Merge rust-bitcoin#2644: Add HKDF to bitcoin_hashes

c9d1ff7 Update hashes API changes (Nick Johnson)
878ab92 Add HMAC Extract-and-Expand Key Derivation Function (Nick Johnson)

Pull request description:

  rustaceanrob and I have been working on a Rust-based BIP324 implementation over at https://github.com/rustaceanrob/bip324. We have been attempting to keep the code pretty clean in hopes of a future "soft landing" in rust-bitcoin. I figured the HKDF implementation is a small, self-contained chunk that might allow us to learn the ropes here first.

  There was a mention in the [discussion thread on BIP324](rust-bitcoin#1691) that the hashes interface may be changing in the near future. I am not sure the effect that would have on this implementation, but happy to work through any issues.

  Closes rust-bitcoin#2551

ACKs for top commit:
  tcharding:
    ACK c9d1ff7
  apoelstra:
    ACK c9d1ff7

Tree-SHA512: 404d51ca055db4366ec57f1503fcf350aebcd181f36a20a17763ea8c47ade851213fc882acd2785313953a3e768d588c230f737ff93f88121b97c34b37c65127

Author: apoelstra

api/hashes/all-features.txt

@@ -66,6 +66,7 @@ impl core::borrow::Borrow<[u8]> for bitcoin_hashes::sha512_256::Hash
 impl core::borrow::Borrow<[u8]> for bitcoin_hashes::siphash24::Hash
 impl core::clone::Clone for bitcoin_hashes::FromSliceError
 impl core::clone::Clone for bitcoin_hashes::hash160::Hash
+impl core::clone::Clone for bitcoin_hashes::hkdf::MaxLengthError
 impl core::clone::Clone for bitcoin_hashes::ripemd160::Hash
 impl core::clone::Clone for bitcoin_hashes::ripemd160::HashEngine
 impl core::clone::Clone for bitcoin_hashes::sha1::Hash
@@ -85,6 +86,7 @@ impl core::clone::Clone for bitcoin_hashes::siphash24::HashEngine
 impl core::clone::Clone for bitcoin_hashes::siphash24::State
 impl core::cmp::Eq for bitcoin_hashes::FromSliceError
 impl core::cmp::Eq for bitcoin_hashes::hash160::Hash
+impl core::cmp::Eq for bitcoin_hashes::hkdf::MaxLengthError
 impl core::cmp::Eq for bitcoin_hashes::ripemd160::Hash
 impl core::cmp::Eq for bitcoin_hashes::sha1::Hash
 impl core::cmp::Eq for bitcoin_hashes::sha256::Hash
@@ -106,6 +108,7 @@ impl core::cmp::Ord for bitcoin_hashes::sha512_256::Hash
 impl core::cmp::Ord for bitcoin_hashes::siphash24::Hash
 impl core::cmp::PartialEq for bitcoin_hashes::FromSliceError
 impl core::cmp::PartialEq for bitcoin_hashes::hash160::Hash
+impl core::cmp::PartialEq for bitcoin_hashes::hkdf::MaxLengthError
 impl core::cmp::PartialEq for bitcoin_hashes::ripemd160::Hash
 impl core::cmp::PartialEq for bitcoin_hashes::sha1::Hash
 impl core::cmp::PartialEq for bitcoin_hashes::sha256::Hash
@@ -153,8 +156,10 @@ impl core::default::Default for bitcoin_hashes::sha512::HashEngine
 impl core::default::Default for bitcoin_hashes::sha512_256::HashEngine
 impl core::default::Default for bitcoin_hashes::siphash24::HashEngine
 impl core::error::Error for bitcoin_hashes::FromSliceError
+impl core::error::Error for bitcoin_hashes::hkdf::MaxLengthError
 impl core::fmt::Debug for bitcoin_hashes::FromSliceError
 impl core::fmt::Debug for bitcoin_hashes::hash160::Hash
+impl core::fmt::Debug for bitcoin_hashes::hkdf::MaxLengthError
 impl core::fmt::Debug for bitcoin_hashes::ripemd160::Hash
 impl core::fmt::Debug for bitcoin_hashes::sha1::Hash
 impl core::fmt::Debug for bitcoin_hashes::sha256::Hash
@@ -168,6 +173,7 @@ impl core::fmt::Debug for bitcoin_hashes::siphash24::HashEngine
 impl core::fmt::Debug for bitcoin_hashes::siphash24::State
 impl core::fmt::Display for bitcoin_hashes::FromSliceError
 impl core::fmt::Display for bitcoin_hashes::hash160::Hash
+impl core::fmt::Display for bitcoin_hashes::hkdf::MaxLengthError
 impl core::fmt::Display for bitcoin_hashes::ripemd160::Hash
 impl core::fmt::Display for bitcoin_hashes::sha1::Hash
 impl core::fmt::Display for bitcoin_hashes::sha256::Hash
