Return a tuple from encrypt() instead of an EncryptionResult object

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Replaced `AsBackend`/`FromBackend`, `.inner()`, `.new()`, and `pub backend` with derived `AsRef`/`From`/`Into` where appropriate. (#[103])
 - Using a workaround with `wasm-bindgen-derive` to support `Option<&T>` and `&Vec<T>` arguments, and `Vec<T>` return values in WASM bindings. Generating correct TypeScript signatures in all the relevant cases. Affected API: `Capsule.decryptReencrypted()`, `KeyFrag.verify()`, `generate_kfrags()`. (#[103])
 - Removed `serde` usage in WASM bindings. ([#103])
+- `encrypt()` now returns an actual tuple in WASM bindings instead of a special object. (#[103])
 
 
 ### Added

umbral-pre-wasm/README.md

@@ -36,10 +36,7 @@ let bob_pk = bob_sk.publicKey();
 let plaintext = "Plaintext message";
 let plaintext_bytes = enc.encode(plaintext);
 
-// The API here slightly differs from that in Rust.
-// Since wasm-pack does not support returning tuples, we return an object containing
-// the ciphertext and the capsule.
-let {capsule, ciphertext} = umbral.encrypt(alice_pk, plaintext_bytes);
+let [capsule, ciphertext] = umbral.encrypt(alice_pk, plaintext_bytes);
 let ciphertext = result.ciphertext;
 let capsule = result.capsule;
 

umbral-pre-wasm/examples/bundler/index.js

@@ -24,10 +24,7 @@ let bob_pk = bob_sk.publicKey();
 let plaintext = "Plaintext message";
 let plaintext_bytes = enc.encode(plaintext);
 
-// The API here slightly differs from that in Rust.
-// Since wasm-pack does not support returning tuples, we return an object containing
-// the ciphertext and the capsule.
-let {capsule, ciphertext} = umbral.encrypt(alice_pk, plaintext_bytes);
+let [capsule, ciphertext] = umbral.encrypt(alice_pk, plaintext_bytes);
 
 // Since data was encrypted with Alice's public key, Alice can open the capsule
 // and decrypt the ciphertext with her private key.

umbral-pre-wasm/examples/node/index.js

@@ -24,10 +24,7 @@ let bob_pk = bob_sk.publicKey();
 let plaintext = "Plaintext message";
 let plaintext_bytes = enc.encode(plaintext);
 
-// The API here slightly differs from that in Rust.
-// Since wasm-pack does not support returning tuples, we return an object containing
-// the ciphertext and the capsule.
-let {capsule, ciphertext} = umbral.encrypt(alice_pk, plaintext_bytes);
+let [capsule, ciphertext] = umbral.encrypt(alice_pk, plaintext_bytes);
 
 // Since data was encrypted with Alice's public key, Alice can open the capsule
 // and decrypt the ciphertext with her private key.

umbral-pre-wasm/examples/react/src/App.js

@@ -49,10 +49,7 @@ function App() {
 
     let plaintext_bytes = enc.encode(plaintext);
 
-    // The API here slightly differs from that in Rust.
-    // Since wasm-pack does not support returning tuples, we return an object containing
-    // the ciphertext and the capsule.
-    let {capsule, ciphertext} = umbral.encrypt(alice_pk, plaintext_bytes);
+    let [capsule, ciphertext] = umbral.encrypt(alice_pk, plaintext_bytes);
 
     // Since data was encrypted with Alice's public key, Alice can open the capsule
     // and decrypt the ciphertext with her private key.

umbral-pre/src/bindings_wasm.rs

@@ -14,7 +14,7 @@ use alloc::string::String;
 use alloc::vec::Vec;
 use core::fmt;
 
-use js_sys::Error;
+use js_sys::{Error, Uint8Array};
 use wasm_bindgen::prelude::{wasm_bindgen, JsValue};
 use wasm_bindgen::JsCast;
 use wasm_bindgen_derive::TryFromJsValue;
@@ -32,6 +32,9 @@ extern "C" {
 
     #[wasm_bindgen(typescript_type = "VerifiedKeyFrag[]")]
     pub type VerifiedKeyFragArray;
+
+    #[wasm_bindgen(typescript_type = "[Capsule, Uint8Array]")]
+    pub type EncryptionResult;
 }
 
 fn map_js_err<T: fmt::Display>(err: T) -> Error {
@@ -370,35 +373,19 @@ impl VerifiedCapsuleFrag {
     }
 }
 
-#[wasm_bindgen]
-pub struct EncryptionResult {
-    ciphertext: Box<[u8]>,
-    pub capsule: Capsule,
-}
-
-#[wasm_bindgen]
-impl EncryptionResult {
-    fn new(ciphertext: Box<[u8]>, capsule: Capsule) -> Self {
-        Self {
-            ciphertext,
-            capsule,
-        }
-    }
-
-    // TODO (#24): currently can't just make the field public because `Box` doesn't implement `Copy`.
-    // See https://github.com/rustwasm/wasm-bindgen/issues/439
-    #[wasm_bindgen(getter)]
-    pub fn ciphertext(&self) -> Box<[u8]> {
-        self.ciphertext.clone()
-    }
-}
-
 #[wasm_bindgen]
 pub fn encrypt(delegating_pk: &PublicKey, plaintext: &[u8]) -> Result<EncryptionResult, Error> {
     let backend_pk = delegating_pk.0;
-    umbral_pre::encrypt(&backend_pk, plaintext)
-        .map(|(capsule, ciphertext)| EncryptionResult::new(ciphertext, Capsule(capsule)))
-        .map_err(map_js_err)
+    let (capsule, ciphertext) = umbral_pre::encrypt(&backend_pk, plaintext).map_err(map_js_err)?;
+
+    // TODO (#24): wasm-bindgen does not allow one to return a tuple directly.
+    // Have to cast it manually.
+    let capsule_js: JsValue = Capsule::from(capsule).into();
+    let ciphertext_js: JsValue = Uint8Array::from(ciphertext.as_ref()).into();
+    Ok([capsule_js, ciphertext_js]
+        .into_iter()
+        .collect::<js_sys::Array>()
+        .unchecked_into::<EncryptionResult>())
 }
 
 #[wasm_bindgen(js_name = decryptOriginal)]