summaryrefslogtreecommitdiff
path: root/tools/certtools.py
blob: cbb4ff73a3d8f7de82252924b8089ecd10d4c6f1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
# Copyright (c) 2014, NORDUnet A/S.
# See LICENSE for licensing information.

import subprocess
import json
import base64
import urllib
import urllib2
import struct
import sys
import hashlib
import ecdsa
import datetime

publickeys = {
    "https://ct.googleapis.com/pilot/":
    "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEfahLEimAoz2t01p3uMziiLOl/fHTD"
    "M0YDOhBRuiBARsV4UvxG2LdNgoIGLrtCzWE0J5APC2em4JlvR8EEEFMoA==",

    "https://127.0.0.1:8080/":
    "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE4qWq6afhBUi0OdcWUYhyJLNXTkGqQ9"
    "PMS5lqoCgkV2h1ZvpNjBH2u8UbgcOQwqDo66z6BWQJGolozZYmNHE2kQ==",

    "https://flimsy.ct.nordu.net/":
    "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE4qWq6afhBUi0OdcWUYhyJLNXTkGqQ9"
    "PMS5lqoCgkV2h1ZvpNjBH2u8UbgcOQwqDo66z6BWQJGolozZYmNHE2kQ==",
}

def get_cert_info(s):
    p = subprocess.Popen(
        ["openssl", "x509", "-noout", "-subject", "-issuer", "-inform", "der"],
        stdin=subprocess.PIPE, stdout=subprocess.PIPE,
        stderr=subprocess.PIPE)
    parsed = p.communicate(s)
    if parsed[1]:
        print "ERROR:", parsed[1]
        sys.exit(1)
    result = {}
    for line in parsed[0].split("\n"):
        (key, sep, value) = line.partition("=")
        if sep == "=":
            result[key] = value
    return result

def get_certs_from_file(certfile):
    certs = []
    cert = ""
    incert = False

    for line in open(certfile):
        line = line.strip()
        if line == "-----BEGIN CERTIFICATE-----":
            cert = ""
            incert = True
        elif line == "-----END CERTIFICATE-----":
            certs.append(base64.decodestring(cert))
            incert = False
        elif incert:
            cert += line
    return certs

def get_root_cert(issuer):
    accepted_certs = \
        json.loads(open("googlelog-accepted-certs.txt").read())["certificates"]

    root_cert = None

    for accepted_cert in accepted_certs:
        subject = get_cert_info(base64.decodestring(accepted_cert))["subject"]
        if subject == issuer:
            root_cert = base64.decodestring(accepted_cert)

    return root_cert

def get_sth(baseurl):
    result = urllib2.urlopen(baseurl + "ct/v1/get-sth").read()
    return json.loads(result)

def get_proof_by_hash(baseurl, hash, tree_size):
    try:
        params = urllib.urlencode({"hash":base64.b64encode(hash),
                                   "tree_size":tree_size})
        result = \
          urllib2.urlopen(baseurl + "ct/v1/get-proof-by-hash?" + params).read()
        return json.loads(result)
    except urllib2.HTTPError, e:
        print "ERROR:", e.read()
        sys.exit(1)

def tls_array(data, length_len):
    length_bytes = struct.pack(">Q", len(data))[-length_len:]
    return length_bytes + data

def unpack_tls_array(packed_data, length_len):
    padded_length = ["\x00"] * 8
    padded_length[-length_len:] = packed_data[:length_len]
    (length,) = struct.unpack(">Q", "".join(padded_length))
    unpacked_data = packed_data[length_len:length_len+length]
    assert len(unpacked_data) == length, \
      "data is only %d bytes long, but length is %d bytes" % \
      (len(unpacked_data), length)
    rest_data = packed_data[length_len+length:]
    return (unpacked_data, rest_data)

def add_chain(baseurl, submission):
    try:
        result = urllib2.urlopen(baseurl + "ct/v1/add-chain",
            json.dumps(submission)).read()
        return json.loads(result)
    except urllib2.HTTPError, e:
        print "ERROR:", e.read()
        sys.exit(1)
    except ValueError, e:
        print "==== FAILED REQUEST ===="
        print submission
        print "======= RESPONSE ======="
        print result
        print "========================"
        raise e

def get_entries(baseurl, start, end):
    try:
        params = urllib.urlencode({"start":start, "end":end})
        result = urllib2.urlopen(baseurl + "ct/v1/get-entries?" + params).read()
        return json.loads(result)
    except urllib2.HTTPError, e:
        print "ERROR:", e.read()
        sys.exit(1)

def decode_certificate_chain(packed_certchain):
    (unpacked_certchain, rest) = unpack_tls_array(packed_certchain, 3)
    assert len(rest) == 0
    certs = []
    while len(unpacked_certchain):
        (cert, rest) = unpack_tls_array(unpacked_certchain, 3)
        certs.append(cert)
        unpacked_certchain = rest
    return certs

def decode_signature(signature):
    (hash_alg, signature_alg) = struct.unpack(">bb", signature[0:2])
    (unpacked_signature, rest) = unpack_tls_array(signature[2:], 2)
    assert rest == ""
    return (hash_alg, signature_alg, unpacked_signature)

