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Diffstat (limited to 'Assignment 3/nthkey.py')
| -rwxr-xr-x | Assignment 3/nthkey.py | 37 |
1 files changed, 0 insertions, 37 deletions
diff --git a/Assignment 3/nthkey.py b/Assignment 3/nthkey.py deleted file mode 100755 index 40cf0cf..0000000 --- a/Assignment 3/nthkey.py +++ /dev/null @@ -1,37 +0,0 @@ -#!/usr/bin/python - -# Copyright (c) 2015 Camil Staps <info@camilstaps.nl> - -import binascii - -# From http://stackoverflow.com/a/843846/1544337 -# 1 for odd parity, 0 for even parity -# Was used only in a previous version of nthByte -# def parity(b): -# c = 0 -# while b != 0: -# c += 1 -# b &= b - 1 -# return c % 2 - -# Find the nth possibility for a byte with odd parity -oddBytes = [1,2,4,7,8,11,13,14,16,19,21,22,25,26,28,31,32,35,37,38,41,42,44,47,49,50,52,55,56,59,61,62,64,67,69,70,73,74,76,79,81,82,84,87,88,91,93,94,97,98,100,103,104,107,109,110,112,115,117,118,121,122,124,127,128,131,133,134,137,138,140,143,145,146,148,151,152,155,157,158,161,162,164,167,168,171,173,174,176,179,181,182,185,186,188,191,193,194,196,199,200,203,205,206,208,211,213,214,217,218,220,223,224,227,229,230,233,234,236,239,241,242,244,247,248,251,253,254] -def nthByte(n): - return oddBytes[n] - # c = -1 # This is the old version. The new version uses a faster lookup table. - # b = 0 - # while c != n: - # b += 1 - # if parity(b) == 1: - # c += 1 - # return b - -# Find the nth key in which all bytes have odd parity -def nthKey(n): - key = '' - for b in range(7,-1,-1): - key += chr(nthByte((n >> b*7) & 0x7f)) - return key - -# Example -print binascii.b2a_hex(nthKey(765637))
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