feat!: update encrypt api to take dbc id

- This improves the type safety.

src/dbc_ciphers.rs

@@ -71,7 +71,7 @@ impl From<(&PublicAddress, &DerivationIndex, RevealedAmount)> for DbcCiphers {
         let derivation_index_cipher = public_address.encrypt(derivation_index);
         let revealed_amount_cipher = public_address
             .new_dbc_id(derivation_index)
-            .encrypt(revealed_amount);
+            .encrypt(&revealed_amount);
 
         Self {
             public_address: *public_address,

src/dbc_id.rs

@@ -37,7 +37,7 @@ impl DbcId {
         self.0.verify(sig, msg)
     }
 
-    pub fn encrypt(&self, revealed_amount: RevealedAmount) -> Ciphertext {
+    pub fn encrypt(&self, revealed_amount: &RevealedAmount) -> Ciphertext {
         self.0.encrypt(revealed_amount.to_bytes())
     }
 }

src/transaction/amount.rs

@@ -4,9 +4,9 @@
 // This SAFE Network Software is licensed under the BSD-3-Clause license.
 // Please see the LICENSE file for more details.
 
-use crate::{rand::RngCore, BlindedAmount, BlindingFactor, DerivedKey, Error, Result};
+use crate::{rand::RngCore, BlindedAmount, BlindingFactor, DbcId, DerivedKey, Error, Result};
 
-use blsttc::{rand::CryptoRng, Ciphertext, PublicKey};
+use blsttc::{rand::CryptoRng, Ciphertext};
 use bulletproofs::PedersenGens;
 use std::convert::TryFrom;
 
@@ -56,9 +56,9 @@ impl RevealedAmount {
         self.blinding_factor
     }
 
-    /// Encrypt this instance to given public key, producing `Ciphertext`.
-    pub fn encrypt(&self, public_key: &PublicKey) -> Ciphertext {
-        public_key.encrypt(self.to_bytes())
+    /// Encrypt this instance to given `DbcId`, producing `Ciphertext`.
+    pub fn encrypt(&self, dbc_id: &DbcId) -> Ciphertext {
+        dbc_id.encrypt(self)
     }
 
     /// Build RevealedAmount from fixed size byte array.