ark-lib 0.1.3

pub extern crate bitcoin;

#[macro_use] extern crate serde;
#[macro_use] extern crate lazy_static;

#[macro_use] pub mod util;

pub mod address;
pub mod arkoor;
pub mod attestations;
pub mod board;
pub mod connectors;
pub mod encode;
pub mod error;
pub mod fees;
pub mod forfeit;
pub mod lightning;
pub mod mailbox;
pub mod musig;
pub mod offboard;
pub mod rounds;
pub mod time;
pub mod tree;
pub mod vtxo;
pub mod integration;

pub use crate::address::Address;
pub use crate::encode::{ProtocolEncoding, WriteExt, ReadExt, ProtocolDecodingError};
pub use crate::vtxo::{Vtxo, VtxoId, VtxoPolicy, ServerVtxoPolicy, ServerVtxo};

#[cfg(test)]
mod napkin;
#[cfg(any(test, feature = "test-util"))]
pub mod test_util;


use std::time::Duration;

use bitcoin::{Amount, FeeRate, Network};
use bitcoin::secp256k1::{self, PublicKey};

use bitcoin_ext::BlockDelta;

use crate::fees::FeeSchedule;

lazy_static! {
	/// Global secp context.
	pub static ref SECP: secp256k1::Secp256k1<secp256k1::All> = secp256k1::Secp256k1::new();
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ArkInfo {
	/// The bitcoin network the server operates on
	pub network: Network,
	/// The Ark server pubkey
	pub server_pubkey: PublicKey,
	/// The pubkey used for blinding unified mailbox IDs
	pub mailbox_pubkey: PublicKey,
	/// The interval between each round
	pub round_interval: Duration,
	/// Number of nonces per round
	pub nb_round_nonces: usize,
	/// Delta between exit confirmation and coins becoming spendable
	pub vtxo_exit_delta: BlockDelta,
	/// Expiration delta of the VTXO
	pub vtxo_expiry_delta: BlockDelta,
	/// The number of blocks after which an HTLC-send VTXO expires once granted.
	pub htlc_send_expiry_delta: BlockDelta,
	/// The number of blocks to keep between Lightning and Ark HTLCs expiries
	pub htlc_expiry_delta: BlockDelta,
	/// Maximum amount of a VTXO
	pub max_vtxo_amount: Option<Amount>,
	/// The number of confirmations required to register a board vtxo
	pub required_board_confirmations: usize,
	/// Maximum CLTV delta server will allow clients to request an
	/// invoice generation with.
	pub max_user_invoice_cltv_delta: u16,
	/// Minimum amount for a board the server will cosign
	pub min_board_amount: Amount,

	//TODO(stevenroose) move elsewhere eith other temp fields

	/// The feerate for offboards
	pub offboard_feerate: FeeRate,

	/// Indicates whether the Ark server requires clients to either
	/// provide a VTXO ownership proof, or a lightning receive token
	/// when preparing a lightning claim.
	pub ln_receive_anti_dos_required: bool,

	/// Fee schedule for all Ark operations
	pub fees: FeeSchedule,

	/// Maximum exit depth (genesis chain length) allowed for a VTXO.
	/// Once a VTXO's exit depth reaches this value the server will refuse to
	/// cosign further OOR transactions spending it. Clients should refresh
	/// their VTXOs into a round before this limit is reached.
	pub max_vtxo_exit_depth: u16,
}

/// Request for the creation of an vtxo.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Deserialize, Serialize)]
pub struct VtxoRequest {
	pub amount: Amount,
	#[serde(with = "crate::encode::serde")]
	pub policy: VtxoPolicy,
}

impl AsRef<VtxoRequest> for VtxoRequest {
	fn as_ref(&self) -> &VtxoRequest {
	    self
	}
}

/// Request for the creation of an vtxo in a signed round
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Deserialize, Serialize)]
pub struct SignedVtxoRequest {
	/// The actual VTXO request.
	pub vtxo: VtxoRequest,
	/// The public key used by the client to cosign the transaction tree
	/// The client SHOULD forget this key after signing it
	pub cosign_pubkey: PublicKey,
	/// The public cosign nonces for the cosign pubkey
	pub nonces: Vec<musig::PublicNonce>,
}

impl AsRef<VtxoRequest> for SignedVtxoRequest {
	fn as_ref(&self) -> &VtxoRequest {
	    &self.vtxo
	}
}

pub mod scripts {
	use bitcoin::{opcodes, ScriptBuf, TapSighash, TapTweakHash, Transaction};
	use bitcoin::hashes::{sha256, ripemd160, Hash};
	use bitcoin::secp256k1::{schnorr, PublicKey, XOnlyPublicKey};

	use bitcoin_ext::{BlockDelta, BlockHeight, TAPROOT_KEYSPEND_WEIGHT};

	use crate::musig;

