diff --git a/libs/derive_string.py b/libs/derive_string.py
index 0b18952..06ecebd 100644
--- a/libs/derive_string.py
+++ b/libs/derive_string.py
@@ -1,10 +1,16 @@
 #!/usr/bin/env python
 
 from hashlib import sha3_256
-from itertools import count
+from itertools import count, islice
 from Crypto.Cipher import ChaCha20
 from math import floor, ceil
 from time import sleep
+from os import environ
+from sys import stderr
+
+def debug(*args):
+    if 'DEBUG' in environ:
+        print(*args, file=stderr)
 
 def chacha_bits(input, bit_count):
     zerobyte = (0).to_bytes(length=1, byteorder='big')
@@ -12,36 +18,37 @@ def chacha_bits(input, bit_count):
     i = 0
 
     while True:
-        print('-----------------------------')
+        debug(f'--- BITS {i} ---')
         start_bit = bit_count * i
         start_byte = start_bit // 8
         start_padding = start_bit % 8
-        print('start_bit', start_bit)
-        print('start_byte', start_byte)
-        print('start_padding', start_padding)
+        debug('start_bit', start_bit)
+        debug('start_byte', start_byte)
+        debug('start_padding', start_padding)
 
         end_bit = bit_count * i + bit_count
         end_byte = end_bit // 8
         end_padding = 8 - (end_bit % 8)
-        print('end_bit', end_bit)
-        print('end_byte', end_byte)
-        print('end_padding', end_padding)
+        debug('end_bit', end_bit)
+        debug('end_byte', end_byte)
+        debug('end_padding', end_padding)
         
         byte_count = (end_byte - start_byte) + 1
-        print('byte_count', byte_count)
+        debug('byte_count', byte_count)
 
         cipher.seek(start_byte)
-        ciphertext = cipher.encrypt(zerobyte*byte_count)
-        print('ciphertext', bin(int.from_bytes(ciphertext, byteorder='big')))
-        shifted_ciphertext = int.from_bytes(ciphertext, byteorder='big') >> end_padding
-        print('shifted_ciphertext', bin(shifted_ciphertext))
+        cipherint = int.from_bytes(cipher.encrypt(zerobyte*byte_count), byteorder='big')
+        debug('ciphertext', bin(cipherint))
+        shifted_cipherint = cipherint >> end_padding
+        debug('shifted_ciphertext', bin(shifted_cipherint))
         
         bit_mask = int('1'*bit_count, 2)
-        print('bit_mask', bin(bit_mask))
-        masked_ciphertext = shifted_ciphertext & bit_mask
-        print('masked_ciphertext', bin(masked_ciphertext))
+        debug('bit_mask', bin(bit_mask))
+        masked_cipherint = shifted_cipherint & bit_mask
+        debug('masked_ciphertext', bin(masked_cipherint))
 
-        yield masked_ciphertext
+        debug('')
+        yield masked_cipherint
         i += 1
 
 
@@ -49,15 +56,15 @@ def chacha_chracter(input, choices):
     get_bits = chacha_bits(input, len(choices).bit_length())
     
     while True:
-        choice = next(get_bits)
-        if choice < len(choices):
-            yield choices[choice]
+        key = next(get_bits)
+        if key < len(choices):
+            yield choices[key]
 
 
 def derive_string(input, length, choices):
     get_character = chacha_chracter(input, choices)
-    return ''.join(next(get_character) for i in range(length))
+    return bytes(islice(get_character, length))
 
 print(
-    derive_string(b'12345', length=100, choices='abcdefghijklmnopqrstuvwxyz0123456789')
+    derive_string(b'12344', length=100, choices=b'abcdefghijklmnopqrstuvwxyz0123456789')
 )