Stegano/tools.py
2010-10-05 07:25:00 +02:00

83 lines
No EOL
2.1 KiB
Python
Executable file

#! /usr/local/bin/python
# -*- coding: utf-8 -*-
def a2bits(chars):
"""
Converts a string to its bits representation as a string of 0's and 1's.
>>> a2bits("Hello World!")
'010010000110010101101100011011000110111100100000010101110110111101110010011011000110010000100001'
"""
return bin(reduce(lambda x, y : (x<<8)+y, (ord(c) for c in chars), 1))[3:]
def a2bits_list(chars):
"""
Convert a string to its bits representation as a list of 0's and 1's.
>>> a2bits_list("Hello World!")
['01001000',
'01100101',
'01101100',
'01101100',
'01101111',
'00100000',
'01010111',
'01101111',
'01110010',
'01101100',
'01100100',
'00100001']
>>> "".join(a2bits_list("Hello World!"))
'010010000110010101101100011011000110111100100000010101110110111101110010011011000110010000100001'
"""
return [bin(ord(x))[2:].rjust(8,"0") for x in chars]
def bs(s):
"""
Converts an int to its bits representation as a string of 0's and 1's.
"""
return str(s) if s<=1 else bs(s>>1) + str(s&1)
def setlsb(component, bit):
"""
Set Least Significant Bit of a colour component.
"""
return component & ~1 | int(bit)
def n_at_a_time(items, n, fillvalue):
"""
Returns an iterator which groups n items at a time.
Any final partial tuple will be padded with the fillvalue
>>> list(n_at_a_time([1, 2, 3, 4, 5], 2, 'X'))
[(1, 2), (3, 4), (5, 'X')]
"""
it = iter(items)
return its.izip_longest(*[it] * n, fillvalue=fillvalue)
def binary2base64(binary_file, output_file):
"""
"""
# use mode = "rb" to read binary file
fin = open(binary_file, "rb")
binary_data = fin.read()
fin.close()
# encode binary to base64 string (printable)
b64_data = base64.b64encode(binary_data)
fout = open(output_file, "w")
fout.write(b64_data)
fout.close
def base642binary(b64_fname):
"""
"""
# read base64 string
fin = open(b64_fname, "r")
b64_str = fin.read()
fin.close()
# decode base64 string to original binary sound object
return base64.b64decode(b64_str)