Thread 'async' through any protocol APIs that take Stores

In preparation for Desktop, which must asynchronously access its
database (rather than putting the entire operation on a background
thread with synchronization at the database layer).

The FFI and JNI wrappers (as well as the tests) use
futures::executor::block_on to turn the operations back into
synchronous ones.

rust/protocol/tests/support/mod.rs

@@ -15,7 +15,7 @@ pub fn test_in_memory_protocol_store() -> InMemSignalProtocolStore {
 }
 
 #[allow(dead_code)]
-pub fn encrypt(
+pub async fn encrypt(
     store: &mut InMemSignalProtocolStore,
     remote_address: &ProtocolAddress,
     msg: &str,
@@ -26,11 +26,11 @@ pub fn encrypt(
         &mut store.session_store,
         &mut store.identity_store,
         None,
-    )
+    ).await
 }
 
 #[allow(dead_code)]
-pub fn decrypt(
+pub async fn decrypt(
     store: &mut InMemSignalProtocolStore,
     remote_address: &ProtocolAddress,
     msg: &CiphertextMessage,
@@ -45,11 +45,11 @@ pub fn decrypt(
         &mut store.signed_pre_key_store,
         &mut csprng,
         None,
-    )
+    ).await
 }
 
 #[allow(dead_code)]
-pub fn create_pre_key_bundle<R: Rng + CryptoRng>(
+pub async fn create_pre_key_bundle<R: Rng + CryptoRng>(
     store: &mut dyn ProtocolStore,
     mut csprng: &mut R,
 ) -> Result<PreKeyBundle, SignalProtocolError> {
@@ -58,7 +58,7 @@ pub fn create_pre_key_bundle<R: Rng + CryptoRng>(
 
     let signed_pre_key_public = signed_pre_key_pair.public_key.serialize();
     let signed_pre_key_signature = store
-        .get_identity_key_pair(None)?
+        .get_identity_key_pair(None).await?
         .private_key()
         .calculate_signature(&signed_pre_key_public, &mut csprng)?;
 
@@ -67,21 +67,21 @@ pub fn create_pre_key_bundle<R: Rng + CryptoRng>(
     let signed_pre_key_id: u32 = csprng.gen();
 
     let pre_key_bundle = PreKeyBundle::new(
-        store.get_local_registration_id(None)?,
+        store.get_local_registration_id(None).await?,
         device_id,
         Some(pre_key_id),
         Some(pre_key_pair.public_key),
         signed_pre_key_id,
         signed_pre_key_pair.public_key,
         signed_pre_key_signature.to_vec(),
-        *store.get_identity_key_pair(None)?.identity_key(),
+        *store.get_identity_key_pair(None).await?.identity_key(),
     )?;
 
     store.save_pre_key(
         pre_key_id,
         &PreKeyRecord::new(pre_key_id, &pre_key_pair),
         None,
-    )?;
+    ).await?;
 
     let timestamp = csprng.gen();
 
@@ -94,7 +94,7 @@ pub fn create_pre_key_bundle<R: Rng + CryptoRng>(
             &signed_pre_key_signature,
         ),
         None,
-    )?;
+    ).await?;
 
     Ok(pre_key_bundle)
 }