fix!: avoid Encryptable domain collisions (tari-project#6275)

Description
---
Updates a few `Encryptable` implementations to make domains canonical.

Closes tari-project#6274.

Motivation and Context
---
As noted in tari-project#6274, concatenation of variable-length data when generating
`Encryptable` domains for AEAD associated data is not canonical for
several types, and could result in collisions.

This PR updates the affected implementations to use fixed-size length
prepending.

How Has This Been Tested?
---
Existing tests.

What process can a PR reviewer use to test or verify this change?
---
Ensure that all `Encryptable` implementations have canonical domain
encodings that cannot collide.

BREAKING CHANGE: Affects the way that local encrypted data is
authenticated, so existing encrypted databases will not function
correctly.

base_layer/key_manager/src/key_manager_service/storage/sqlite_db/key_manager_state.rs

@@ -27,7 +27,7 @@ use chrono::{NaiveDateTime, Utc};
 use diesel::{prelude::*, SqliteConnection};
 use tari_common_sqlite::util::diesel_ext::ExpectedRowsExtension;
 use tari_common_types::encryption::{decrypt_bytes_integral_nonce, encrypt_bytes_integral_nonce};
-use tari_utilities::Hidden;
+use tari_utilities::{ByteArray, Hidden};
 
 use crate::{
     key_manager_service::{
@@ -147,9 +147,15 @@ impl KeyManagerStateSql {
 
 impl Encryptable<XChaCha20Poly1305> for KeyManagerStateSql {
     fn domain(&self, field_name: &'static str) -> Vec<u8> {
-        [Self::KEY_MANAGER, self.branch_seed.as_bytes(), field_name.as_bytes()]
-            .concat()
-            .to_vec()
+        // Because there are two variable-length inputs in the concatenation, we prepend the length of the first
+        [
+            Self::KEY_MANAGER,
+            (self.branch_seed.len() as u64).to_le_bytes().as_bytes(),
+            self.branch_seed.as_bytes(),
+            field_name.as_bytes(),
+        ]
+        .concat()
+        .to_vec()
     }
 
     fn encrypt(mut self, cipher: &XChaCha20Poly1305) -> Result<Self, String> {
@@ -172,9 +178,15 @@ impl Encryptable<XChaCha20Poly1305> for KeyManagerStateSql {
 
 impl Encryptable<XChaCha20Poly1305> for NewKeyManagerStateSql {
     fn domain(&self, field_name: &'static str) -> Vec<u8> {
-        [Self::KEY_MANAGER, self.branch_seed.as_bytes(), field_name.as_bytes()]
-            .concat()
-            .to_vec()
+        // Because there are two variable-length inputs in the concatenation, we prepend the length of the first
+        [
+            Self::KEY_MANAGER,
+            (self.branch_seed.len() as u64).to_le_bytes().as_bytes(),
+            self.branch_seed.as_bytes(),
+            field_name.as_bytes(),
+        ]
+        .concat()
+        .to_vec()
     }
 
     fn encrypt(mut self, cipher: &XChaCha20Poly1305) -> Result<Self, String> {

base_layer/wallet/src/storage/sqlite_db/wallet.rs

@@ -954,9 +954,15 @@ impl ClientKeyValueSql {
 
 impl Encryptable<XChaCha20Poly1305> for ClientKeyValueSql {
     fn domain(&self, field_name: &'static str) -> Vec<u8> {
-        [Self::CLIENT_KEY_VALUE, self.key.as_bytes(), field_name.as_bytes()]
-            .concat()
-            .to_vec()
+        // Because there are two variable-length inputs in the concatenation, we prepend the length of the first
+        [
+            Self::CLIENT_KEY_VALUE,
+            (self.key.len() as u64).to_le_bytes().as_bytes(),
+            self.key.as_bytes(),
+            field_name.as_bytes(),
+        ]
+        .concat()
+        .to_vec()
     }
 
     #[allow(unused_assignments)]