#!/usr/bin/env python #Takes a string as an argument and returns 3 base64 encoded string partials. #One of these strings is guaranteed to be present in the base64 content if #the original plain-text code contained the (case-sensitive) input string. #Due to the 8 bit to 6 bit encoding conversion involved in base64 encoding, #the edges don't always align nicely, so trimming is required as the first #and last characters may be different depending on the immediate context. from base64 import b64encode import sys def main(input): L_offset = 0 R_offset = 3 - ((len(input) + L_offset) % 3) if (R_offset == 3): R_offset = 0 e1, e2, e3 = encode(input) e1 = trim(e1, L_offset, R_offset) L_offset += 1 R_offset = 3 - ((len(input) + L_offset) % 3) if (R_offset == 3): R_offset = 0 e2 = trim(e2, L_offset, R_offset) L_offset += 1 R_offset = 3 - ((len(input) + L_offset) % 3) if (R_offset == 3): R_offset = 0 e3 = trim(e3, L_offset, R_offset) print(e1) print(e2) print(e3) def offset_2_chars(offset): if (offset == 0): return 0 elif (offset == 1): return 2 else: return 3 def trim(input, L_offset, R_offset): input = trimL(input, L_offset) input = trimR(input, R_offset) return input def trimL(input, offset): left_cut = offset_2_chars(offset) return input[left_cut:] def trimR(input, offset): if (offset == 0): return input right_cut = offset_2_chars(offset) return input[:-right_cut] def encode(input): e1 = b64encode(input) e2 = b64encode('0' + input) e3 = b64encode('00' + input) return e1, e2, e3 if __name__ == '__main__': main(sys.argv[1])