From 95d372ba4784171d01f4bdbb9910db2af1a12431 Mon Sep 17 00:00:00 2001
From: threema-donat <129288638+threema-donat@users.noreply.github.com>
Date: Tue, 6 Feb 2024 09:52:58 +0100
Subject: [PATCH] fixup! Add wrapper for Key that implements zeroize

---
 src/crypto.rs | 14 +++++++++++++-
 src/types.rs  |  5 -----
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/crypto.rs b/src/crypto.rs
index ed9fb2597..38b07078f 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -11,6 +11,7 @@ use crypto_secretbox::{
 };
 use data_encoding::{HEXLOWER, HEXLOWER_PERMISSIVE};
 use rand::Rng;
+use serde::{Serialize, Serializer};
 use serde_json as json;
 use zeroize::{Zeroize, ZeroizeOnDrop};
 
@@ -23,6 +24,7 @@ use crate::{
 pub const NONCE_SIZE: usize = 24;
 const KEY_SIZE: usize = 32;
 
+/// Key type used for nacl secretbox cryptography
 #[derive(PartialEq, Zeroize, ZeroizeOnDrop)]
 pub struct Key(SecretboxKey);
 
@@ -56,13 +58,23 @@ impl TryFrom<Vec<u8>> for Key {
     fn try_from(value: Vec<u8>) -> Result<Self, Self::Error> {
         <[u8; KEY_SIZE]>::try_from(value)
             .map_err(|original| {
-                CryptoError::BadKey(format!("Key has wrong size: {}", original.len()))
+                CryptoError::BadKey(format!(
+                    "Key has wrong size: {} instead of {}",
+                    original.len(),
+                    KEY_SIZE
+                ))
             })
             .map(SecretboxKey::from)
             .map(Self::from)
     }
 }
 
+impl Serialize for Key {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        serializer.serialize_str(&HEXLOWER.encode(&self.0))
+    }
+}
+
 fn get_file_nonce() -> &'static Nonce {
     static FILE_NONCE: OnceLock<Nonce> = OnceLock::new();
     FILE_NONCE.get_or_init(|| {
diff --git a/src/types.rs b/src/types.rs
index ab9663e4f..28d4a7dc6 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -83,7 +83,6 @@ pub struct FileMessage {
     thumbnail_media_type: Option<String>,
 
     #[serde(rename = "k")]
-    #[serde(serialize_with = "key_to_hex")]
     blob_encryption_key: Key,
 
     #[serde(rename = "n")]
@@ -392,10 +391,6 @@ impl Serialize for BlobId {
     }
 }
 
-fn key_to_hex<S: Serializer>(val: &Key, serializer: S) -> Result<S::Ok, S::Error> {
-    serializer.serialize_str(&HEXLOWER.encode(&val.as_ref()[..]))
-}
-
 #[cfg(test)]
 mod test {
     use std::collections::HashMap;