1 | ''' |
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2 | A collection of tools to assist in analyzing encrypted blobs of data |
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3 | |
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4 | Copyright (C) 2011-2013 Virtual Security Research, LLC |
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5 | Author: Timothy D. Morgan, Jason A. Donenfeld |
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6 | |
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7 | This program is free software: you can redistribute it and/or modify |
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8 | it under the terms of the GNU Lesser General Public License, version 3, |
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9 | as published by the Free Software Foundation. |
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10 | |
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11 | This program is distributed in the hope that it will be useful, |
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12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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14 | GNU General Public License for more details. |
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15 | |
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16 | You should have received a copy of the GNU General Public License |
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17 | along with this program. If not, see <http://www.gnu.org/licenses/>. |
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18 | ''' |
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19 | |
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20 | import sys |
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21 | import base64 |
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22 | import binascii |
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23 | import traceback |
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24 | import fractions |
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25 | import operator |
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26 | import functools |
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27 | from . import buffertools |
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28 | |
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29 | |
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30 | # urllib.parse's functions are not well suited for encoding/decoding |
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31 | # bytes or managing encoded case |
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32 | def _percentEncode(binary, plus=False, upper=True): |
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33 | fmt = "%%%.2x" |
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34 | if upper: |
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35 | fmt = "%%%.2X" |
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36 | |
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37 | ret_val = bytearray(b'') |
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38 | for c in binary: |
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39 | if c not in b'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789': |
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40 | ret_val.extend((fmt % c).encode('ascii')) |
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41 | elif plus and (c == 20): |
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42 | ret_val.extend(b'+') |
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43 | else: |
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44 | ret_val.append(c) |
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45 | |
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46 | return ret_val |
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47 | |
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48 | |
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49 | def _percentDecode(binary, plus=False): |
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50 | if plus: |
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51 | binary = binary.replace(b'+', b' ') |
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52 | if binary == b'': |
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53 | return b'' |
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54 | chunks = binary.split(b'%') |
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55 | |
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56 | ret_val = chunks[0] |
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57 | for chunk in chunks[1:]: |
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58 | if len(chunk) < 2: |
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59 | return None |
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60 | try: |
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61 | ret_val += bytes([int(chunk[0:2], 16)]) + chunk[2:] |
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62 | except: |
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63 | #traceback.print_exc() |
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64 | #print(repr(chunk), repr(binary)) |
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65 | return None |
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66 | |
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67 | return ret_val |
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68 | |
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69 | |
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70 | # abstract class |
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71 | class DataEncoding(object): |
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72 | charset = frozenset(b'') |
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73 | extraneous_chars = b'' |
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74 | dialect = None |
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75 | name = None |
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76 | priority = None |
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77 | |
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78 | def __init__(self, dialect=''): |
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79 | self.dialect = dialect |
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80 | |
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81 | def isExample(self, blob): |
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82 | sblob = frozenset(blob) |
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83 | if self.charset != None and not sblob.issubset(self.charset): |
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84 | return False |
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85 | return self.extraTests(blob) |
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86 | |
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87 | def extraTests(self, blob): |
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88 | """May return True, False, or None, for is an example, isn't an |
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89 | example, or unknown, respectively. |
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90 | |
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91 | """ |
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92 | return True |
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93 | |
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94 | def decode(self, blob): |
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95 | return None |
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96 | |
