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dhondtadhondta
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Added new codec: scytale
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Lines changed: 86 additions & 2 deletions

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‎README.md‎

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@@ -31,6 +31,7 @@ This library extends the native `codecs` library and provides some new encodings
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`radio` | text <-> radio words | aka NATO or radio phonetic alphabet
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`resistor` | text <-> resistor colors | aka resistor color codes
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`rot` | text <-> rot(N) ciphertext | aka Caesar cipher (N belongs to [1,25])
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`scytale` | text <-> scytale ciphertext | encrypts with L, the number of letters on the rod (belongs to [1,[)
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`shift` | text <-> shift(N) ciphertext | shift ordinals with N (belongs to [1,255])
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`sms` | text <-> phone keystrokes | also called T9 code ; uses "`-`" as a separator for encoding, "`-`" or "`_`" or whitespace for decoding
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`url` | text <-> URL encoded text | aka URL encoding

‎codext/crypto/__init__.py‎

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from .atbash import *
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from .bacon import *
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from .barbie import *
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from .rotn import *
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from .rot import *
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from .scytale import *
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from .shift import *
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from .xor_byte import *
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from .xor import *
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‎codext/crypto/scytale.py‎

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# -*- coding: UTF-8 -*-
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"""Scytale-N Codec - scytale content encoding.
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This codec:
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- en/decodes strings from str to str
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- en/decodes strings from bytes to bytes
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- decodes file content to str (read)
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- encodes file content from str to bytes (write)
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"""
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from math import ceil
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from ..__common__ import *
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PADDING_CHAR = ""
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def scytale_encode(l):
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def encode(text, errors="strict"):
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s, n = "", int(ceil(len(text) / float(l)))
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for x in range(l):
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for y in range(n):
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try:
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s += text[y*l+x]
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except IndexError:
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s += PADDING_CHAR
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return s, len(s)
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return encode
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def scytale_decode(l):
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def decode(text, errors="strict"):
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s, n = "", int(ceil(len(text) / float(l)))
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pl = l * n - len(text)
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for x in range(n):
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for y in range(l):
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if y >= l-pl and x == n-1:
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continue
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s += text[y*n+x-max(0,y-(l-pl))]
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s = s.rstrip(PADDING_CHAR)
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return s, len(s)
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return decode
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add("scytale", scytale_encode, scytale_decode, r"(?i)scytale[-_]?([1-9]\d*)$")
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‎tests/test_scytale.py‎

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#!/usr/bin/env python
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# -*- coding: UTF-8 -*-
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"""Scytale-N codecs tests.
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"""
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import os
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from unittest import TestCase
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from codext.__common__ import *
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class TestCodecsScytale(TestCase):
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def test_codecs_scytale(self):
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STR = "this is a test"
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SC2 = "ti satshsi et"
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SC5 = "tithsei ssat "
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TFILE = "test-codec-scytale.txt"
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self.assertEqual(codecs.encode(STR, "scytale2"), SC2)
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self.assertEqual(codecs.encode(STR, "scytale-2"), SC2)
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self.assertEqual(codecs.encode(STR, "scytale_2"), SC2)
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self.assertEqual(codecs.encode(STR, "scytale-5"), SC5)
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self.assertEqual(codecs.encode(STR, "scytale_5"), SC5)
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self.assertEqual(codecs.decode(SC5, "scytale5"), STR)
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self.assertRaises(LookupError, codecs.decode, STR, "scytale0")
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self.assertRaises(LookupError, codecs.decode, STR, "scytale--10")
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self.assertRaises(LookupError, codecs.decode, STR, "scytale01")
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with codecs.open(TFILE, 'w', encoding="scytale-5") as f:
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f.write(b(STR))
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with open(TFILE) as f:
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r = f.read()
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self.assertEqual(SC5, r)
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with codecs.open(TFILE, encoding="scytale-5") as f:
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s = f.read()
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self.assertEqual(STR, ensure_str(s))
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os.remove(TFILE)
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