@@ -208,6 +214,7 @@ impl core::hash::Hash for bitcoin_hashes::sha512::Hash
 impl core::hash::Hash for bitcoin_hashes::sha512_256::Hash
 impl core::hash::Hash for bitcoin_hashes::siphash24::Hash
 impl core::marker::Copy for bitcoin_hashes::hash160::Hash
+impl core::marker::Copy for bitcoin_hashes::hkdf::MaxLengthError
 impl core::marker::Copy for bitcoin_hashes::ripemd160::Hash
 impl core::marker::Copy for bitcoin_hashes::sha1::Hash
 impl core::marker::Copy for bitcoin_hashes::sha256::Hash
@@ -219,6 +226,7 @@ impl core::marker::Copy for bitcoin_hashes::sha512_256::Hash
 impl core::marker::Copy for bitcoin_hashes::siphash24::Hash
 impl core::marker::Freeze for bitcoin_hashes::FromSliceError
 impl core::marker::Freeze for bitcoin_hashes::hash160::Hash
+impl core::marker::Freeze for bitcoin_hashes::hkdf::MaxLengthError
 impl core::marker::Freeze for bitcoin_hashes::ripemd160::Hash
 impl core::marker::Freeze for bitcoin_hashes::ripemd160::HashEngine
 impl core::marker::Freeze for bitcoin_hashes::sha1::Hash
@@ -238,6 +246,7 @@ impl core::marker::Freeze for bitcoin_hashes::siphash24::HashEngine
 impl core::marker::Freeze for bitcoin_hashes::siphash24::State
 impl core::marker::Send for bitcoin_hashes::FromSliceError
 impl core::marker::Send for bitcoin_hashes::hash160::Hash
+impl core::marker::Send for bitcoin_hashes::hkdf::MaxLengthError
 impl core::marker::Send for bitcoin_hashes::ripemd160::Hash
 impl core::marker::Send for bitcoin_hashes::ripemd160::HashEngine
 impl core::marker::Send for bitcoin_hashes::sha1::Hash
@@ -257,6 +266,7 @@ impl core::marker::Send for bitcoin_hashes::siphash24::HashEngine
 impl core::marker::Send for bitcoin_hashes::siphash24::State
 impl core::marker::StructuralPartialEq for bitcoin_hashes::FromSliceError
 impl core::marker::StructuralPartialEq for bitcoin_hashes::hash160::Hash
+impl core::marker::StructuralPartialEq for bitcoin_hashes::hkdf::MaxLengthError
 impl core::marker::StructuralPartialEq for bitcoin_hashes::ripemd160::Hash
 impl core::marker::StructuralPartialEq for bitcoin_hashes::sha1::Hash
 impl core::marker::StructuralPartialEq for bitcoin_hashes::sha256::Hash
@@ -268,6 +278,7 @@ impl core::marker::StructuralPartialEq for bitcoin_hashes::sha512_256::Hash
 impl core::marker::StructuralPartialEq for bitcoin_hashes::siphash24::Hash
 impl core::marker::Sync for bitcoin_hashes::FromSliceError
 impl core::marker::Sync for bitcoin_hashes::hash160::Hash
+impl core::marker::Sync for bitcoin_hashes::hkdf::MaxLengthError
 impl core::marker::Sync for bitcoin_hashes::ripemd160::Hash
 impl core::marker::Sync for bitcoin_hashes::ripemd160::HashEngine
 impl core::marker::Sync for bitcoin_hashes::sha1::Hash
@@ -287,6 +298,7 @@ impl core::marker::Sync for bitcoin_hashes::siphash24::HashEngine
 impl core::marker::Sync for bitcoin_hashes::siphash24::State
 impl core::marker::Unpin for bitcoin_hashes::FromSliceError
 impl core::marker::Unpin for bitcoin_hashes::hash160::Hash
+impl core::marker::Unpin for bitcoin_hashes::hkdf::MaxLengthError
 impl core::marker::Unpin for bitcoin_hashes::ripemd160::Hash
 impl core::marker::Unpin for bitcoin_hashes::ripemd160::HashEngine
 impl core::marker::Unpin for bitcoin_hashes::sha1::Hash
@@ -306,6 +318,7 @@ impl core::marker::Unpin for bitcoin_hashes::siphash24::HashEngine
 impl core::marker::Unpin for bitcoin_hashes::siphash24::State
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::FromSliceError
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::hash160::Hash
+impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::hkdf::MaxLengthError
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::ripemd160::Hash
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::ripemd160::HashEngine
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::sha1::Hash
