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| 1 # Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
| 2 # Use of this source code is governed by a BSD-style license that can be | |
| 3 # found in the LICENSE file. | |
| 4 | |
| 5 # This file implements very minimal ASN.1, DER serialization. | |
| 6 | |
| 7 import types | |
| 8 | |
| 9 | |
| 10 def ToDER(obj): | |
| 11 '''ToDER converts the given object into DER encoding''' | |
| 12 if type(obj) == types.NoneType: | |
| 13 # None turns into NULL | |
| 14 return TagAndLength(5, 0) | |
| 15 if type(obj) == types.StringType: | |
| 16 # Strings are PRINTABLESTRING | |
| 17 return TagAndLength(19, len(obj)) + obj | |
| 18 if type(obj) == types.BooleanType: | |
| 19 val = "\x00" | |
| 20 if obj: | |
| 21 val = "\xff" | |
| 22 return TagAndLength(1, 1) + val | |
| 23 if type(obj) == types.IntType or type(obj) == types.LongType: | |
| 24 big_endian = [] | |
| 25 val = obj | |
| 26 while val != 0: | |
| 27 big_endian.append(val & 0xff) | |
| 28 val >>= 8 | |
| 29 | |
| 30 if len(big_endian) == 0 or big_endian[-1] >= 128: | |
| 31 big_endian.append(0) | |
| 32 | |
| 33 big_endian.reverse() | |
| 34 return TagAndLength(2, len(big_endian)) + ToBytes(big_endian) | |
| 35 | |
| 36 return obj.ToDER() | |
| 37 | |
| 38 | |
| 39 def ToBytes(array_of_bytes): | |
| 40 '''ToBytes converts the array of byte values into a binary string''' | |
| 41 return ''.join([chr(x) for x in array_of_bytes]) | |
| 42 | |
| 43 | |
| 44 def TagAndLength(tag, length): | |
| 45 der = [tag] | |
| 46 if length < 128: | |
| 47 der.append(length) | |
| 48 elif length < 256: | |
| 49 der.append(0x81) | |
| 50 der.append(length) | |
| 51 elif length < 65535: | |
| 52 der.append(0x82) | |
| 53 der.append(length >> 8) | |
| 54 der.append(length & 0xff) | |
| 55 else: | |
| 56 assert False | |
| 57 | |
| 58 return ToBytes(der) | |
| 59 | |
| 60 | |
| 61 class Raw(object): | |
| 62 '''Raw contains raw DER encoded bytes that are used verbatim''' | |
| 63 def __init__(self, der): | |
| 64 self.der = der | |
| 65 | |
| 66 def ToDER(self): | |
| 67 return self.der | |
| 68 | |
| 69 | |
| 70 class Explicit(object): | |
| 71 '''Explicit prepends an explicit tag''' | |
| 72 def __init__(self, tag, child): | |
| 73 self.tag = tag | |
| 74 self.child = child | |
| 75 | |
| 76 def ToDER(self): | |
| 77 der = ToDER(self.child) | |
| 78 tag = self.tag | |
| 79 tag |= 0x80 # content specific | |
| 80 tag |= 0x20 # complex | |
| 81 return TagAndLength(tag, len(der)) + der | |
| 82 | |
| 83 | |
| 84 class ENUMERATED(object): | |
| 85 def __init__(self, value): | |
| 86 self.value = value | |
| 87 | |
| 88 def ToDER(self): | |
| 89 return TagAndLength(10, 1) + chr(self.value) | |
| 90 | |
| 91 | |
| 92 class SEQUENCE(object): | |
| 93 def __init__(self, children): | |
| 94 self.children = children | |
| 95 | |
| 96 def ToDER(self): | |
| 97 der = ''.join([ToDER(x) for x in self.children]) | |
| 98 return TagAndLength(0x30, len(der)) + der | |
| 99 | |
| 100 | |
| 101 class SET(object): | |
| 102 def __init__(self, children): | |
| 103 self.children = children | |
| 104 | |
| 105 def ToDER(self): | |
| 106 der = ''.join([ToDER(x) for x in self.children]) | |
| 107 return TagAndLength(0x31, len(der)) + der | |
| 108 | |
| 109 | |
| 110 class OCTETSTRING(object): | |
| 111 def __init__(self, val): | |
| 112 self.val = val | |
| 113 | |
| 114 def ToDER(self): | |
| 115 return TagAndLength(4, len(self.val)) + self.val | |
| 116 | |
| 117 | |
| 118 class OID(object): | |
| 119 def __init__(self, parts): | |
| 120 self.parts = parts | |
| 121 | |
| 122 def ToDER(self): | |
| 123 if len(self.parts) < 2 or self.parts[0] > 6 or self.parts[1] >= 40: | |
| 124 assert False | |
| 125 | |
| 126 der = [self.parts[0]*40 + self.parts[1]] | |
| 127 for x in self.parts[2:]: | |
| 128 if x == 0: | |
| 129 der.append(0) | |
| 130 else: | |
| 131 octets = [] | |
| 132 while x != 0: | |
| 133 v = x & 0x7f | |
| 134 if len(octets) > 0: | |
| 135 v |= 0x80 | |
| 136 octets.append(v) | |
| 137 x >>= 7 | |
| 138 octets.reverse() | |
| 139 der = der + octets | |
| 140 | |
| 141 return TagAndLength(6, len(der)) + ToBytes(der) | |
| 142 | |
| 143 | |
| 144 class UTCTime(object): | |
| 145 def __init__(self, time_str): | |
| 146 self.time_str = time_str | |
| 147 | |
| 148 def ToDER(self): | |
| 149 return TagAndLength(23, len(self.time_str)) + self.time_str | |
| 150 | |
| 151 | |
| 152 class GeneralizedTime(object): | |
| 153 def __init__(self, time_str): | |
| 154 self.time_str = time_str | |
| 155 | |
| 156 def ToDER(self): | |
| 157 return TagAndLength(24, len(self.time_str)) + self.time_str | |
| 158 | |
| 159 | |
| 160 class BitString(object): | |
| 161 def __init__(self, bits): | |
| 162 self.bits = bits | |
| 163 | |
| 164 def ToDER(self): | |
| 165 return TagAndLength(3, 1 + len(self.bits)) + "\x00" + self.bits | |
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