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97 | def encode(self, blob): |
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98 | return None |
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99 | |
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100 | |
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101 | class base64Encoding(DataEncoding): |
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102 | name = 'base64' |
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103 | def __init__(self, dialect='rfc3548'): |
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104 | super(base64Encoding, self).__init__(dialect) |
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105 | if dialect.startswith('rfc3548'): |
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106 | self.c62 = b'+' |
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107 | self.c63 = b'/' |
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108 | self.pad = b'=' |
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109 | elif dialect.startswith('filename'): |
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110 | self.c62 = b'+' |
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111 | self.c63 = b'-' |
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112 | self.pad = b'=' |
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113 | elif dialect.startswith('url1'): |
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114 | self.c62 = b'-' |
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115 | self.c63 = b'_' |
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116 | self.pad = b'=' |
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117 | elif dialect.startswith('url2'): |
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118 | self.c62 = b'-' |
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119 | self.c63 = b'_' |
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120 | self.pad = b'.' |
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121 | elif dialect.startswith('url3'): |
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122 | self.c62 = b'_' |
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123 | self.c63 = b'-' |
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124 | self.pad = b'.' |
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125 | elif dialect.startswith('url4'): |
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126 | self.c62 = b'-' |
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127 | self.c63 = b'_' |
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128 | self.pad = b'!' |
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129 | elif dialect.startswith('url5'): |
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130 | self.c62 = b'+' |
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131 | self.c63 = b'/' |
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132 | self.pad = b'$' |
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133 | elif dialect.startswith('url6'): |
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134 | self.c62 = b'*' |
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135 | self.c63 = b'/' |
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136 | self.pad = b'=' |
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137 | elif dialect.startswith('otkurl'): |
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138 | self.c62 = b'-' |
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139 | self.c63 = b'_' |
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140 | self.pad = b'*' |
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141 | elif dialect.startswith('xmlnmtoken'): |
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142 | self.c62 = b'.' |
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143 | self.c63 = b'-' |
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144 | self.pad = b'=' |
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145 | elif dialect.startswith('xmlname'): |
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146 | self.c62 = b'_' |
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147 | self.c63 = b':' |
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148 | self.pad = b'=' |
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149 | |
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150 | if 'newline' in dialect: |
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151 | self.extraneous_chars = b'\r\n' |
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152 | |
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153 | self.charset = frozenset(b'ABCDEFGHIJKLMNOPQRSTUVWXYZ' |
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154 | +b'abcdefghijklmnopqrstuvwxyz0123456789' |
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155 | +self.c62+self.c63+self.pad+self.extraneous_chars) |
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156 | |
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157 | def _guessPadLength(self, nopad_len): |
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158 | length = ((4 - nopad_len % 4) % 4) |
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159 | if length != 3: |
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160 | return length |
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161 | return None |
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162 | |
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163 | def extraTests(self, blob): |
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164 | for c in self.extraneous_chars: |
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165 | blob = blob.replace(bytes([c]), b'') |
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166 | |
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167 | if self.dialect.endswith('intpad'): |
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168 | if blob[-1] not in b'012': |
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169 | return False |
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170 | nopad = blob[:-1] |
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171 | padlen = blob[-1] - 48 # see the ascii table |
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172 | else: |
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173 | nopad = blob.rstrip(self.pad) |
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174 | padlen = len(blob) - len(nopad) |
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175 | |
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176 | # what the pad length ought to be |
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177 | padlen_guess = self._guessPadLength(len(nopad)) |
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178 | if padlen_guess == None: |
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179 | return False |
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180 | |
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181 | # we don't accept bad pads, only missing pads |
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182 | if self.dialect.endswith('nopad'): |
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183 | return self.pad not in blob |
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184 | |
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185 | # pad must not appear in the middle of the |
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186 | # string and must be the correct length at the end |
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187 | return (self.pad not in nopad) and (padlen == padlen_guess) |
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188 | |
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189 | def decode(self, blob): |
