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replacing magic numbers with consts, opting for list-based rather than string-based stuff in most places

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This commit is contained in:
Dan Buch 2009-11-26 08:44:05 -05:00
parent 8cf3df0e3e
commit ca11fa5f32
2 changed files with 30 additions and 13 deletions
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28
onetimepad.py
View File

@ -1,5 +1,10 @@
import random import random
PAD_MODULO = 3
DEFAULT_PAD_WIDTH = 72
CIPHER_FLOOR = 1
CIPHER_CEIL = 25
def encode(msg, pad): def encode(msg, pad):
return msg return msg
@ -9,27 +14,34 @@ def decode(msg, pad):
return msg return msg
def create_pad(length, width=72): def create_pad(length, width=DEFAULT_PAD_WIDTH):
return '\n'.join(create_pad_lines(length, width=width))
def create_pad_lines(length, width=DEFAULT_PAD_WIDTH):
chars = _create_chars_for_pad(length) chars = _create_chars_for_pad(length)
lines = _chunk_chars_into_lines(chars, width=width) lines = _chunk_chars_into_lines(chars, width=width)
return '\n\n\n'.join(lines) for line in lines:
yield line
yield ''
yield ''
def _create_chars_for_pad(length): def _create_chars_for_pad(length):
chars = [] chars = []
for char in range(length): for char in range(length):
chars.append(_AS_ALPHA[random.randint(1, 25)]) chars.append(_AS_ALPHA[random.randint(CIPHER_FLOOR, CIPHER_CEIL)])
return ''.join(chars) return ''.join(chars)
def _chunk_chars_into_lines(chars, width=72): def _chunk_chars_into_lines(chars, width=DEFAULT_PAD_WIDTH):
lines = [] lines = []
for chunk in _as_line_chunks(chars, width=width): for chunk in _as_line_chunks(chars, width=width):
lines.append(chunk) lines.append(chunk)
return lines return lines
def _as_line_chunks(chars, width=72): def _as_line_chunks(chars, width=DEFAULT_PAD_WIDTH):
chunk = [] chunk = []
for char in chars: for char in chars:
chunk.append(char) chunk.append(char)
@ -57,11 +69,11 @@ def _get_textwidth(text):
def _is_padline(lineno): def _is_padline(lineno):
return not lineno % 3 return not lineno % PAD_MODULO
def _is_txtline(lineno): def _is_txtline(lineno):
return (lineno % 2 and not lineno % 3) return (lineno % 2 and not lineno % PAD_MODULO)
def _is_cipherline(lineno): def _is_cipherline(lineno):
@ -73,7 +85,7 @@ def _mk_as_alpha():
a_chr = ord('A') a_chr = ord('A')
past_j = False past_j = False
for char in range(26): for char in range(CIPHER_CEIL + 1):
letter = chr(a_chr + char) letter = chr(a_chr + char)
if letter != 'J': if letter != 'J':
key = char + (1 if not past_j else 0) key = char + (1 if not past_j else 0)

15
test_onetimepad.py
View File

@ -5,6 +5,7 @@ import onetimepad as OT
class TestOneTimePad(unittest.TestCase): class TestOneTimePad(unittest.TestCase):
msg = ('HOWMUCHCHUCKCOULDAWOODCHUCKCHUCKIFA' msg = ('HOWMUCHCHUCKCOULDAWOODCHUCKCHUCKIFA'
'WOODCHUCKCOULDCHUCKWOOD' * 50) 'WOODCHUCKCOULDCHUCKWOOD' * 50)
_padsize = 2000
def test_mk_as_alpha_excludes_j(self): def test_mk_as_alpha_excludes_j(self):
self.assertTrue('J' not in OT._AS_ALPHA.values()) self.assertTrue('J' not in OT._AS_ALPHA.values())
@ -14,13 +15,17 @@ class TestOneTimePad(unittest.TestCase):
def test_creates_pad_of_desired_length(self): def test_creates_pad_of_desired_length(self):
for width in (72, 33, 99, 111): for width in (72, 33, 99, 111):
pad = OT.create_pad(2000, width=width) pad = OT.create_pad(self._padsize, width=width)
lines = [line.strip('.') for line in pad.split('\n\n\n')] lines = [line.strip('.') for line in pad.split()]
self.assertEqual(2000, len(''.join(lines))) actual = len(''.join(lines))
self.assertEqual(self._padsize, len(''.join(lines)),
'pad of {0} chars created at width '
'{1}, actual={2}'.format(self._padsize,
width, actual))
def test_two_out_of_every_three_lines_are_empty_on_new_pad(self): def test_two_out_of_every_three_lines_are_empty_on_new_pad(self):
pad = OT.create_pad(2000) pad = OT.create_pad_lines(2000)
for lineno, line in enumerate(pad.splitlines()): for lineno, line in enumerate(pad):
line = line.strip() line = line.strip()
if OT._is_padline(lineno): if OT._is_padline(lineno):
self.assertTrue(bool(len(line)), self.assertTrue(bool(len(line)),