diff --git a/src/aes.rs b/src/aes.rs
index 8baa796c..7f8bc19e 100644
--- a/src/aes.rs
+++ b/src/aes.rs
@@ -17,6 +17,11 @@ const AUTH_CODE_LENGTH: usize = 10;
 /// The number of iterations used with PBKDF2
 const ITERATION_COUNT: u32 = 1000;
 
+/// Create a AesCipher depending on the used `AesMode` and the given `key`.
+/// 
+/// # Panics
+///
+/// This panics if `key` doesn't have the correct size for the chosen aes mode.
 fn cipher_from_mode(aes_mode: AesMode, key: &[u8]) -> Box<dyn aes_ctr::AesCipher> {
     match aes_mode {
         AesMode::Aes128 => Box::new(aes_ctr::AesCtrZipKeyStream::<aes_ctr::Aes128>::new(key))
@@ -127,6 +132,11 @@ impl<R: Read> AesReader<R> {
     }
 }
 
+/// A reader for aes encrypted files, which has already passed the first password check.
+///
+/// There is a 1 in 65536 chance that an invalid password passes that check.
+/// After the data has been read and decrypted an HMAC will be checked and provide a final means
+/// to check if either the password is invalid or if the data has been changed.
 pub struct AesReaderValid<R: Read> {
     reader: R,
     data_remaining: u64,
diff --git a/src/aes_ctr.rs b/src/aes_ctr.rs
index e23eb3bb..307c7530 100644
--- a/src/aes_ctr.rs
+++ b/src/aes_ctr.rs
@@ -85,6 +85,10 @@ where
     C::Cipher: NewBlockCipher,
 {
     /// Creates a new zip variant AES-CTR key stream.
+    ///
+    /// # Panics
+    ///
+    /// This panics if `key` doesn't have the correct size for cipher `C`.
     pub fn new(key: &[u8]) -> AesCtrZipKeyStream<C> {
         AesCtrZipKeyStream {
             counter: 1,