Add cipher.len check

.github/workflows/dusk_ci.yml

@@ -12,7 +12,7 @@ jobs:
     uses: dusk-network/.github/.github/workflows/code-analysis.yml@main
     with:
       clippy_default: false
-      clippy_args: -- -D warnings
+      clippy_args: --features=encryption -- -D warnings
 
   dusk_analyzer:
     name: Dusk Analyzer
@@ -21,3 +21,5 @@ jobs:
   test_nightly:
     name: Run tests
     uses: dusk-network/.github/.github/workflows/run-tests.yml@main
+    with:
+      test_flags: --features=encryption

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Add authenticated encryption and decryption [#6]
+- Add check for `cipher.len == message.len + 1` in `encrypt` and `decrypt` [#9]
 
 ### Changed
 
@@ -28,6 +29,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Add documentation
 
 <!-- ISSUES -->
+[#9]: https://github.com/dusk-network/safe/issues/9
 [#6]: https://github.com/dusk-network/safe/issues/6
 [#4]: https://github.com/dusk-network/safe/issues/4
 [#3]: https://github.com/dusk-network/safe/issues/3

src/encryption.rs

@@ -85,6 +85,11 @@ where
         cipher[i] = sponge.safe.add(&cipher[i], &message[i]);
     }
 
+    // cipher should yield exactly message_len + 1 elements
+    if cipher.len() != message_len + 1 {
+        return Err(Error::EncryptionFailed);
+    }
+
     // finish the sponge, erase cipher upon error
     match sponge.finish() {
         Ok(mut output) => {
@@ -93,7 +98,7 @@ where
         }
         Err(e) => {
             cipher.zeroize();
-            Err(e.into())
+            Err(e)
         }
     }
 }
@@ -118,7 +123,7 @@ where
         safe,
         domain_sep.into(),
         message_len,
-        &shared_secret,
+        shared_secret,
         &nonce,
     )?;
 
@@ -143,6 +148,11 @@ where
         return Err(Error::DecryptionFailed);
     };
 
+    // cipher should yield exactly message_len + 1 elements
+    if cipher.len() != message_len + 1 {
+        return Err(Error::DecryptionFailed);
+    }
+
     // finish sponge, erase message upon error
     match sponge.finish() {
         Ok(mut output) => {
@@ -151,7 +161,7 @@ where
         }
         Err(e) => {
             message.zeroize();
-            Err(e.into())
+            Err(e)
         }
     }
 }

src/error.rs

@@ -17,6 +17,10 @@ pub enum Error {
     /// The input doesn't yield enough input elements.
     TooFewInputElements,
 
+    /// Failed to encrypt the message into the cipher with the provided secret
+    /// and nonce.
+    EncryptionFailed,
+
     /// Failed to decrypt the message from the cipher with the provided secret
     /// and nonce.
     DecryptionFailed,