Support for keyring in runtimes (#2044)

This functionality is required for #1984.

This PR enables
[`sp-keyring`](https://github.com/paritytech/polkadot-sdk/blob/21d36b7b4229c4d5225944f197918cde23fda4ea/substrate/primitives/keyring/src/sr25519.rs#L31-L40)
in `no-std` environments, allowing to generate the public key (e.g.
`AccountKeyring::Alice.public().to_ss58check()`), which can be later
used in the any of built-in [_runtime-genesis-config_
variant](https://github.com/paritytech/polkadot-sdk/blob/21d36b7b4229c4d5225944f197918cde23fda4ea/polkadot/node/service/src/chain_spec.rs#L1066-L1073).


The proposal is as follows:
- expose [`core::Pair`
trait](https://github.com/paritytech/polkadot-sdk/blob/d6f15306282e3de848a09c9aa9cba6f95a7811f0/substrate/primitives/core/src/crypto.rs#L832)
in `no-std`,
- `full_crypto` feature enables `sign` method,
- `std` feature enables `generate_with_phrase` and `generate` methods
(randomness is required),
- All other functionality, currently gated by `full_crypto` will be
available unconditionally (`no-std`):
-- `from_string`
-- `from_string_with_seed`
-- `from seed`
-- `from_seed_slice`
-- `from_phrase`
-- `derive`
-- `verify`

---

Depends on https://github.com/rust-bitcoin/rust-bip39/pull/57

---------

Co-authored-by: command-bot <>
Co-authored-by: Davide Galassi <davxy@datawok.net>

substrate/primitives/application-crypto/src/lib.rs

@@ -20,12 +20,9 @@
 #![warn(missing_docs)]
 #![cfg_attr(not(feature = "std"), no_std)]
 
-pub use sp_core::crypto::{key_types, CryptoTypeId, KeyTypeId};
+pub use sp_core::crypto::{key_types, CryptoTypeId, DeriveJunction, KeyTypeId, Ss58Codec};
 #[doc(hidden)]
-#[cfg(feature = "full_crypto")]
 pub use sp_core::crypto::{DeriveError, Pair, SecretStringError};
-#[cfg(any(feature = "full_crypto", feature = "serde"))]
-pub use sp_core::crypto::{DeriveJunction, Ss58Codec};
 #[doc(hidden)]
 pub use sp_core::{
 	self,
@@ -85,7 +82,7 @@ macro_rules! app_crypto {
 			$module::CRYPTO_ID
 		);
 		$crate::app_crypto_signature_common!($module::Signature, $key_type);
-		$crate::app_crypto_pair!($module::Pair, $key_type, $module::CRYPTO_ID);
+		$crate::app_crypto_pair_common!($module::Pair, $key_type, $module::CRYPTO_ID);
 	};
 }
 
@@ -116,13 +113,15 @@ macro_rules! app_crypto {
 			$module::CRYPTO_ID
 		);
 		$crate::app_crypto_signature_common!($module::Signature, $key_type);
+		$crate::app_crypto_pair_common!($module::Pair, $key_type, $module::CRYPTO_ID);
 	};
 }
 
 /// Declares `Pair` type which is functionally equivalent to `$pair`, but is
 /// new application-specific type whose identifier is `$key_type`.
+/// It is a common part shared between full_crypto and non full_crypto environments.
 #[macro_export]
-macro_rules! app_crypto_pair {
+macro_rules! app_crypto_pair_common {
 	($pair:ty, $key_type:expr, $crypto_type:expr) => {
 		$crate::wrap! {
 			/// A generic `AppPublic` wrapper type over $pair crypto; this has no specific App.
@@ -140,7 +139,14 @@ macro_rules! app_crypto_pair {
 			type Signature = Signature;
 
 			$crate::app_crypto_pair_functions_if_std!($pair);
+			$crate::app_crypto_pair_functions_if_full_crypto!($pair);
 