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190 | for c in self.extraneous_chars: |
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191 | blob = blob.replace(bytes(c), b'') |
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192 | |
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193 | if self.dialect.endswith('intpad'): |
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194 | padlen = blob[-1] - 48 # see the ascii table |
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195 | padlen_guess = self._guessPadLength(len(blob[:-1])) |
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196 | if padlen != padlen_guess: |
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197 | raise Exception("Invalid length for int-padded base64 string. (%d != %d)" |
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198 | % (padlen, padlen_guess)) |
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199 | |
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200 | blob = blob[:-1] + (self.pad*padlen) |
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201 | |
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202 | if self.dialect.endswith('nopad'): |
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203 | if self.pad in blob: |
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204 | raise Exception("Unpadded base64 string contains pad character") |
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205 | |
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206 | padlen = self._guessPadLength(len(blob)) |
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207 | if padlen == None: |
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208 | raise Exception("Invalid length for unpadded base64 string.") |
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209 | |
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210 | blob = blob+(self.pad*padlen) |
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211 | |
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212 | if not self.dialect.startswith('rfc3548'): |
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213 | table = bytes.maketrans(self.c62+self.c63+self.pad, b'+/=') |
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214 | blob = blob.translate(table) |
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215 | |
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216 | return base64.standard_b64decode(blob) |
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217 | |
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218 | |
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219 | def encode(self, blob): |
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220 | ret_val = base64.standard_b64encode(blob) |
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221 | |
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222 | if not self.dialect.startswith('rfc3548'): |
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223 | table = bytes.maketrans(b'+/=', self.c62+self.c63+self.pad) |
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224 | ret_val = ret_val.translate(table) |
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225 | |
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226 | if ret_val != None and self.dialect.endswith('nopad'): |
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227 | ret_val = ret_val.rstrip(self.pad) |
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228 | |
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229 | if ret_val != None and self.dialect.endswith('intpad'): |
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230 | stripped = ret_val.rstrip(self.pad) |
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231 | ret_val = stripped + ("%d" % (len(ret_val) - len(stripped))).encode('utf-8') |
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232 | |
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233 | return ret_val |
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234 | |
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235 | |
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236 | class base32Encoding(DataEncoding): |
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237 | name = 'base32' |
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238 | def __init__(self, dialect='rfc3548upper'): |
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239 | super(base32Encoding, self).__init__(dialect) |
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240 | if dialect.startswith('rfc3548upper'): |
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241 | self.pad = b'=' |
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242 | self.charset = frozenset(b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'+self.pad) |
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243 | |
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244 | elif dialect.startswith('rfc3548lower'): |
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245 | self.pad = b'=' |
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246 | self.charset = frozenset(b'abcdefghijklmnopqrstuvwxyz234567'+self.pad) |
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247 | |
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248 | def _guessPadLength(self, nopad_len): |
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249 | pad_lengths = {0:0, 7:1, 5:3, 4:4, 2:6} |
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250 | return pad_lengths.get(nopad_len%8, None) |
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251 | |
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252 | def extraTests(self, blob): |
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253 | nopad = blob.rstrip(self.pad) |
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254 | padlen_guess = self._guessPadLength(len(nopad)) |
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255 | if padlen_guess == None: |
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256 | return False |
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257 | |
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258 | # we don't accept bad pads, only missing pads |
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259 | if self.dialect.endswith('nopad'): |
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260 | return self.pad not in blob |
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261 | |
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262 | # pad must not appear in the middle of the |
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263 | # string and must be the correct length at the end |
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264 | return (self.pad not in nopad) and (len(blob) == len(nopad)+padlen_guess) |
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265 | |
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266 | |
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267 | def decode(self, blob): |
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268 | if self.dialect.endswith('nopad'): |
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269 | if self.pad in blob: |
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270 | raise Exception("Unpadded base32 string contains pad character") |
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271 | |
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272 | padlen = self._guessPadLength(len(blob)) |
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273 | if padlen == None: |
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274 | raise Exception("Invalid length for unpadded base64 string.") |
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275 | |
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276 | blob = blob+(self.pad*padlen) |
