Rename XpubIdentifier to XKeyIdentifier

The BIP-32 extended key identifier is used to identify xpubs and xprivs,
we can rename it to show this.

bitcoin/src/bip32.rs

@@ -6,6 +6,8 @@
 //! at <https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki>.
 //!
 
+#![allow(deprecated)] // Remove once we remove XpubIdentifier.
+
 use core::convert::TryInto;
 use core::default::Default;
 use core::ops::Index;
@@ -54,7 +56,11 @@ impl_bytes_newtype!(Fingerprint, 4);
 
 hash_newtype! {
     /// XpubIdentifier as defined in BIP-32.
+    #[deprecated(since = "0.0.0-NEXT-RELEASE", note = "use XKeyIdentifier instead")]
     pub struct XpubIdentifier(hash160::Hash);
+
+    /// Extended key identifier as defined in BIP-32.
+    pub struct XKeyIdentifier(hash160::Hash);
 }
 
 /// Extended private key
@@ -676,7 +682,7 @@ impl Xpriv {
     }
 
     /// Returns the HASH160 of the public key belonging to the xpriv
-    pub fn identifier<C: secp256k1::Signing>(&self, secp: &Secp256k1<C>) -> XpubIdentifier {
+    pub fn identifier<C: secp256k1::Signing>(&self, secp: &Secp256k1<C>) -> XKeyIdentifier {
         Xpub::from_priv(secp, self).identifier()
     }
 
@@ -807,10 +813,10 @@ impl Xpub {
     }
 
     /// Returns the HASH160 of the chaincode
-    pub fn identifier(&self) -> XpubIdentifier {
-        let mut engine = XpubIdentifier::engine();
+    pub fn identifier(&self) -> XKeyIdentifier {
+        let mut engine = XKeyIdentifier::engine();
         engine.write_all(&self.public_key.serialize()).expect("engines don't error");
-        XpubIdentifier::from_engine(engine)
+        XKeyIdentifier::from_engine(engine)
     }
 
     /// Returns the first four bytes of the identifier
@@ -859,12 +865,12 @@ impl FromStr for Xpub {
     }
 }
 
-impl From<Xpub> for XpubIdentifier {
-    fn from(key: Xpub) -> XpubIdentifier { key.identifier() }
+impl From<Xpub> for XKeyIdentifier {
+    fn from(key: Xpub) -> XKeyIdentifier { key.identifier() }
 }
 
-impl From<&Xpub> for XpubIdentifier {
-    fn from(key: &Xpub) -> XpubIdentifier { key.identifier() }
+impl From<&Xpub> for XKeyIdentifier {
+    fn from(key: &Xpub) -> XKeyIdentifier { key.identifier() }
 }
 
 #[cfg(test)]

bitcoin/src/lib.rs

@@ -129,7 +129,7 @@ use core2::io;
 
 pub use crate::address::{Address, AddressType};
 pub use crate::amount::{Amount, Denomination, SignedAmount};
-pub use crate::bip32::XpubIdentifier;
+pub use crate::bip32::XKeyIdentifier;
 pub use crate::blockdata::block::{self, Block};
 pub use crate::blockdata::fee_rate::FeeRate;
 pub use crate::blockdata::locktime::{self, absolute, relative};