Use ic_representation_independent_hash instead of a copied hash code (#…

…2379)

* Use ic_representation_independent_hash instead of a copied hash code

* Update Cargo.lock

src/canister_sig_util/Cargo.toml

@@ -9,6 +9,7 @@ edition = "2021"
 candid.workspace = true
 ic-cdk.workspace = true
 ic-certification.workspace = true
+ic-representation-independent-hash = "2.5"
 
 # other dependencies
 hex.workspace = true

src/canister_sig_util/src/lib.rs

@@ -1,10 +1,10 @@
 use candid::Principal;
 use ic_certification::{Hash, HashTree};
+use ic_representation_independent_hash::{representation_independent_hash, Value};
 use lazy_static::lazy_static;
 use serde::Serialize;
 use serde_bytes::ByteBuf;
 use sha2::{Digest, Sha256};
-use std::collections::HashMap;
 
 pub mod signature_map;
 
@@ -141,128 +141,27 @@ pub fn delegation_signature_msg(
     expiration: u64,
     targets: Option<&Vec<Vec<u8>>>,
 ) -> Vec<u8> {
-    use hash::Value;
-
-    let mut m = HashMap::new();
-    m.insert("pubkey", Value::Bytes(pubkey));
-    m.insert("expiration", Value::U64(expiration));
+    let mut m: Vec<(String, Value)> = vec![];
+    m.push(("pubkey".into(), Value::Bytes(pubkey.to_vec())));
+    m.push(("expiration".into(), Value::Number(expiration)));
     if let Some(targets) = targets.as_ref() {
         let mut arr = Vec::with_capacity(targets.len());
         for t in targets.iter() {
-            arr.push(Value::Bytes(t.as_ref()));
+            arr.push(Value::Bytes(t.to_vec()));
         }
-        m.insert("targets", Value::Array(arr));
+        m.push(("targets".into(), Value::Array(arr)));
     }
-    let map_hash = hash::hash_of_map(m);
+    let map_hash = representation_independent_hash(m.as_slice());
     msg_with_domain(b"ic-request-auth-delegation", &map_hash)
 }
 
-pub fn msg_with_domain(sep: &[u8], bytes: &[u8]) -> Vec<u8> {
+fn msg_with_domain(sep: &[u8], bytes: &[u8]) -> Vec<u8> {
     let mut msg = vec![sep.len() as u8];
     msg.append(&mut sep.to_vec());
     msg.append(&mut bytes.to_vec());
     msg
 }
 
-// This is a copy or II's hash.rs, to avoid dependency on II's code.
-// TODO: remove the copy and use ic_representation_independent_hash-crate
-//       once ic_representation_independent_hash::Value supports Array-values.
-mod hash {
-    use ic_certification::Hash;
-    use serde::{Deserialize, Serialize};
-    use sha2::{Digest, Sha256};
-    use std::collections::HashMap;
-    use std::convert::AsRef;
-
-    #[derive(Clone, Serialize, Deserialize)]
-    pub enum Value<'a> {
-        Bytes(#[serde(with = "serde_bytes")] &'a [u8]),
-        String(&'a str),
-        U64(u64),
-        Array(Vec<Value<'a>>),
-    }
-
-    pub fn hash_of_map<S: AsRef<str>>(map: HashMap<S, Value>) -> Hash {
-        let mut hashes: Vec<Vec<u8>> = Vec::new();
-        for (key, val) in map.into_iter() {
-            hashes.push(hash_key_val(key.as_ref(), val));
-        }
-
-        // Computes hash by first sorting by "field name" hash, which is the
-        // same as sorting by concatenation of H(field name) · H(field value)
-        // (although in practice it's actually more stable in the presence of
-        // duplicated field names). Then concatenate all the hashes.
-        hashes.sort();
-
-        let mut hasher = Sha256::new();
-        for hash in hashes {
-            hasher.update(&hash);
-        }
-
-        hasher.finalize().into()
-    }
-
-    fn hash_key_val(key: &str, val: Value<'_>) -> Vec<u8> {
-        let mut key_hash = hash_string(key).to_vec();
-        let val_hash = hash_val(val);
-        key_hash.extend_from_slice(&val_hash[..]);
-        key_hash
-    }
-
-    pub fn hash_string(value: &str) -> Hash {
-        hash_bytes(value.as_bytes())
-    }
-
-    pub fn hash_bytes(value: impl AsRef<[u8]>) -> Hash {
-        let mut hasher = Sha256::new();
-        hasher.update(value.as_ref());
-        hasher.finalize().into()
-    }
-
-    fn hash_u64(value: u64) -> Hash {
-        // We need at most ⌈ 64 / 7 ⌉ = 10 bytes to encode a 64 bit
-        // integer in LEB128.
-        let mut buf = [0u8; 10];
-        let mut n = value;
-        let mut i = 0;
-
-        loop {
-            let byte = (n & 0x7f) as u8;
-            n >>= 7;
-
-            if n == 0 {
-                buf[i] = byte;
-                break;
-            } else {
-                buf[i] = byte | 0x80;
-                i += 1;
-            }
-        }
-
-        hash_bytes(&buf[..=i])
-    }
-
-    // Arrays encoded as the concatenation of the hashes of the encodings of the
-    // array elements.
-    fn hash_array(elements: Vec<Value<'_>>) -> Hash {
-        let mut hasher = Sha256::new();
-        elements
-            .into_iter()
-            // Hash the encoding of all the array elements.
-            .for_each(|e| hasher.update(&hash_val(e)[..]));
-        hasher.finalize().into() // hash the concatenation of the hashes.
-    }
-
-    fn hash_val(val: Value<'_>) -> Hash {
-        match val {
-            Value::String(string) => hash_string(string),
-            Value::Bytes(bytes) => hash_bytes(bytes),
-            Value::U64(integer) => hash_u64(integer),
-            Value::Array(elements) => hash_array(elements),
-        }
-    }
-}
-
 #[derive(Serialize)]
 struct CanisterSig {
     certificate: ByteBuf,