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277 | |
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278 | return base64.b32decode(blob.upper()) |
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279 | |
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280 | |
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281 | def encode(self, blob): |
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282 | ret_val = base64.b32encode(blob) |
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283 | |
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284 | if ret_val != None and self.dialect.endswith('nopad'): |
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285 | ret_val = ret_val.rstrip(self.pad) |
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286 | |
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287 | if 'lower' in self.dialect: |
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288 | ret_val = ret_val.lower() |
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289 | else: |
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290 | ret_val = ret_val.upper() |
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291 | |
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292 | return ret_val |
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293 | |
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294 | |
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295 | class hexEncoding(DataEncoding): |
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296 | name = 'hex' |
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297 | def __init__(self, dialect='mixed'): |
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298 | super(hexEncoding, self).__init__(dialect) |
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299 | if 'mixed' in dialect: |
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300 | self.charset = frozenset(b'ABCDEFabcdef0123456789') |
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301 | elif 'upper' in dialect: |
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302 | self.charset = frozenset(b'ABCDEF0123456789') |
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303 | elif 'lower' in dialect: |
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304 | self.charset = frozenset(b'abcdef0123456789') |
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305 | |
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306 | |
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307 | def extraTests(self, blob): |
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308 | return (len(blob) % 2 == 0) |
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309 | |
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310 | def decode(self, blob): |
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311 | return binascii.a2b_hex(blob) |
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312 | |
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313 | def encode(self, blob): |
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314 | if 'upper' in self.dialect: |
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315 | return binascii.b2a_hex(blob).upper() |
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316 | if 'lower' in self.dialect: |
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317 | return binascii.b2a_hex(blob).lower() |
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318 | else: |
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319 | return binascii.b2a_hex(blob) |
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320 | |
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321 | |
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322 | class percentEncoding(DataEncoding): |
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323 | name = 'percent' |
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324 | def __init__(self, dialect='mixed'): |
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325 | super(percentEncoding, self).__init__(dialect) |
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326 | self.charset = None |
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327 | if 'mixed' in dialect: |
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328 | self.hexchars = frozenset(b'ABCDEFabcdef0123456789') |
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329 | elif 'upper' in dialect: |
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330 | self.hexchars = frozenset(b'ABCDEF0123456789') |
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331 | elif 'lower' in dialect: |
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332 | self.hexchars = frozenset(b'abcdef0123456789') |
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333 | |
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334 | def extraTests(self, blob): |
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335 | chunks = blob.split(b'%') |
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336 | if len(chunks) < 2: |
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337 | return None |
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338 | for c in chunks[1:]: |
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339 | if len(c) < 2: |
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340 | return False |
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341 | if (c[0] not in self.hexchars) or (c[1] not in self.hexchars): |
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342 | return False |
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343 | return True |
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344 | |
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345 | def decode(self, blob): |
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346 | plus = False |
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347 | if 'plus' in self.dialect: |
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348 | plus = True |
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349 | return _percentDecode(blob, plus=plus) |
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350 | |
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351 | def encode(self, blob): |
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352 | upper = True |
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353 | plus = False |
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354 | if 'plus' in self.dialect: |
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355 | plus = True |
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356 | if 'lower' in self.dialect: |
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357 | upper = False |
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358 | |
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359 | return _percentEncode(blob, plus=plus, upper=upper) |
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360 | |
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361 | # XXX: need a better way to organize these with the possible combinations of dialects, padding, etc |
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362 | # for instance, can we have rfc3548-newline-nopad ? |
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363 | priorities = [ |
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364 | (hexEncoding, 'upper', 100), |
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365 | (hexEncoding, 'lower', 101), |
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366 | (hexEncoding, 'mixed', 102), |
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367 | (base32Encoding, 'rfc3548upper', 150), |
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368 | (base32Encoding, 'rfc3548lower', 151), |
