Babe VRF Signing in keystore (#6225)

* Introduce trait

* Implement VRFSigner in keystore

* Use vrf_sign from keystore

* Convert output to VRFInOut

* Simplify conversion

* vrf_sign secondary slot using keystore

* Fix RPC call to claim_slot

* Use Public instead of Pair

* Check primary threshold in signer

* Fix interface to return error

* Move vrf_sign to BareCryptoStore

* Fix authorship_works test

* Fix BABE logic leaks

* Acquire a read lock once

* Also fix RPC acquiring the read lock once

* Implement a generic way to construct VRF Transcript

* Use make_transcript_data to call sr25519_vrf_sign

* Make sure VRFTranscriptData is serializable

* Cleanup

* Move VRF to it's own module

* Implement & test VRF signing in testing module

* Remove leftover

* Fix feature requirements

* Revert removing vec macro

* Drop keystore pointer to prevent deadlock

* Nitpicks

* Add test to make sure make_transcript works

* Fix mismatch in VRF transcript

* Add a test to verify transcripts match in babe

* Return VRFOutput and VRFProof from keystore

substrate/client/consensus/babe/src/tests.rs

@@ -21,8 +21,14 @@
 #![allow(deprecated)]
 use super::*;
 use authorship::claim_slot;
-use sp_core::crypto::Pair;
-use sp_consensus_babe::{AuthorityPair, SlotNumber, AllowedSlots};
+use sp_core::{crypto::Pair, vrf::make_transcript as transcript_from_data};
+use sp_consensus_babe::{
+	AuthorityPair,
+	SlotNumber,
+	AllowedSlots,
+	make_transcript,
+	make_transcript_data,
+};
 use sc_block_builder::{BlockBuilder, BlockBuilderProvider};
 use sp_consensus::{
 	NoNetwork as DummyOracle, Proposal, RecordProof,
@@ -35,6 +41,11 @@ use sp_runtime::{generic::DigestItem, traits::{Block as BlockT, DigestFor}};
 use sc_client_api::{BlockchainEvents, backend::TransactionFor};
 use log::debug;
 use std::{time::Duration, cell::RefCell, task::Poll};
+use rand::RngCore;
+use rand_chacha::{
+	rand_core::SeedableRng,
+	ChaChaRng,
+};
 
 type Item = DigestItem<Hash>;
 
@@ -796,3 +807,36 @@ fn verify_slots_are_strictly_increasing() {
 		&mut block_import,
 	);
 }
+
+#[test]
+fn babe_transcript_generation_match() {
+	let _ = env_logger::try_init();
+	let keystore_path = tempfile::tempdir().expect("Creates keystore path");
+	let keystore = sc_keystore::Store::open(keystore_path.path(), None).expect("Creates keystore");
+	let pair = keystore.write().insert_ephemeral_from_seed::<AuthorityPair>("//Alice")
+		.expect("Generates authority pair");
+
+	let epoch = Epoch {
+		start_slot: 0,
+		authorities: vec![(pair.public(), 1)],
+		randomness: [0; 32],
+		epoch_index: 1,
+		duration: 100,
+		config: BabeEpochConfiguration {
+			c: (3, 10),
+			allowed_slots: AllowedSlots::PrimaryAndSecondaryPlainSlots,
+		},
+	};
+
+	let orig_transcript = make_transcript(&epoch.randomness.clone(), 1, epoch.epoch_index);
+	let new_transcript = make_transcript_data(&epoch.randomness, 1, epoch.epoch_index);
+
+	let test = |t: merlin::Transcript| -> [u8; 16] {
+		let mut b = [0u8; 16];
+		t.build_rng()
+			.finalize(&mut ChaChaRng::from_seed([0u8;32]))
+			.fill_bytes(&mut b);
+		b
+	};
+	debug_assert!(test(orig_transcript) == test(transcript_from_data(new_transcript)));
+}