crypto add arbitrary purpose

src/crypto.rs

@@ -10,8 +10,8 @@ use sp_client::{
         Txid,
     },
     silentpayments::{
-        sending::SilentPaymentAddress, 
-        bitcoin_hashes::{sha256t_hash_newtype, HashEngine, Hash}
+        bitcoin_hashes::{sha256t_hash_newtype, Hash, HashEngine},
+        sending::SilentPaymentAddress,
     },
 };
 
@@ -47,7 +47,7 @@ impl AnkSharedSecret {
         Self(SharedSecret::from_bytes(t_hash.to_byte_array()))
     }
 
-    pub fn to_byte_array(&self) -> [u8;SECRET_KEY_SIZE] {
+    pub fn to_byte_array(&self) -> [u8; SECRET_KEY_SIZE] {
         self.0.secret_bytes()
     }
 
@@ -99,6 +99,7 @@ impl HalfKey {
 pub enum Purpose {
     Login,
     ThirtyTwoBytes,
+    Arbitrary,
 }
 
 pub type CipherText = Vec<u8>;
@@ -166,6 +167,10 @@ impl Aes256Decryption {
                 let thirty_two_buf = self.decrypt_thirty_two()?;
                 Ok(thirty_two_buf.to_vec())
             }
+            Purpose::Arbitrary => {
+                let arbitrary = self.decrypt_arbitrary()?;
+                Ok(arbitrary)
+            }
         }
     }
 
@@ -194,6 +199,14 @@ impl Aes256Decryption {
         thirty_two.copy_from_slice(&plain);
         Ok(thirty_two)
     }
+
+    fn decrypt_arbitrary(&self) -> Result<Vec<u8>> {
+        let cipher = Aes256Gcm::new(&self.aes_key.into());
+        let plain = cipher
+            .decrypt(&self.nonce.into(), &*self.cipher_text)
+            .map_err(|e| Error::msg(format!("{}", e)))?;
+        Ok(plain)
+    }
 }
 
 pub struct Aes256Encryption {
@@ -266,6 +279,7 @@ impl Aes256Encryption {
         match self.purpose {
             Purpose::Login => self.encrypt_login(),
             Purpose::ThirtyTwoBytes => self.encrypt_thirty_two(),
+            Purpose::Arbitrary => self.encrypt_arbitrary(),
         }
     }
 
@@ -296,6 +310,17 @@ impl Aes256Encryption {
         res.extend_from_slice(&cipher_text);
         Ok(res)
     }
+
+    fn encrypt_arbitrary(&self) -> Result<CipherText> {
+        let cipher = Aes256Gcm::new(&self.aes_key.into());
+        let cipher_text = cipher
+            .encrypt(&self.nonce.into(), &*self.plaintext)
+            .map_err(|e| Error::msg(format!("{}", e)))?;
+        let mut res = Vec::with_capacity(self.nonce.len() + cipher_text.len());
+        res.extend_from_slice(&self.nonce);
+        res.extend_from_slice(&cipher_text);
+        Ok(res)
+    }
 }
 
 #[cfg(test)]