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369 | (base32Encoding, 'rfc3548upper-nopad', 160), |
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370 | (base32Encoding, 'rfc3548lower-nopad', 161), |
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371 | (base64Encoding, 'rfc3548', 200), |
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372 | (base64Encoding, 'rfc3548-nopad', 201), |
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373 | (base64Encoding, 'rfc3548-newline', 202), |
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374 | (base64Encoding, 'rfc3548-intpad', 203), |
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375 | (base64Encoding, 'filename', 210), |
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376 | (base64Encoding, 'filename-nopad', 211), |
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377 | (base64Encoding, 'filename-intpad', 212), |
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378 | (base64Encoding, 'url1', 230), |
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379 | (base64Encoding, 'url1-nopad', 231), |
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380 | (base64Encoding, 'url1-intpad', 232), |
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381 | (base64Encoding, 'otkurl', 235), |
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382 | (base64Encoding, 'otkurl-nopad', 236), |
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383 | (base64Encoding, 'otkurl-intpad', 237), |
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384 | (base64Encoding, 'url2', 240), |
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385 | (base64Encoding, 'url2-nopad', 241), |
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386 | (base64Encoding, 'url2-intpad', 242), |
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387 | (base64Encoding, 'url3', 250), |
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388 | (base64Encoding, 'url3-nopad', 251), |
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389 | (base64Encoding, 'url3-intpad', 252), |
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390 | (base64Encoding, 'url4', 260), |
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391 | (base64Encoding, 'url4-nopad', 261), |
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392 | (base64Encoding, 'url4-intpad', 262), |
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393 | (base64Encoding, 'url5', 265), |
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394 | (base64Encoding, 'url5-nopad', 266), |
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395 | (base64Encoding, 'url5-intpad', 267), |
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396 | (base64Encoding, 'url6', 267), |
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397 | (base64Encoding, 'url6-nopad', 268), |
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398 | (base64Encoding, 'url6-intpad', 269), |
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399 | (base64Encoding, 'xmlnmtoken', 270), |
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400 | (base64Encoding, 'xmlnmtoken-nopad', 271), |
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401 | (base64Encoding, 'xmlnmtoken-intpad', 272), |
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402 | (base64Encoding, 'xmlname', 280), |
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403 | (base64Encoding, 'xmlname-nopad', 281), |
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404 | (base64Encoding, 'xmlname-intpad', 282), |
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405 | (percentEncoding, 'upper-plus', 400), |
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406 | (percentEncoding, 'upper', 401), |
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407 | (percentEncoding, 'lower-plus', 410), |
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408 | (percentEncoding, 'lower', 411), |
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409 | (percentEncoding, 'mixed-plus', 420), |
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410 | (percentEncoding, 'mixed', 421), |
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411 | ] |
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412 | |
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413 | encodings = {} |
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414 | for enc,d,p in priorities: |
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415 | e = enc(d) |
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416 | e.priority = p |
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417 | encodings["%s/%s" % (enc.name, d)] = e |
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418 | |
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419 | |
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420 | def supportedEncodings(): |
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421 | e = list(encodings.keys()) |
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422 | e.sort() |
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423 | return e |
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424 | |
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425 | |
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426 | def possibleEncodings(blob): |
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427 | likely = set() |
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428 | possible = set() |
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429 | for name,encoding in encodings.items(): |
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430 | result = encoding.isExample(blob) |
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431 | if result == True: |
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432 | likely.add(name) |
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433 | elif result == None: |
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434 | possible.add(name) |
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435 | return likely,possible |
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436 | |
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437 | |
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438 | def encodingIntersection(blobs): |
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439 | ret_val = set(encodings.keys()) |
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440 | p = set(encodings.keys()) |
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441 | for b in blobs: |
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442 | likely,possible = possibleEncodings(b) |
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443 | ret_val &= likely | possible |
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444 | p &= possible |
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445 | return ret_val - p |
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446 | |
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447 | |
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448 | def bestEncoding(encs): |
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449 | priority = 999999999 |
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450 | best = None |
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451 | for e in encs: |
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452 | if encodings[e].priority < priority: |
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453 | best = e |
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454 | priority = encodings[e].priority |
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455 | return best |
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456 | |
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457 | |