	/// Create a tapscript that is a checksig and a relative timelock.
	pub fn delayed_sign(delay_blocks: BlockDelta, pubkey: XOnlyPublicKey) -> ScriptBuf {
		let csv = bitcoin::Sequence::from_height(delay_blocks);
		bitcoin::Script::builder()
			.push_int(csv.to_consensus_u32() as i64)
			.push_opcode(opcodes::all::OP_CSV)
			.push_opcode(opcodes::all::OP_DROP)
			.push_x_only_key(&pubkey)
			.push_opcode(opcodes::all::OP_CHECKSIG)
			.into_script()
	}

	/// Create a tapscript that is a checksig and an absolute timelock.
	pub fn timelock_sign(timelock_height: BlockHeight, pubkey: XOnlyPublicKey) -> ScriptBuf {
		let lt = bitcoin::absolute::LockTime::from_height(timelock_height).unwrap();
		bitcoin::Script::builder()
			.push_int(lt.to_consensus_u32() as i64)
			.push_opcode(opcodes::all::OP_CLTV)
			.push_opcode(opcodes::all::OP_DROP)
			.push_x_only_key(&pubkey)
			.push_opcode(opcodes::all::OP_CHECKSIG)
			.into_script()
	}

	/// Create a tapscript
	pub fn delay_timelock_sign(
		delay_blocks: BlockDelta,
		timelock_height: BlockHeight,
		pubkey: XOnlyPublicKey,
	) -> ScriptBuf {
		let csv = bitcoin::Sequence::from_height(delay_blocks);
		let lt = bitcoin::absolute::LockTime::from_height(timelock_height).unwrap();
		bitcoin::Script::builder()
			.push_int(lt.to_consensus_u32().try_into().unwrap())
			.push_opcode(opcodes::all::OP_CLTV)
			.push_opcode(opcodes::all::OP_DROP)
			.push_int(csv.to_consensus_u32().try_into().unwrap())
			.push_opcode(opcodes::all::OP_CSV)
			.push_opcode(opcodes::all::OP_DROP)
			.push_x_only_key(&pubkey)
			.push_opcode(opcodes::all::OP_CHECKSIG)
			.into_script()
	}

	/// Contract that requires revealing the preimage to the given hash
	/// and a signature using the given (aggregate) pubkey
	///
	/// The expected spending script witness is the preimage followed by
	/// the signature.
	pub fn hash_and_sign(hash: sha256::Hash, pubkey: XOnlyPublicKey) -> ScriptBuf {
		let hash_160 = ripemd160::Hash::hash(&hash[..]);

		bitcoin::Script::builder()
			.push_opcode(opcodes::all::OP_HASH160)
			.push_slice(hash_160.as_byte_array())
			.push_opcode(opcodes::all::OP_EQUALVERIFY)
			.push_x_only_key(&pubkey)
			.push_opcode(opcodes::all::OP_CHECKSIG)
			.into_script()
	}

	pub fn hash_delay_sign(
		hash: sha256::Hash,
		delay_blocks: BlockDelta,
		pubkey: XOnlyPublicKey,
	) -> ScriptBuf {
		let hash_160 = ripemd160::Hash::hash(&hash[..]);
		let csv = bitcoin::Sequence::from_height(delay_blocks);

		bitcoin::Script::builder()
			.push_int(csv.to_consensus_u32().try_into().unwrap())
			.push_opcode(opcodes::all::OP_CSV)
			.push_opcode(opcodes::all::OP_DROP)
			.push_opcode(opcodes::all::OP_HASH160)
			.push_slice(hash_160.as_byte_array())
			.push_opcode(opcodes::all::OP_EQUALVERIFY)
			.push_x_only_key(&pubkey)
			.push_opcode(opcodes::all::OP_CHECKSIG)
			.into_script()
	}

	/// Fill in the signatures into the unsigned transaction.
	///
	/// Panics if the nb of inputs and signatures doesn't match or if some input
	/// witnesses are not empty.
	pub fn fill_taproot_sigs(tx: &mut Transaction, sigs: &[schnorr::Signature]) {
		assert_eq!(tx.input.len(), sigs.len());
		for (input, sig) in tx.input.iter_mut().zip(sigs.iter()) {
			assert!(input.witness.is_empty());
			input.witness.push(&sig[..]);
			debug_assert_eq!(TAPROOT_KEYSPEND_WEIGHT, input.witness.size());
		}
	}

	/// Verify a partial signature from either of the two parties cosigning a tx.
	pub fn verify_partial_sig(
		sighash: TapSighash,
		tweak: TapTweakHash,
		signer: (PublicKey, &musig::PublicNonce),
		other: (PublicKey, &musig::PublicNonce),
		partial_signature: &musig::PartialSignature,
	) -> bool {
		let agg_nonce = musig::nonce_agg(&[&signer.1, &other.1]);
		let agg_pk = musig::tweaked_key_agg([signer.0, other.0], tweak.to_byte_array()).0;

		let session = musig::Session::new(&agg_pk, agg_nonce, &sighash.to_byte_array());
		session.partial_verify(
			&agg_pk, partial_signature, signer.1, musig::pubkey_to(signer.0),
		)
	}
}