AAD: fix serialization and deserialization logic

In previous commits we did a duplicated base64 encoding and decoding
when serializing/deserializing the AAD field.

Signed-off-by: Xynnn007 <xynnn@linux.alibaba.com>

src/lib.rs

@@ -157,7 +157,7 @@ where
     Ok(decoded)
 }
 
-fn serialize_base64_option<S>(
+fn serialize_base64_vec<S>(
     sub: &Option<Vec<u8>>,
     serializer: S,
 ) -> core::result::Result<S::Ok, S::Error>
@@ -166,25 +166,23 @@ where
 {
     match sub {
         Some(value) => {
-            let encoded = BASE64_URL_SAFE_NO_PAD.encode(value);
+            let encoded = String::from_utf8(value.clone()).map_err(serde::ser::Error::custom)?;
             serializer.serialize_str(&encoded)
         }
         None => serializer.serialize_none(),
     }
 }
 
-fn deserialize_base64_option<'de, D>(
+fn deserialize_base64_vec<'de, D>(
     deserializer: D,
 ) -> core::result::Result<Option<Vec<u8>>, D::Error>
 where
     D: serde::Deserializer<'de>,
 {
-    let encoded = String::deserialize(deserializer)?;
-    let decoded = BASE64_URL_SAFE_NO_PAD
-        .decode(encoded)
-        .map_err(serde::de::Error::custom)?;
+    let string = String::deserialize(deserializer)?;
+    let bytes = string.into_bytes();
 
-    Ok(Some(decoded))
+    Ok(Some(bytes))
 }
 
 #[derive(Clone, Serialize, Deserialize, Debug)]
@@ -202,10 +200,10 @@ pub struct Response {
     pub encrypted_key: Vec<u8>,
 
     #[serde(
-        deserialize_with = "deserialize_base64_option",
         skip_serializing_if = "Option::is_none",
-        serialize_with = "serialize_base64_option",
-        default = "Option::default"
+        default = "Option::default",
+        serialize_with = "serialize_base64_vec",
+        deserialize_with = "deserialize_base64_vec"
     )]
     pub aad: Option<Vec<u8>>,
 
@@ -320,7 +318,7 @@ mod tests {
             "protected": "eyJhbGciOiJmYWtlYWxnIiwiZW5jIjoiZmFrZWVuYyJ9Cg",
             "encrypted_key": "ZmFrZWtleQ",
             "iv": "cmFuZG9tZGF0YQ",
-            "aad": "ZmFrZWFhZA",
+            "aad": "fakeaad",
             "ciphertext": "ZmFrZWVuY291dHB1dA",
             "tag": "ZmFrZXRhZw"
         }"#;
@@ -344,7 +342,7 @@ mod tests {
             "protected": "eyJhbGciOiJmYWtlYWxnIiwiZW5jIjoiZmFrZWVuYyIsImZha2VmaWVsZCI6ImZha2V2YWx1ZSJ9",
             "encrypted_key": "ZmFrZWtleQ",
             "iv": "cmFuZG9tZGF0YQ",
-            "aad": "ZmFrZWFhZA",
+            "aad": "fakeaad",
             "ciphertext": "ZmFrZWVuY291dHB1dA",
             "tag": "ZmFrZXRhZw"
         }"#;
@@ -382,7 +380,7 @@ mod tests {
             "protected": "eyJhbGciOiJmYWtlYWxnIiwiZW5jIjoiZmFrZWVuYyIsImZha2VmaWVsZCI6ImZha2V2YWx1ZSJ9",
             "encrypted_key": "ZmFrZWtleQ",
             "iv": "cmFuZG9tZGF0YQ",
-            "aad": "ZmFrZWFhZA",
+            "aad": "fakeaad",
             "ciphertext": "ZmFrZWVuY291dHB1dA",
             "tag": "ZmFrZXRhZw"
         });