fix: do not use serde where it can be avoided

src/abe_policy/access_policy.rs

@@ -2,7 +2,6 @@ use crate::{
     abe_policy::{policy::Policy, Attribute},
     Error,
 };
-use serde::{Deserialize, Serialize};
 use std::{
     collections::HashMap,
     fmt::Debug,
@@ -12,7 +11,7 @@ use std::{
 /// An `AccessPolicy` is a boolean expression over attributes.
 ///
 /// Only `positive` literals are allowed (no negation).
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[derive(Debug, Clone)]
 pub enum AccessPolicy {
     Attr(Attribute),
     And(Box<AccessPolicy>, Box<AccessPolicy>),

src/abe_policy/policy.rs

@@ -143,19 +143,16 @@ pub struct Policy {
 
 impl Display for Policy {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let json = serde_json::to_string(&self);
-        match json {
-            Ok(string) => write!(f, "{string}"),
-            Err(err) => write!(f, "{err}"),
-        }
+        write!(f, "{self:?}")
     }
 }
 
 impl Policy {
     /// Converts the given string into a Policy. Does not fail if the given
     /// string uses the legacy format.
     pub fn parse_and_convert(bytes: &[u8]) -> Result<Self, Error> {
-        match serde_json::from_slice(bytes) {
+        // First try to deserialize the latest `Policy` format
+        match Policy::try_from(bytes) {
             Ok(policy) => Ok(policy),
             Err(e) => {
                 if let Ok(policy) = serde_json::from_slice::<LegacyPolicy>(bytes) {
@@ -180,9 +177,7 @@ impl Policy {
                             .collect(),
                     })
                 } else {
-                    // Return the `Policy` deserialization error message instead of the
-                    // `LegacyPolicy` one since this is the one that should be used.
-                    Err(Error::DeserializationError(e))
+                    Err(e)
                 }
             }
         }
@@ -577,7 +572,9 @@ mod tests {
         //
         // create policy
         let mut policy = policy()?;
+        println!("{policy:?}");
         policy.rotate(&Attribute::new("Department", "FIN"))?;
+        println!("{policy:?}");
 
         //
         // create access policy

tests/non_regression.rs

@@ -205,7 +205,7 @@ impl NonRegressionTestVector {
         let reg_vectors = Self {
             public_key: base64::encode(mpk.try_to_bytes()?),
             master_secret_key: base64::encode(msk.try_to_bytes()?),
-            policy: base64::encode(serde_json::to_vec(&policy)?),
+            policy: base64::encode(&policy.try_into()?),
             //
             // Create user decryption keys
             top_secret_mkg_fin_key: UserSecretKeyTestVector::new(