@@ -325,6 +338,7 @@ impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::siphash24::Hash
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::siphash24::State
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::FromSliceError
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::hash160::Hash
+impl core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::hkdf::MaxLengthError
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::ripemd160::Hash
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::ripemd160::HashEngine
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::sha1::Hash
@@ -405,6 +419,7 @@ impl<T: bitcoin_hashes::Hash + schemars::JsonSchema> schemars::JsonSchema for bi
 impl<T: bitcoin_hashes::Hash + serde::ser::Serialize> serde::ser::Serialize for bitcoin_hashes::hmac::Hmac<T>
 impl<T: bitcoin_hashes::Hash> bitcoin_hashes::Hash for bitcoin_hashes::hmac::Hmac<T>
 impl<T: bitcoin_hashes::Hash> bitcoin_hashes::HashEngine for bitcoin_hashes::hmac::HmacEngine<T>
+impl<T: bitcoin_hashes::Hash> bitcoin_hashes::hkdf::Hkdf<T>
 impl<T: bitcoin_hashes::Hash> bitcoin_hashes::hmac::HmacEngine<T>
 impl<T: bitcoin_hashes::Hash> bitcoin_io::Write for bitcoin_hashes::hmac::HmacEngine<T>
 impl<T: bitcoin_hashes::Hash> core::convert::AsRef<[u8]> for bitcoin_hashes::hmac::Hmac<T>
@@ -443,26 +458,32 @@ impl<T: core::cmp::PartialEq + bitcoin_hashes::Hash> core::cmp::PartialEq for bi
 impl<T: core::cmp::PartialOrd + bitcoin_hashes::Hash> core::cmp::PartialOrd for bitcoin_hashes::hmac::Hmac<T>
 impl<T: core::hash::Hash + bitcoin_hashes::Hash> core::hash::Hash for bitcoin_hashes::hmac::Hmac<T>
 impl<T: core::marker::Copy + bitcoin_hashes::Hash> core::marker::Copy for bitcoin_hashes::hmac::Hmac<T>
+impl<T> core::marker::Freeze for bitcoin_hashes::hkdf::Hkdf<T> where T: core::marker::Freeze
 impl<T> core::marker::Freeze for bitcoin_hashes::hmac::Hmac<T> where T: core::marker::Freeze
 impl<T> core::marker::Freeze for bitcoin_hashes::hmac::HmacEngine<T> where <T as bitcoin_hashes::Hash>::Engine: core::marker::Freeze
 impl<T> core::marker::Freeze for bitcoin_hashes::hmac::HmacMidState<T> where <<T as bitcoin_hashes::Hash>::Engine as bitcoin_hashes::HashEngine>::MidState: core::marker::Freeze
 impl<T> core::marker::Freeze for bitcoin_hashes::sha256t::Hash<T>
+impl<T> core::marker::Send for bitcoin_hashes::hkdf::Hkdf<T> where T: core::marker::Send
 impl<T> core::marker::Send for bitcoin_hashes::hmac::Hmac<T> where T: core::marker::Send
 impl<T> core::marker::Send for bitcoin_hashes::hmac::HmacEngine<T> where <T as bitcoin_hashes::Hash>::Engine: core::marker::Send
 impl<T> core::marker::Send for bitcoin_hashes::hmac::HmacMidState<T> where <<T as bitcoin_hashes::Hash>::Engine as bitcoin_hashes::HashEngine>::MidState: core::marker::Send
 impl<T> core::marker::Send for bitcoin_hashes::sha256t::Hash<T> where T: core::marker::Send
+impl<T> core::marker::Sync for bitcoin_hashes::hkdf::Hkdf<T> where T: core::marker::Sync
 impl<T> core::marker::Sync for bitcoin_hashes::hmac::Hmac<T> where T: core::marker::Sync
 impl<T> core::marker::Sync for bitcoin_hashes::hmac::HmacEngine<T> where <T as bitcoin_hashes::Hash>::Engine: core::marker::Sync
 impl<T> core::marker::Sync for bitcoin_hashes::hmac::HmacMidState<T> where <<T as bitcoin_hashes::Hash>::Engine as bitcoin_hashes::HashEngine>::MidState: core::marker::Sync
 impl<T> core::marker::Sync for bitcoin_hashes::sha256t::Hash<T> where T: core::marker::Sync
+impl<T> core::marker::Unpin for bitcoin_hashes::hkdf::Hkdf<T> where T: core::marker::Unpin
 impl<T> core::marker::Unpin for bitcoin_hashes::hmac::Hmac<T> where T: core::marker::Unpin
 impl<T> core::marker::Unpin for bitcoin_hashes::hmac::HmacEngine<T> where <T as bitcoin_hashes::Hash>::Engine: core::marker::Unpin