+			fn from_phrase(
+				phrase: &str,
+				password: Option<&str>,
+			) -> Result<(Self, Self::Seed), $crate::SecretStringError> {
+				<$pair>::from_phrase(phrase, password).map(|r| (Self(r.0), r.1))
+			}
 			fn derive<Iter: Iterator<Item = $crate::DeriveJunction>>(
 				&self,
 				path: Iter,
@@ -154,9 +160,6 @@ macro_rules! app_crypto_pair {
 			fn from_seed_slice(seed: &[u8]) -> Result<Self, $crate::SecretStringError> {
 				<$pair>::from_seed_slice(seed).map(Self)
 			}
-			fn sign(&self, msg: &[u8]) -> Self::Signature {
-				Signature(self.0.sign(msg))
-			}
 			fn verify<M: AsRef<[u8]>>(
 				sig: &Self::Signature,
 				message: M,
@@ -203,13 +206,6 @@ macro_rules! app_crypto_pair_functions_if_std {
 			let r = <$pair>::generate_with_phrase(password);
 			(Self(r.0), r.1, r.2)
 		}
-
-		fn from_phrase(
-			phrase: &str,
-			password: Option<&str>,
-		) -> Result<(Self, Self::Seed), $crate::SecretStringError> {
-			<$pair>::from_phrase(phrase, password).map(|r| (Self(r.0), r.1))
-		}
 	};
 }
 
@@ -220,6 +216,25 @@ macro_rules! app_crypto_pair_functions_if_std {
 	($pair:ty) => {};
 }
 
+/// Implements functions for the `Pair` trait when `feature = "full_crypto"` is enabled.
+#[doc(hidden)]
+#[cfg(feature = "full_crypto")]
+#[macro_export]
+macro_rules! app_crypto_pair_functions_if_full_crypto {
+	($pair:ty) => {
+		fn sign(&self, msg: &[u8]) -> Self::Signature {
+			Signature(self.0.sign(msg))
+		}
+	};
+}
+
+#[doc(hidden)]
+#[cfg(not(feature = "full_crypto"))]
+#[macro_export]
+macro_rules! app_crypto_pair_functions_if_full_crypto {
+	($pair:ty) => {};
+}
+
 /// Declares `Public` type which is functionally equivalent to `$public` but is
 /// new application-specific type whose identifier is `$key_type`.
 /// For full functionality, `app_crypto_public_common!` must be called too.
@@ -267,7 +282,7 @@ macro_rules! app_crypto_public_not_full_crypto {
 		$crate::wrap! {
 			/// A generic `AppPublic` wrapper type over $public crypto; this has no specific App.
 			#[derive(
-				Clone, Eq, PartialEq, Ord, PartialOrd,
+				Clone, Eq, Hash, PartialEq, Ord, PartialOrd,
 				$crate::codec::Encode,
 				$crate::codec::Decode,
 				$crate::RuntimeDebug,
@@ -277,10 +292,13 @@ macro_rules! app_crypto_public_not_full_crypto {
 			pub struct Public($public);
 		}
 
-		impl $crate::CryptoType for Public {}
+		impl $crate::CryptoType for Public {
+			type Pair = Pair;
+		}
 
 		impl $crate::AppCrypto for Public {
 			type Public = Public;
+			type Pair = Pair;
 			type Signature = Signature;
 			const ID: $crate::KeyTypeId = $key_type;
 			const CRYPTO_ID: $crate::CryptoTypeId = $crypto_type;
@@ -452,10 +470,13 @@ macro_rules! app_crypto_signature_not_full_crypto {
 			pub struct Signature($sig);
 		}
 
-		impl $crate::CryptoType for Signature {}
+		impl $crate::CryptoType for Signature {
+			type Pair = Pair;
+		}
 
 		impl $crate::AppCrypto for Signature {
 			type Public = Public;
+			type Pair = Pair;
 			type Signature = Signature;
 			const ID: $crate::KeyTypeId = $key_type;
 			const CRYPTO_ID: $crate::CryptoTypeId = $crypto_type;