Added a unit test for cypher text padding check in client's symmetric_decrypt_verify()

lib/src/core/comms/secure_channel.rs

@@ -1212,10 +1212,13 @@ impl SecureChannel {
 
                 // There is an expectation that the block is padded so, this is a quick test
                 let ciphertext_size = encrypted_range.end - encrypted_range.start;
-                //                if ciphertext_size % 16 != 0 {
-                //                    error!("The cipher text size is not padded properly, size = {}", ciphertext_size);
-                //                    return Err(StatusCode::BadUnexpectedError);
-                //                }
+                if ciphertext_size % 16 != 0 {
+                    error!(
+                        "The cipher text size is not padded properly, size = {}",
+                        ciphertext_size
+                    );
+                    return Err(StatusCode::BadUnexpectedError);
+                }
 
                 // Copy security header
                 dst[..encrypted_range.start].copy_from_slice(&src[..encrypted_range.start]);

lib/src/core/tests/chunk.rs

@@ -472,6 +472,33 @@ fn security_policy_symmetric_encrypt_decrypt() {
     assert_eq!(&src[..80], &src2[..80]);
 }
 
+#[test]
+fn security_policy_symmetric_encrypt_decrypt_ciphertext_invalid_padding_returns_error() {
+    let (secure_channel1, secure_channel2) = make_secure_channels(
+        MessageSecurityMode::SignAndEncrypt,
+        SecurityPolicy::Basic128Rsa15,
+    );
+
+    let src = vec![0u8; 100];
+    let mut dst = vec![0u8; 200];
+
+    let encrypted_len = secure_channel1
+        .symmetric_sign_and_encrypt(&src, 0..80, 20..100, &mut dst)
+        .unwrap();
+    assert_eq!(encrypted_len, 100);
+
+    let mut src2 = vec![0u8; 200];
+
+    // length of encrypted range should be dividable by 16
+    let invalid_encrypted_range = 21..100;
+
+    let error = secure_channel2
+        .symmetric_decrypt_and_verify(&dst, 0..80, invalid_encrypted_range, &mut src2)
+        .unwrap_err();
+
+    assert!(error.contains(StatusCode::BadUnexpectedError))
+}
+
 #[test]
 fn asymmetric_decrypt_and_verify_sample_chunk() {
     let _ = Test::setup();