer_public_key;
            let ipk_from = from_keys.incoming_viewing_public_key;

            let sender_commitment = nssa_core::Commitment::new(&npk_from, &from_acc);

            let sender_pre =
                nssa_core::account::AccountWithMetadata::new(from_acc.clone(), true, &npk_from);
            let recipient_pre = nssa_core::account::AccountWithMetadata {
                account: to_acc.clone(),
                is_authorized: false,
                account_id: to,
            };

            let eph_holder = EphemeralKeyHolder::new(&npk_from);
            let shared_secret = eph_holder.calculate_shared_secret_sender(&ipk_from);

            let (output, proof) = nssa::privacy_preserving_transaction::circuit::execute_and_prove(
                &[sender_pre, recipient_pre],
                &nssa::program::Program::serialize_instruction(balance_to_move).unwrap(),
                &[1, 0],
                &[from_acc.nonce + 1],
                &[(npk_from.clone(), shared_secret.clone())],
                &[(
                    from_keys.private_key_holder.nullifier_secret_key,
                    self.sequencer_client
                        .get_proof_for_commitment(sender_commitment)
                        .await
                        .unwrap()
                        .unwrap(),
                )],
                &program,
            )
            .unwrap();

            let message =
                nssa::privacy_preserving_transaction::message::Message::try_from_circuit_output(
                    vec![to],
                    vec![],
                    vec![(
                        npk_from.clone(),
                        ipk_from.clone(),
                        eph_holder.generate_ephemeral_public_key(),
                    )],
                    output,
                )
                .unwrap();

            let witness_set =
                nssa::privacy_preserving_transaction::witness_set::WitnessSet::for_message(
                    &message,
                    proof,
                    &[],
                );

            let tx = nssa::privacy_preserving_transaction::PrivacyPreservingTransaction::new(
                message,
                witness_set,
            );

            Ok((
                self.sequencer_client.send_tx_private(tx).await?,
                shared_secret,
            ))
        } else {
            Err(ExecutionFailureKind::InsufficientFundsError)
        }
    }
}