updated readme

README.md

@@ -42,11 +42,17 @@ $associatedData = "Some data 😋 文 This data is not contained in the encrypt
 $encrypted = Ascon::encryptToHex($key, $message, $associatedData);
 $decrypted = Ascon::decryptFromHex($key, $encrypted, $associatedData);
 
-// raw usage (the original implementation with raw values)
+// key must be 16 bytes or 20 bytes, depending on variant
 $key = [0x90, 0x80, 0x70, 0x60, 0x50, 0x40, 0x30, 0x20, 0x10, 0xAA, 0x90, 0x90, 0x90, 0x90, 0xCC, 0xEF];
+// nonce must be 16 bytes and should always be random bytes, you must use same nonce for encrypt and decrypt the same message
 $nonce = random_bytes(16);
+// this is the text you want to encrypt
 $plaintext = "Hi, i am a secret message!";
-$associatedData = "Some data the will not be encrypted but verified along the plaintext (Decryption will fail if you not provide the exact same data)";
+// associated data is not being encrypted, but is taken into account in the ciphertext
+// this means, you can only decrypt when you pass the exact same associated data to the decrypt function as well
+// so you can make sure that associated data and plaintext is not manipulated for given encrypted message
+// this is optional and can be an empty string
+$associatedData = "Some data to pass to encryption and decryption - This data is not contained in the ciphertext output.";
 $ciphertextByteArray = Ascon::encrypt($key, $nonce, $associatedData, $plaintext);
 $plaintextDecrypted = Ascon::decrypt($key, $nonce, $associatedData, $ciphertextByteArray);
 ```