Bandersnatch VRF (#14412)

* Introduce bandersnatch vrf

* Some documentation

* Fix tests

* Fix docs refs

* Some more docs

* Comments about key derivation

* Make clippy happy

* Fix ring context enc/dec test

* Fix docs

* Switch to upstream ring-vrf

* Use sub-domains to construct VrfInput

* Bandersnatch VRF experimental feature

* Restore upstream dep

* Fix feature flags

* Apply typo fix

Co-authored-by: Anton <anton.kalyaev@gmail.com>

* Bump bandersnatch-vrfs

* Weiestrass form has been selected

* Rename bandersnatch testing app crypto id

* Support for seed recovery

* Clarified domain size <-> key size relationship

* cargo fmt

* Trigger CI

* Some required tweaks to crypto types

* Remove leftovers from Cargo.toml

* Remove some TODO notes

* Simplification of structs construction

* Trigger CI

* Apply review suggestion

Co-authored-by: Koute <koute@users.noreply.github.com>

* Docs typo

* Fix keystore tests

* Consistence

* Add ref to git rependency

* Static check of MAX_VRF_IOS value

* Clarify behavior for out of ring keys signatures

* Add test for ring-vrf to the keystore

* Fix docs

---------

Co-authored-by: Anton <anton.kalyaev@gmail.com>
Co-authored-by: Koute <koute@users.noreply.github.com>

substrate/client/keystore/Cargo.toml

@@ -26,9 +26,18 @@ sp-keystore = { version = "0.27.0", path = "../../primitives/keystore" }
 tempfile = "3.1.0"
 
 [features]
-# This feature adds BLS crypto primitives. It should not be used in production since
-# the BLS implementation and interface may still be subject to significant change.
+# This feature adds BLS crypto primitives.
+# It should not be used in production since the implementation and interface may still
+# be subject to significant changes.
 bls-experimental = [
 	"sp-core/bls-experimental",
 	"sp-keystore/bls-experimental",
 ]
+
+# This feature adds Bandersnatch crypto primitives.
+# It should not be used in production since the implementation and interface may still
+# be subject to significant changes.
+bandersnatch-experimental = [
+	"sp-core/bandersnatch-experimental",
+	"sp-keystore/bandersnatch-experimental",
+]

substrate/client/keystore/src/local.rs

@@ -19,6 +19,8 @@
 
 use parking_lot::RwLock;
 use sp_application_crypto::{AppCrypto, AppPair, IsWrappedBy};
+#[cfg(feature = "bandersnatch-experimental")]
+use sp_core::bandersnatch;
 #[cfg(feature = "bls-experimental")]
 use sp_core::{bls377, bls381};
 use sp_core::{
@@ -234,6 +236,69 @@ impl Keystore for LocalKeystore {
 		Ok(sig)
 	}
 
+	#[cfg(feature = "bandersnatch-experimental")]
+	fn bandersnatch_public_keys(&self, key_type: KeyTypeId) -> Vec<bandersnatch::Public> {
+		self.public_keys::<bandersnatch::Pair>(key_type)
+	}
+
+	/// Generate a new pair compatible with the 'bandersnatch' signature scheme.
+	///
+	/// If `[seed]` is `Some` then the key will be ephemeral and stored in memory.
+	#[cfg(feature = "bandersnatch-experimental")]
+	fn bandersnatch_generate_new(
+		&self,
+		key_type: KeyTypeId,
+		seed: Option<&str>,
+	) -> std::result::Result<bandersnatch::Public, TraitError> {
+		self.generate_new::<bandersnatch::Pair>(key_type, seed)
+	}
+
+	#[cfg(feature = "bandersnatch-experimental")]
+	fn bandersnatch_sign(
+		&self,
+		key_type: KeyTypeId,
+		public: &bandersnatch::Public,
+		msg: &[u8],
+	) -> std::result::Result<Option<bandersnatch::Signature>, TraitError> {
+		self.sign::<bandersnatch::Pair>(key_type, public, msg)
+	}
+
+	#[cfg(feature = "bandersnatch-experimental")]
+	fn bandersnatch_vrf_sign(
+		&self,
+		key_type: KeyTypeId,
+		public: &bandersnatch::Public,
+		data: &bandersnatch::vrf::VrfSignData,
+	) -> std::result::Result<Option<bandersnatch::vrf::VrfSignature>, TraitError> {
+		self.vrf_sign::<bandersnatch::Pair>(key_type, public, data)
+	}
+
+	#[cfg(feature = "bandersnatch-experimental")]
+	fn bandersnatch_vrf_output(
+		&self,
+		key_type: KeyTypeId,
+		public: &bandersnatch::Public,
+		input: &bandersnatch::vrf::VrfInput,
+	) -> std::result::Result<Option<bandersnatch::vrf::VrfOutput>, TraitError> {
+		self.vrf_output::<bandersnatch::Pair>(key_type, public, input)
+	}
+
+	#[cfg(feature = "bandersnatch-experimental")]
+	fn bandersnatch_ring_vrf_sign(
+		&self,
+		key_type: KeyTypeId,
+		public: &bandersnatch::Public,
+		data: &bandersnatch::vrf::VrfSignData,
+		prover: &bandersnatch::ring_vrf::RingProver,
+	) -> std::result::Result<Option<bandersnatch::ring_vrf::RingVrfSignature>, TraitError> {
+		let sig = self
+			.0
+			.read()
+			.key_pair_by_type::<bandersnatch::Pair>(public, key_type)?
+			.map(|pair| pair.ring_vrf_sign(data, prover));
+		Ok(sig)
+	}
+
 	#[cfg(feature = "bls-experimental")]
 	fn bls381_public_keys(&self, key_type: KeyTypeId) -> Vec<bls381::Public> {
 		self.public_keys::<bls381::Pair>(key_type)