Restrict Protected to some heap types. (#6471)

* Restrict `Protected` to some heap types.

* Comment abut Protected usage.

* Remove Protected from crypto, use secrecy crate for existing uses.

* use a parse function

* fix error convert

* Rename and move secretY string function.

* std result

substrate/primitives/core/src/crypto.rs

@@ -37,10 +37,16 @@ use regex::Regex;
 use base58::{FromBase58, ToBase58};
 #[cfg(feature = "std")]
 use crate::hexdisplay::HexDisplay;
-use zeroize::Zeroize;
 #[doc(hidden)]
 pub use sp_std::ops::Deref;
 use sp_runtime_interface::pass_by::PassByInner;
+/// Trait to zeroize a memory buffer.
+pub use zeroize::Zeroize;
+/// Trait for accessing reference to `SecretString`.
+pub use secrecy::ExposeSecret;
+/// A store for sensitive data.
+#[cfg(feature = "std")]
+pub use secrecy::SecretString;
 
 /// The root phrase for our publicly known keys.
 pub const DEV_PHRASE: &str = "bottom drive obey lake curtain smoke basket hold race lonely fit walk";
@@ -79,51 +85,6 @@ impl<S, T: UncheckedFrom<S>> UncheckedInto<T> for S {
 	}
 }
 
-/// A store for sensitive data.
-///
-/// Calls `Zeroize::zeroize` upon `Drop`.
-#[derive(Clone)]
-pub struct Protected<T: Zeroize>(T);
-
-impl<T: Zeroize> AsRef<T> for Protected<T> {
-	fn as_ref(&self) -> &T {
-		&self.0
-	}
-}
-
-impl<T: Zeroize> sp_std::ops::Deref for Protected<T> {
-	type Target = T;
-
-	fn deref(&self) -> &T {
-		&self.0
-	}
-}
-
-#[cfg(feature = "std")]
-impl<T: Zeroize> std::fmt::Debug for Protected<T> {
-	fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
-		write!(fmt, "<protected>")
-	}
-}
-
-impl<T: Zeroize> From<T> for Protected<T> {
-	fn from(t: T) -> Self {
-		Protected(t)
-	}
-}
-
-impl<T: Zeroize> Zeroize for Protected<T> {
-	fn zeroize(&mut self) {
-		self.0.zeroize()
-	}
-}
-
-impl<T: Zeroize> Drop for Protected<T> {
-	fn drop(&mut self) {
-		self.zeroize()
-	}
-}
-
 /// An error with the interpretation of a secret.
 #[derive(Debug, Clone, PartialEq, Eq)]
 #[cfg(feature = "full_crypto")]