file reorganization with top-level module
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341
electrum/x509.py
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341
electrum/x509.py
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#!/usr/bin/env python
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#
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# Electrum - lightweight Bitcoin client
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# Copyright (C) 2014 Thomas Voegtlin
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#
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# Permission is hereby granted, free of charge, to any person
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# obtaining a copy of this software and associated documentation files
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# (the "Software"), to deal in the Software without restriction,
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# including without limitation the rights to use, copy, modify, merge,
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# publish, distribute, sublicense, and/or sell copies of the Software,
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# and to permit persons to whom the Software is furnished to do so,
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# subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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from . import util
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from .util import profiler, bh2u
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import ecdsa
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import hashlib
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# algo OIDs
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ALGO_RSA_SHA1 = '1.2.840.113549.1.1.5'
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ALGO_RSA_SHA256 = '1.2.840.113549.1.1.11'
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ALGO_RSA_SHA384 = '1.2.840.113549.1.1.12'
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ALGO_RSA_SHA512 = '1.2.840.113549.1.1.13'
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ALGO_ECDSA_SHA256 = '1.2.840.10045.4.3.2'
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# prefixes, see http://stackoverflow.com/questions/3713774/c-sharp-how-to-calculate-asn-1-der-encoding-of-a-particular-hash-algorithm
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PREFIX_RSA_SHA256 = bytearray(
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[0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20])
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PREFIX_RSA_SHA384 = bytearray(
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[0x30, 0x41, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02, 0x05, 0x00, 0x04, 0x30])
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PREFIX_RSA_SHA512 = bytearray(
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[0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, 0x05, 0x00, 0x04, 0x40])
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# types used in ASN1 structured data
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ASN1_TYPES = {
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'BOOLEAN' : 0x01,
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'INTEGER' : 0x02,
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'BIT STRING' : 0x03,
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'OCTET STRING' : 0x04,
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'NULL' : 0x05,
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'OBJECT IDENTIFIER': 0x06,
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'SEQUENCE' : 0x70,
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'SET' : 0x71,
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'PrintableString' : 0x13,
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'IA5String' : 0x16,
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'UTCTime' : 0x17,
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'GeneralizedTime' : 0x18,
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'ENUMERATED' : 0x0A,
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'UTF8String' : 0x0C,
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}
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class CertificateError(Exception):
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pass
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# helper functions
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def bitstr_to_bytestr(s):
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if s[0] != 0x00:
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raise TypeError('no padding')
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return s[1:]
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def bytestr_to_int(s):
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i = 0
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for char in s:
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i <<= 8
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i |= char
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return i
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def decode_OID(s):
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r = []
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r.append(s[0] // 40)
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r.append(s[0] % 40)
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k = 0
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for i in s[1:]:
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if i < 128:
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r.append(i + 128 * k)
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k = 0
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else:
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k = (i - 128) + 128 * k
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return '.'.join(map(str, r))
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def encode_OID(oid):
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x = [int(i) for i in oid.split('.')]
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s = chr(x[0] * 40 + x[1])
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for i in x[2:]:
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ss = chr(i % 128)
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while i > 128:
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i //= 128
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ss = chr(128 + i % 128) + ss
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s += ss
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return s
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class ASN1_Node(bytes):
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def get_node(self, ix):
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# return index of first byte, first content byte and last byte.
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first = self[ix + 1]
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if (first & 0x80) == 0:
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length = first
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ixf = ix + 2
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ixl = ixf + length - 1
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else:
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lengthbytes = first & 0x7F
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length = bytestr_to_int(self[ix + 2:ix + 2 + lengthbytes])
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ixf = ix + 2 + lengthbytes
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ixl = ixf + length - 1
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return ix, ixf, ixl
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def root(self):
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return self.get_node(0)
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def next_node(self, node):
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ixs, ixf, ixl = node
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return self.get_node(ixl + 1)
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def first_child(self, node):
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ixs, ixf, ixl = node
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if self[ixs] & 0x20 != 0x20:
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raise TypeError('Can only open constructed types.', hex(self[ixs]))
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return self.get_node(ixf)
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def is_child_of(node1, node2):
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ixs, ixf, ixl = node1
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jxs, jxf, jxl = node2
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return ((ixf <= jxs) and (jxl <= ixl)) or ((jxf <= ixs) and (ixl <= jxl))
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def get_all(self, node):
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# return type + length + value
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ixs, ixf, ixl = node
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return self[ixs:ixl + 1]
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def get_value_of_type(self, node, asn1_type):
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# verify type byte and return content
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ixs, ixf, ixl = node
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if ASN1_TYPES[asn1_type] != self[ixs]:
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raise TypeError('Wrong type:', hex(self[ixs]), hex(ASN1_TYPES[asn1_type]))
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return self[ixf:ixl + 1]
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def get_value(self, node):
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ixs, ixf, ixl = node
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return self[ixf:ixl + 1]
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def get_children(self, node):
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nodes = []
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ii = self.first_child(node)
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nodes.append(ii)
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while ii[2] < node[2]:
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ii = self.next_node(ii)
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nodes.append(ii)
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return nodes
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def get_sequence(self):
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return list(map(lambda j: self.get_value(j), self.get_children(self.root())))
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def get_dict(self, node):
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p = {}
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for ii in self.get_children(node):
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for iii in self.get_children(ii):
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iiii = self.first_child(iii)
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oid = decode_OID(self.get_value_of_type(iiii, 'OBJECT IDENTIFIER'))
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iiii = self.next_node(iiii)
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value = self.get_value(iiii)
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p[oid] = value
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return p
