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dhondtadhondta
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Added bacon codec
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‎codext/crypto/bacon.py‎

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# -*- coding: UTF-8 -*-
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"""Bacon's Cipher Codec - bacon 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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Reference: https://en.wikipedia.org/wiki/Bacon%27s_cipher
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"""
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from ..__common__ import *
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ENCMAP = {
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'A': "aaaaa",
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}
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REPLACE_CHAR = "?"
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#FIXME
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"""
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VERSION 1
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Letter Code Binary
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A aaaaa 00000
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B aaaab 00001
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C aaaba 00010
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D aaabb 00011
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E aabaa 00100
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F aabab 00101
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G aabba 00110
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H aabbb 00111
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I, J abaaa 01000
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K abaab 01001
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L ababa 01010
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M ababb 01011
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Letter Code Binary
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N abbaa 01100
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O abbab 01101
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P abbba 01110
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Q abbbb 01111
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R baaaa 10000
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S baaab 10001
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T baaba 10010
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U, V baabb 10011
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W babaa 10100
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X babab 10101
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Y babba 10110
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Z babbb 10111
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Letter Code Binary
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A aaaaa 00000
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B aaaab 00001
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C aaaba 00010
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D aaabb 00011
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E aabaa 00100
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F aabab 00101
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G aabba 00110
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H aabbb 00111
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I abaaa 01000
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J abaab 01001
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K ababa 01010
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L ababb 01011
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M abbaa 01100
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VERSION 2
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Letter Code Binary
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N abbab 01101
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O abbba 01110
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P abbbb 01111
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Q baaaa 10000
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R baaab 10001
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S baaba 10010
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T baabb 10011
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U babaa 10100
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V babab 10101
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W babba 10110
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X babbb 10111
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Y bbaaa 11000
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Z bbaab 11001
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"""
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class BaconError(ValueError):
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pass
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class BaconDecodeError(BaconError):
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pass
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class BaconEncodeError(BaconError):
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pass
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def bacon_encode(code):
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def encode(text, errors="strict"):
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std0, stdn = [c for c in STD[0]], [c for c in STD[code]]
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spec0, specn = SPEC[0].split(), SPEC[code].split()
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mapping = {d: e for d, e in zip(std0 + spec0, stdn + specn)}
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r = ""
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for i, c in enumerate(ensure_str(text)):
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try:
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r += mapping[c]
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except KeyError:
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if errors == "strict":
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raise BaconEncodeError("'bacon' codec can't encode"
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" character '{}' in position {}"
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.format(c, i))
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elif errors == "replace":
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r += REPLACE_CHAR
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elif errors == "ignore":
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continue
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else:
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raise ValueError("Unsupported error handling {}"
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.format(errors))
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return r, len(text)
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return encode
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def bacon_decode(code):
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def decode(text, errors="strict"):
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std0, stdn = [c for c in STD[0]], [c for c in STD[code]]
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spec0, specn = SPEC[0].split(), SPEC[code].split()
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mapping = {e: d for d, e in zip(std0 + spec0, stdn + specn)}
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r = ""
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for i, c in enumerate(ensure_str(text)):
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try:
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r += mapping[c]
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except KeyError:
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if errors == "strict":
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raise BaconDecodeError("'bacon' codec can't decode"
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" character '{}' in position {}"
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.format(c, i))
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elif errors == "replace":
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r += REPLACE_CHAR
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elif errors == "ignore":
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continue
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else:
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raise ValueError("Unsupported error handling {}"
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.format(errors))
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return r, len(text)
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return decode
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# note: the integer behind "bacon" is captured for sending to the
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# parametrizable encode and decode functions "bacon_**code"
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add("bacon", bacon_encode, bacon_decode, r"bacon(?:onian[-_]cipher)$")

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