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