feat: initialize Kurdistan SDK - independent fork of Polkadot SDK

substrate/primitives/consensus/sassafras/src/vrf.rs

@@ -0,0 +1,71 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Utilities related to VRF input, pre-output and signatures.
+
+use crate::{Randomness, TicketBody, TicketId};
+#[cfg(not(feature = "std"))]
+use alloc::vec::Vec;
+use codec::Encode;
+use sp_consensus_slots::Slot;
+
+pub use sp_core::bandersnatch::{
+	ring_vrf::{RingProver, RingVerifier, RingVerifierKey, RingVrfSignature},
+	vrf::{VrfInput, VrfPreOutput, VrfSignData, VrfSignature},
+};
+
+/// Ring size (aka authorities count) for Sassafras consensus.
+pub const RING_SIZE: usize = 1024;
+
+/// Bandersnatch VRF [`RingContext`] specialization for Sassafras using [`RING_SIZE`].
+pub type RingContext = sp_core::bandersnatch::ring_vrf::RingContext<RING_SIZE>;
+
+/// Input for slot claim
+pub fn slot_claim_input(randomness: &Randomness, slot: Slot, epoch: u64) -> VrfInput {
+	let v = [b"sassafras-ticket", randomness.as_slice(), &slot.to_le_bytes(), &epoch.to_le_bytes()]
+		.concat();
+	VrfInput::new(&v[..])
+}
+
+/// Signing-data to claim slot ownership during block production.
+pub fn slot_claim_sign_data(randomness: &Randomness, slot: Slot, epoch: u64) -> VrfSignData {
+	let v = [b"sassafras-ticket", randomness.as_slice(), &slot.to_le_bytes(), &epoch.to_le_bytes()]
+		.concat();
+	VrfSignData::new(&v[..], &[])
+}
+
+/// VRF input to generate the ticket id.
+pub fn ticket_id_input(randomness: &Randomness, attempt: u32, epoch: u64) -> VrfInput {
+	let v =
+		[b"sassafras-ticket", randomness.as_slice(), &attempt.to_le_bytes(), &epoch.to_le_bytes()]
+			.concat();
+	VrfInput::new(&v[..])
+}
+
+/// Data to be signed via ring-vrf.
+pub fn ticket_body_sign_data(ticket_body: &TicketBody, ticket_id_input: VrfInput) -> VrfSignData {
+	VrfSignData { vrf_input: ticket_id_input, aux_data: ticket_body.encode() }
+}
+
+/// Make ticket-id from the given VRF pre-output.
+///
+/// Pre-output should have been obtained from the input directly using the vrf
+/// secret key or from the vrf signature pre-output.
+pub fn make_ticket_id(preout: &VrfPreOutput) -> TicketId {
+	let bytes: [u8; 16] = preout.make_bytes()[..16].try_into().unwrap();
+	u128::from_le_bytes(bytes)
+}