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class X509(object):
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def __init__(self, b):
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self.bytes = bytearray(b)
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der = ASN1_Node(b)
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root = der.root()
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cert = der.first_child(root)
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# data for signature
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self.data = der.get_all(cert)
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# optional version field
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if der.get_value(cert)[0] == 0xa0:
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version = der.first_child(cert)
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serial_number = der.next_node(version)
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else:
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serial_number = der.first_child(cert)
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self.serial_number = bytestr_to_int(der.get_value_of_type(serial_number, 'INTEGER'))
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# signature algorithm
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sig_algo = der.next_node(serial_number)
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ii = der.first_child(sig_algo)
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self.sig_algo = decode_OID(der.get_value_of_type(ii, 'OBJECT IDENTIFIER'))
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# issuer
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issuer = der.next_node(sig_algo)
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self.issuer = der.get_dict(issuer)
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# validity
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validity = der.next_node(issuer)
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ii = der.first_child(validity)
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try:
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self.notBefore = der.get_value_of_type(ii, 'UTCTime')
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except TypeError:
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self.notBefore = der.get_value_of_type(ii, 'GeneralizedTime')[2:] # strip year
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ii = der.next_node(ii)
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try:
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self.notAfter = der.get_value_of_type(ii, 'UTCTime')
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except TypeError:
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self.notAfter = der.get_value_of_type(ii, 'GeneralizedTime')[2:] # strip year
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# subject
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subject = der.next_node(validity)
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self.subject = der.get_dict(subject)
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subject_pki = der.next_node(subject)
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public_key_algo = der.first_child(subject_pki)
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ii = der.first_child(public_key_algo)
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self.public_key_algo = decode_OID(der.get_value_of_type(ii, 'OBJECT IDENTIFIER'))
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if self.public_key_algo != '1.2.840.10045.2.1': # for non EC public key
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# pubkey modulus and exponent
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subject_public_key = der.next_node(public_key_algo)
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spk = der.get_value_of_type(subject_public_key, 'BIT STRING')
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spk = ASN1_Node(bitstr_to_bytestr(spk))
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r = spk.root()
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modulus = spk.first_child(r)
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exponent = spk.next_node(modulus)
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rsa_n = spk.get_value_of_type(modulus, 'INTEGER')
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rsa_e = spk.get_value_of_type(exponent, 'INTEGER')
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self.modulus = ecdsa.util.string_to_number(rsa_n)
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self.exponent = ecdsa.util.string_to_number(rsa_e)
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else:
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subject_public_key = der.next_node(public_key_algo)
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spk = der.get_value_of_type(subject_public_key, 'BIT STRING')
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self.ec_public_key = spk
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# extensions
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self.CA = False
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self.AKI = None
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self.SKI = None
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i = subject_pki
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while i[2] < cert[2]:
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i = der.next_node(i)
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d = der.get_dict(i)
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for oid, value in d.items():
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value = ASN1_Node(value)
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if oid == '2.5.29.19':
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# Basic Constraints
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self.CA = bool(value)
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elif oid == '2.5.29.14':
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# Subject Key Identifier
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r = value.root()
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value = value.get_value_of_type(r, 'OCTET STRING')
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self.SKI = bh2u(value)
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elif oid == '2.5.29.35':
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# Authority Key Identifier
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self.AKI = bh2u(value.get_sequence()[0])
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else:
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pass
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# cert signature
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cert_sig_algo = der.next_node(cert)
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ii = der.first_child(cert_sig_algo)
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self.cert_sig_algo = decode_OID(der.get_value_of_type(ii, 'OBJECT IDENTIFIER'))
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cert_sig = der.next_node(cert_sig_algo)
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self.signature = der.get_value(cert_sig)[1:]
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def get_keyID(self):
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# http://security.stackexchange.com/questions/72077/validating-an-ssl-certificate-chain-according-to-rfc-5280-am-i-understanding-th
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return self.SKI if self.SKI else repr(self.subject)
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def get_issuer_keyID(self):
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return self.AKI if self.AKI else repr(self.issuer)
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def get_common_name(self):
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return self.subject.get('2.5.4.3', b'unknown').decode()
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def get_signature(self):
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return self.cert_sig_algo, self.signature, self.data
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def check_ca(self):
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return self.CA
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def check_date(self):
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import time
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now = time.time()
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TIMESTAMP_FMT = '%y%m%d%H%M%SZ'
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not_before = time.mktime(time.strptime(self.notBefore.decode('ascii'), TIMESTAMP_FMT))
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not_after = time.mktime(time.strptime(self.notAfter.decode('ascii'), TIMESTAMP_FMT))
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if not_before > now:
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raise CertificateError('Certificate has not entered its valid date range. (%s)' % self.get_common_name())
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if not_after <= now:
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raise CertificateError('Certificate has expired. (%s)' % self.get_common_name())
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def getFingerprint(self):
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return hashlib.sha1(self.bytes).digest()
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@profiler
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def load_certificates(ca_path):
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from . import pem
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ca_list = {}
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ca_keyID = {}
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# ca_path = '/tmp/tmp.txt'
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with open(ca_path, 'r', encoding='utf-8') as f:
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s = f.read()
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bList = pem.dePemList(s, "CERTIFICATE")
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for b in bList:
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try:
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x = X509(b)
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x.check_date()
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except BaseException as e:
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# with open('/tmp/tmp.txt', 'w') as f:
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# f.write(pem.pem(b, 'CERTIFICATE').decode('ascii'))
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util.print_error("cert error:", e)
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continue
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fp = x.getFingerprint()
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ca_list[fp] = x
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ca_keyID[x.get_keyID()] = fp
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return ca_list, ca_keyID
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if __name__ == "__main__":
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import requests
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util.set_verbosity(True)
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ca_path = requests.certs.where()
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ca_list, ca_keyID = load_certificates(ca_path)
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