#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2014 Thomas Voegtlin
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from datetime import datetime
import sys
import util
from util import profiler, print_error
from asn1tinydecoder import *
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])
class CertificateError(Exception):
pass
class X509(object):
def __init__(self, b):
self.bytes = bytearray(b)
der = str(b)
root = asn1_node_root(der)
cert = asn1_node_first_child(der, root)
# data for signature
self.data = asn1_get_all(der, cert)
# optional version field
if asn1_get_value(der, cert)[0] == chr(0xa0):
version = asn1_node_first_child(der, cert)
serial_number = asn1_node_next(der, version)
else:
serial_number = asn1_node_first_child(der, cert)
self.serial_number = bytestr_to_int(asn1_get_value_of_type(der, serial_number, 'INTEGER'))
# signature algorithm
sig_algo = asn1_node_next(der, serial_number)
ii = asn1_node_first_child(der, sig_algo)
self.sig_algo = decode_OID(asn1_get_value_of_type(der, ii, 'OBJECT IDENTIFIER'))
# issuer
issuer = asn1_node_next(der, sig_algo)
self.issuer = asn1_get_dict(der, issuer)
# validity
validity = asn1_node_next(der, issuer)
ii = asn1_node_first_child(der, validity)
self.notBefore = asn1_get_value_of_type(der, ii, 'UTCTime')
ii = asn1_node_next(der,ii)
self.notAfter = asn1_get_value_of_type(der, ii, 'UTCTime')
# subject
subject = asn1_node_next(der, validity)
self.subject = asn1_get_dict(der, subject)
subject_pki = asn1_node_next(der, subject)
public_key_algo = asn1_node_first_child(der, subject_pki)
ii = asn1_node_first_child(der, public_key_algo)
self.public_key_algo = decode_OID(asn1_get_value_of_type(der, ii, 'OBJECT IDENTIFIER'))
# pubkey modulus and exponent
subject_public_key = asn1_node_next(der, public_key_algo)
spk = asn1_get_value_of_type(der, subject_public_key, 'BIT STRING')
spk = bitstr_to_bytestr(spk)
r = asn1_node_root(spk)
modulus = asn1_node_first_child(spk, r)
exponent = asn1_node_next(spk, modulus)
rsa_n = asn1_get_value_of_type(spk, modulus, 'INTEGER')
rsa_e = asn1_get_value_of_type(spk, 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 = asn1_node_next(der, i)
d = asn1_get_dict(der, i)
for oid, value in d.items():
if oid == '2.5.29.19':
# Basic Constraints
self.CA = bool(value)
elif oid == '2.5.29.14':
# Subject Key Identifier
r = asn1_node_root(value)
value = asn1_get_value_of_type(value, r, 'OCTET STRING')
self.SKI = value.encode('hex')
elif oid == '2.5.29.35':
# Authority Key Identifier
self.AKI = asn1_get_sequence(value)[0].encode('hex')
else:
pass
# cert signature
cert_sig_algo = asn1_node_next(der, cert)
ii = asn1_node_first_child(der, cert_sig_algo)
self.cert_sig_algo = decode_OID(asn1_get_value_of_type(der, ii, 'OBJECT IDENTIFIER'))
cert_sig = asn1_node_next(der, cert_sig_algo)
self.signature = asn1_get_value(der, 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