def encode_signature(hash_alg, signature_alg, unpacked_signature):
    signature = struct.pack(">bb", hash_alg, signature_alg)
    signature += tls_array(unpacked_signature, 2)
    return signature

def check_signature(baseurl, signature, data):
    publickey = base64.decodestring(publickeys[baseurl])
    (hash_alg, signature_alg, unpacked_signature) = decode_signature(signature)
    assert hash_alg == 4, \
        "hash_alg is %d, expected 4" % (hash_alg,) # sha256
    assert signature_alg == 3, \
        "signature_alg is %d, expected 3" % (signature_alg,) # ecdsa

    vk = ecdsa.VerifyingKey.from_der(publickey)
    vk.verify(unpacked_signature, data, hashfunc=hashlib.sha256,
              sigdecode=ecdsa.util.sigdecode_der)

def create_signature(privatekey, data):
    sk = ecdsa.SigningKey.from_der(privatekey)
    unpacked_signature = sk.sign(data, hashfunc=hashlib.sha256,
                                 sigencode=ecdsa.util.sigencode_der)
    return encode_signature(4, 3, unpacked_signature)

def check_sth_signature(baseurl, sth):
    signature = base64.decodestring(sth["tree_head_signature"])

    version = struct.pack(">b", 0)
    signature_type = struct.pack(">b", 1)
    timestamp = struct.pack(">Q", sth["timestamp"])
    tree_size = struct.pack(">Q", sth["tree_size"])
    hash = base64.decodestring(sth["sha256_root_hash"])
    tree_head = version + signature_type + timestamp + tree_size + hash

    check_signature(baseurl, signature, tree_head)

def create_sth_signature(tree_size, timestamp, root_hash, privatekey):
    version = struct.pack(">b", 0)
    signature_type = struct.pack(">b", 1)
    timestamp_packed = struct.pack(">Q", timestamp)
    tree_size_packed = struct.pack(">Q", tree_size)
    tree_head = version + signature_type + timestamp_packed + tree_size_packed + root_hash

    return create_signature(privatekey, tree_head)

def check_sct_signature(baseurl, leafcert, sct):
    publickey = base64.decodestring(publickeys[baseurl])
    calculated_logid = hashlib.sha256(publickey).digest()
    received_logid = base64.decodestring(sct["id"])
    assert calculated_logid == received_logid, \
        "log id is incorrect:\n  should be %s\n        got %s" % \
        (calculated_logid.encode("hex_codec"),
         received_logid.encode("hex_codec"))

    signature = base64.decodestring(sct["signature"])

    version = struct.pack(">b", sct["sct_version"])
    signature_type = struct.pack(">b", 0)
    timestamp = struct.pack(">Q", sct["timestamp"])
    entry_type = struct.pack(">H", 0)
    signed_struct = version + signature_type + timestamp + \
      entry_type + tls_array(leafcert, 3) + \
      tls_array(base64.decodestring(sct["extensions"]), 2)

    check_signature(baseurl, signature, signed_struct)

def pack_mtl(timestamp, leafcert):
    entry_type = struct.pack(">H", 0)
    extensions = ""

    timestamped_entry = struct.pack(">Q", timestamp) + entry_type + \
      tls_array(leafcert, 3) + tls_array(extensions, 2)
    version = struct.pack(">b", 0)
    leaf_type = struct.pack(">b", 0)
    merkle_tree_leaf = version + leaf_type + timestamped_entry
    return merkle_tree_leaf

def unpack_mtl(merkle_tree_leaf):
    version = merkle_tree_leaf[0:1]
    leaf_type = merkle_tree_leaf[1:2]
    timestamped_entry = merkle_tree_leaf[2:]
    (timestamp, entry_type) = struct.unpack(">QH", timestamped_entry[0:10])
    (leafcert, rest_entry) = unpack_tls_array(timestamped_entry[10:], 3)
    return (leafcert, timestamp)

def get_leaf_hash(merkle_tree_leaf):
    leaf_hash = hashlib.sha256()
    leaf_hash.update(struct.pack(">b", 0))
    leaf_hash.update(merkle_tree_leaf)

    return leaf_hash.digest()

def timing_point(timer_dict=None, name=None):
    t = datetime.datetime.now()
    if timer_dict:
        starttime = timer_dict["lasttime"]
        stoptime = t
        deltatime = stoptime - starttime
        timer_dict["deltatimes"].append((name, deltatime.seconds * 1000000 + deltatime.microseconds))
        timer_dict["lasttime"] = t
        return None
    else:
        timer_dict = {"deltatimes":[], "lasttime":t}
        return timer_dict

def internal_hash(pair):
    if len(pair) == 1:
        return pair[0]
    else:
        hash = hashlib.sha256()
        hash.update(struct.pack(">b", 1))
        hash.update(pair[0])
        hash.update(pair[1])
        return hash.digest()

def chunks(l, n):
    return [l[i:i+n] for i in range(0, len(l), n)]

def next_merkle_layer(layer):
    return [internal_hash(pair) for pair in chunks(layer, 2)]

def build_merkle_tree(layer0):
    if len(layer0) == 0:
        return [[hashlib.sha256().digest()]]
    layers = []
    current_layer = layer0
    layers.append(current_layer)
    while len(current_layer) > 1:
        current_layer = next_merkle_layer(current_layer)
        layers.append(current_layer)
    return layers