chore: remove the hash-utils dependency from the KAMT (#2099)

We still need to do this for the HAMT, but this is progress.

ipld/kamt/Cargo.toml

@@ -17,7 +17,6 @@ once_cell = { workspace = true }
 anyhow = { workspace = true }
 fvm_ipld_encoding = { workspace = true }
 fvm_ipld_blockstore = { workspace = true }
-forest_hash_utils = "0.1"
 
 [dev-dependencies]
 hex = { workspace = true }

ipld/kamt/src/id.rs

@@ -2,8 +2,6 @@
 // SPDX-License-Identifier: Apache-2.0, MIT
 use std::borrow::Cow;
 
-use forest_hash_utils::Hash;
-
 use crate::{AsHashedKey, HashedKey};
 
 /// Convenience hasher for docstrings and tests,
@@ -30,7 +28,10 @@ macro_rules! identity_hash {
         $(
             impl AsHashedKey<$t, 32> for Identity {
                 fn as_hashed_key(key: &$t) -> Cow<HashedKey<32>> {
-                    Cow::Owned(IdentityHasher::hash(key))
+                    const BYTES: usize = <$t>::BITS as usize / 8;
+                    let mut output = [0u8; 32];
+                    output[..BYTES].copy_from_slice(&<$t>::to_ne_bytes(*key));
+                    Cow::Owned(output)
                 }
             }
         )*
@@ -39,29 +40,3 @@ macro_rules! identity_hash {
 
 identity_arr!(20, 32, 64);
 identity_hash!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128);
-
-/// Take the first 32 bytes as is.
-#[derive(Default)]
-struct IdentityHasher {
-    bz: HashedKey<32>,
-}
-
-impl IdentityHasher {
-    pub fn hash<K: Hash>(key: K) -> HashedKey<32> {
-        let mut hasher = Self::default();
-        key.hash(&mut hasher);
-        hasher.bz
-    }
-}
-
-impl std::hash::Hasher for IdentityHasher {
-    fn finish(&self) -> u64 {
-        0
-    }
-
-    fn write(&mut self, bytes: &[u8]) {
-        for (i, byte) in bytes.iter().take(self.bz.len()).enumerate() {
-            self.bz[i] = *byte;
-        }
-    }
-}

ipld/kamt/tests/kamt_tests.rs

@@ -6,9 +6,9 @@ use std::collections::{HashMap, HashSet};
 use std::fmt::Display;
 
 use cid::Cid;
-use forest_hash_utils::BytesKey;
 use fvm_ipld_blockstore::{Blockstore, MemoryBlockstore};
 use fvm_ipld_encoding::de::DeserializeOwned;
+use fvm_ipld_encoding::BytesDe;
 use fvm_ipld_encoding::CborStore;
 use fvm_ipld_kamt::id::Identity;
 use fvm_ipld_kamt::{Config, Error, HashedKey, Kamt};
@@ -104,7 +104,7 @@ fn test_load(factory: KamtFactory) {
 
     // loading from an empty store does not work
     let empty_store = MemoryBlockstore::default();
-    assert!(factory.load::<_, u32, BytesKey>(&c2, &empty_store).is_err());
+    assert!(factory.load::<_, u32, BytesDe>(&c2, &empty_store).is_err());
 
     // storing the kamt should produce the same cid as storing the root
     let c3 = kamt.flush().unwrap();
@@ -319,8 +319,8 @@ fn prop_cid_ops_reduced<const N: u32>(factory: KamtFactory, ops: LimitedKeyOps<N
     cid1 == cid2
 }
 
-fn tstring(v: impl Display) -> BytesKey {
-    BytesKey(v.to_string().into_bytes())
+fn tstring(v: impl Display) -> BytesDe {
+    BytesDe(v.to_string().into_bytes())
 }
 
 fn kstring(v: impl Display) -> HashedKey<32> {