 impl<T> core::marker::Unpin for bitcoin_hashes::hmac::HmacMidState<T> where <<T as bitcoin_hashes::Hash>::Engine as bitcoin_hashes::HashEngine>::MidState: core::marker::Unpin
 impl<T> core::marker::Unpin for bitcoin_hashes::sha256t::Hash<T> where T: core::marker::Unpin
+impl<T> core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::hkdf::Hkdf<T> where T: core::panic::unwind_safe::RefUnwindSafe
 impl<T> core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::hmac::Hmac<T> where T: core::panic::unwind_safe::RefUnwindSafe
 impl<T> core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::hmac::HmacEngine<T> where <T as bitcoin_hashes::Hash>::Engine: core::panic::unwind_safe::RefUnwindSafe
 impl<T> core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::hmac::HmacMidState<T> where <<T as bitcoin_hashes::Hash>::Engine as bitcoin_hashes::HashEngine>::MidState: core::panic::unwind_safe::RefUnwindSafe
 impl<T> core::panic::unwind_safe::RefUnwindSafe for bitcoin_hashes::sha256t::Hash<T> where T: core::panic::unwind_safe::RefUnwindSafe
+impl<T> core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::hkdf::Hkdf<T> where T: core::panic::unwind_safe::UnwindSafe
 impl<T> core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::hmac::Hmac<T> where T: core::panic::unwind_safe::UnwindSafe
 impl<T> core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::hmac::HmacEngine<T> where <T as bitcoin_hashes::Hash>::Engine: core::panic::unwind_safe::UnwindSafe
 impl<T> core::panic::unwind_safe::UnwindSafe for bitcoin_hashes::hmac::HmacMidState<T> where <<T as bitcoin_hashes::Hash>::Engine as bitcoin_hashes::HashEngine>::MidState: core::panic::unwind_safe::UnwindSafe
@@ -563,6 +584,12 @@ pub fn bitcoin_hashes::hash160::Hash::partial_cmp(&self, other: &bitcoin_hashes:
 pub fn bitcoin_hashes::hash160::Hash::schema_name() -> alloc::string::String
 pub fn bitcoin_hashes::hash160::Hash::serialize<S: serde::ser::Serializer>(&self, s: S) -> core::result::Result<<S as serde::ser::Serializer>::Ok, <S as serde::ser::Serializer>::Error>
 pub fn bitcoin_hashes::hash160::Hash::to_byte_array(self) -> Self::Bytes
+pub fn bitcoin_hashes::hkdf::Hkdf<T>::expand(&self, info: &[u8], okm: &mut [u8]) -> core::result::Result<(), bitcoin_hashes::hkdf::MaxLengthError>
+pub fn bitcoin_hashes::hkdf::Hkdf<T>::expand_to_len(&self, info: &[u8], len: usize) -> core::result::Result<alloc::vec::Vec<u8>, bitcoin_hashes::hkdf::MaxLengthError>
+pub fn bitcoin_hashes::hkdf::Hkdf<T>::new(salt: &[u8], ikm: &[u8]) -> Self
+pub fn bitcoin_hashes::hkdf::MaxLengthError::clone(&self) -> bitcoin_hashes::hkdf::MaxLengthError
+pub fn bitcoin_hashes::hkdf::MaxLengthError::eq(&self, other: &bitcoin_hashes::hkdf::MaxLengthError) -> bool
+pub fn bitcoin_hashes::hkdf::MaxLengthError::fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result
 pub fn bitcoin_hashes::hmac::Hmac<T>::all_zeros() -> Self
 pub fn bitcoin_hashes::hmac::Hmac<T>::as_byte_array(&self) -> &Self::Bytes
 pub fn bitcoin_hashes::hmac::Hmac<T>::as_ref(&self) -> &[u8]
@@ -914,6 +941,7 @@ pub macro bitcoin_hashes::sha256t_hash_newtype!
 pub mod bitcoin_hashes
 pub mod bitcoin_hashes::cmp
 pub mod bitcoin_hashes::hash160
+pub mod bitcoin_hashes::hkdf
 pub mod bitcoin_hashes::hmac
 pub mod bitcoin_hashes::ripemd160
 pub mod bitcoin_hashes::serde_macros
@@ -928,6 +956,8 @@ pub mod bitcoin_hashes::sha512_256
 pub mod bitcoin_hashes::siphash24
 pub struct bitcoin_hashes::FromSliceError
 pub struct bitcoin_hashes::HmacEngine<T: bitcoin_hashes::Hash>
+pub struct bitcoin_hashes::hkdf::Hkdf<T: bitcoin_hashes::Hash>
+pub struct bitcoin_hashes::hkdf::MaxLengthError
 pub struct bitcoin_hashes::hmac::HmacEngine<T: bitcoin_hashes::Hash>
 pub struct bitcoin_hashes::hmac::HmacMidState<T: bitcoin_hashes::Hash>
 pub struct bitcoin_hashes::ripemd160::HashEngine