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458 | def decode(encoding, blob): |
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459 | """Given an encoding name and a blob, decodes the blob and returns it. |
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460 | |
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461 | encoding -- A string representation of the encoding and dialect. |
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462 | For a list of valid encoding names, run: |
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463 | bletchley-analyze -e ? |
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464 | |
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465 | blob -- A bytes or bytearray object to be decoded. If a string |
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466 | is provided instead, it will be converted to a bytes |
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467 | object using 'utf-8'. |
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468 | |
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469 | Returns a bytes object containing the decoded representation of |
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470 | blob. Will throw various types of exceptions if a problem is |
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471 | encountered. |
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472 | """ |
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473 | if isinstance(blob, str): |
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474 | blob = blob.encode('utf-8') |
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475 | return encodings[encoding].decode(blob) |
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476 | |
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477 | def encode(encoding, blob): |
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478 | """Given an encoding name and a blob, encodes the blob and returns it. |
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479 | |
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480 | encoding -- A string representation of the encoding and dialect. |
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481 | For a list of valid encoding names, run: |
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482 | bletchley-analyze -e ? |
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483 | |
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484 | blob -- A bytes or bytearray object to be encoded. |
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485 | |
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486 | Returns a bytes object containing the encoded representation of |
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487 | blob. Will throw various types of exceptions if a problem is |
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488 | encountered.""" |
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489 | return encodings[encoding].encode(blob) |
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490 | |
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491 | |
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492 | def decodeAll(encoding, blobs): |
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493 | return [encodings[encoding].decode(b) for b in blobs] |
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494 | |
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495 | |
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496 | def encodeAll(encoding, blobs): |
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497 | return [encodings[encoding].encode(b) for b in blobs] |
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498 | |
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499 | |
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500 | def decodeChain(decoding_chain, blob): |
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501 | """Given a sequence of encoding names (decoding_chain) and a blob, |
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502 | decodes the blob once for each element of the decoding_chain. For |
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503 | instance, if the decoding_chain were |
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504 | ['percent/lower', 'base64/rfc3548'] |
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505 | then blob would first be decoded as 'percent/lower', followed by |
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506 | 'base64/rfc3548'. |
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507 | |
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508 | decoding_chain -- A sequence (list,tuple,...) of string |
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509 | representations of the encoding and dialect. For a |
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510 | list of valid encoding names, run: |
---|
511 | bletchley-analyze -e ? |
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512 | |
---|
513 | blob -- A bytes or bytearray object to be decoded. If a string |
---|
514 | is provided instead, it will be converted to a bytes |
---|
515 | object using 'utf-8'. |
---|
516 | |
---|
517 | Returns a bytes object containing the decoded representation of |
---|
518 | blob. Will throw various types of exceptions if a problem is |
---|
519 | encountered. |
---|
520 | """ |
---|
521 | for decoding in decoding_chain: |
---|
522 | blob = decode(decoding, blob) |
---|
523 | return blob |
---|
524 | |
---|
525 | |
---|
526 | def encodeChain(encoding_chain, blob): |
---|
527 | """Given a sequence of encoding names (encoding_chain) and a blob, |
---|
528 | encodes the blob once for each element of the encoding_chain. For |
---|
529 | instance, if the encoding_chain were |
---|
530 | ['base64/rfc3548', 'percent/lower',] |
---|
531 | then blob would first be encoded as 'base64/rfc3548', followed by |
---|
532 | 'percent/lower'. |
---|
533 | |
---|
534 | encoding_chain -- A sequence (list,tuple,...) of string |
---|
535 | representations of the encoding and dialect. For a |
---|
536 | list of valid encoding names, run: |
---|
537 | bletchley-analyze -e ? |
---|
538 | |
---|
539 | blob -- A bytes or bytearray object to be encoded. |
---|
540 | |
---|
541 | Returns a bytes object containing the encoded representation of |
---|
542 | blob. Will throw various types of exceptions if a problem is |
---|
543 | encountered. |
---|
544 | """ |
---|
545 | for encoding in encoding_chain: |
---|
546 | blob = encode(encoding, blob) |
---|
547 | return blob |
---|
548 | |
---|
549 | |
---|
550 | def getLengths(s): |
---|
551 | lengths = set() |
---|
552 | for bin in s: |
---|
553 | lengths.add(len(bin)) |
---|
554 | lengths = list(lengths) |
---|
555 | lengths.sort() |
---|
556 | return lengths |
---|
557 | |
---|
558 | |
---|
559 | def maxBlockSize(blob_lengths): |
---|
560 | divisor = 0 |
---|
561 | for bl in blob_lengths: |
---|
562 | divisor = fractions.gcd(divisor, bl) |
---|
563 | |
---|
564 | return divisor |
---|
565 | |
---|
566 | |
---|
567 | allTrue = functools.partial(functools.reduce, (lambda x,y: x and y)) |
---|
568 | |
---|
569 | def checkCommonBlocksizes(lengths): |
---|
570 | common_block_sizes = (8,16,20) |
---|
571 | ret_val = [] |
---|
572 | for cbs in common_block_sizes: |
---|
573 | gcdIsCBS = (lambda x: fractions.gcd(x,cbs)==cbs) |
---|
574 | if allTrue(map(gcdIsCBS, lengths)): |
---|
575 | ret_val.append(cbs) |
---|
576 | return ret_val |
---|
577 | |
---|
578 | |
---|
579 | def int2binary(x, bits=8): |
---|
580 | """ |
---|
581 | Integer to binary |
---|
582 | Count is number of bits |
---|
583 | """ |
---|
584 | return "".join(map(lambda y:str((x>>y)&1), range(bits-1, -1, -1))) |
---|