This file is indexed.

/usr/lib/python3/dist-packages/ecdsa/keys.py is in python3-ecdsa 0.11-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  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
276
277
278
279
280
281
282
import binascii

from . import ecdsa
from . import der
from . import rfc6979
from .curves import NIST192p, find_curve
from .util import string_to_number, number_to_string, randrange
from .util import sigencode_string, sigdecode_string
from .util import oid_ecPublicKey, encoded_oid_ecPublicKey
from six import PY3, b
from hashlib import sha1

class BadSignatureError(Exception):
    pass
class BadDigestError(Exception):
    pass

class VerifyingKey:
    def __init__(self, _error__please_use_generate=None):
        if not _error__please_use_generate:
            raise TypeError("Please use SigningKey.generate() to construct me")

    @classmethod
    def from_public_point(klass, point, curve=NIST192p, hashfunc=sha1):
        self = klass(_error__please_use_generate=True)
        self.curve = curve
        self.default_hashfunc = hashfunc
        self.pubkey = ecdsa.Public_key(curve.generator, point)
        self.pubkey.order = curve.order
        return self

    @classmethod
    def from_string(klass, string, curve=NIST192p, hashfunc=sha1,
                    validate_point=True):
        order = curve.order
        assert len(string) == curve.verifying_key_length, \
               (len(string), curve.verifying_key_length)
        xs = string[:curve.baselen]
        ys = string[curve.baselen:]
        assert len(xs) == curve.baselen, (len(xs), curve.baselen)
        assert len(ys) == curve.baselen, (len(ys), curve.baselen)
        x = string_to_number(xs)
        y = string_to_number(ys)
        if validate_point:
            assert ecdsa.point_is_valid(curve.generator, x, y)
        from . import ellipticcurve
        point = ellipticcurve.Point(curve.curve, x, y, order)
        return klass.from_public_point(point, curve, hashfunc)

    @classmethod
    def from_pem(klass, string):
        return klass.from_der(der.unpem(string))

    @classmethod
    def from_der(klass, string):
        # [[oid_ecPublicKey,oid_curve], point_str_bitstring]
        s1,empty = der.remove_sequence(string)
        if empty != b(""):
            raise der.UnexpectedDER("trailing junk after DER pubkey: %s" %
                                    binascii.hexlify(empty))
        s2,point_str_bitstring = der.remove_sequence(s1)
        # s2 = oid_ecPublicKey,oid_curve
        oid_pk, rest = der.remove_object(s2)
        oid_curve, empty = der.remove_object(rest)
        if empty != b(""):
            raise der.UnexpectedDER("trailing junk after DER pubkey objects: %s" %
                                    binascii.hexlify(empty))
        assert oid_pk == oid_ecPublicKey, (oid_pk, oid_ecPublicKey)
        curve = find_curve(oid_curve)
        point_str, empty = der.remove_bitstring(point_str_bitstring)
        if empty != b(""):
            raise der.UnexpectedDER("trailing junk after pubkey pointstring: %s" %
                                    binascii.hexlify(empty))
        assert point_str.startswith(b("\x00\x04"))
        return klass.from_string(point_str[2:], curve)

    def to_string(self):
        # VerifyingKey.from_string(vk.to_string()) == vk as long as the
        # curves are the same: the curve itself is not included in the
        # serialized form
        order = self.pubkey.order
        x_str = number_to_string(self.pubkey.point.x(), order)
        y_str = number_to_string(self.pubkey.point.y(), order)
        return x_str + y_str

    def to_pem(self):
        return der.topem(self.to_der(), "PUBLIC KEY")

    def to_der(self):
        order = self.pubkey.order
        x_str = number_to_string(self.pubkey.point.x(), order)
        y_str = number_to_string(self.pubkey.point.y(), order)
        point_str = b("\x00\x04") + x_str + y_str
        return der.encode_sequence(der.encode_sequence(encoded_oid_ecPublicKey,
                                                       self.curve.encoded_oid),
                                   der.encode_bitstring(point_str))

    def verify(self, signature, data, hashfunc=None, sigdecode=sigdecode_string):
        hashfunc = hashfunc or self.default_hashfunc
        digest = hashfunc(data).digest()
        return self.verify_digest(signature, digest, sigdecode)

    def verify_digest(self, signature, digest, sigdecode=sigdecode_string):
        if len(digest) > self.curve.baselen:
            raise BadDigestError("this curve (%s) is too short "
                                 "for your digest (%d)" % (self.curve.name,
                                                           8*len(digest)))
        number = string_to_number(digest)
        r, s = sigdecode(signature, self.pubkey.order)
        sig = ecdsa.Signature(r, s)
        if self.pubkey.verifies(number, sig):
            return True
        raise BadSignatureError

class SigningKey:
    def __init__(self, _error__please_use_generate=None):
        if not _error__please_use_generate:
            raise TypeError("Please use SigningKey.generate() to construct me")

    @classmethod
    def generate(klass, curve=NIST192p, entropy=None, hashfunc=sha1):
        secexp = randrange(curve.order, entropy)
        return klass.from_secret_exponent(secexp, curve, hashfunc)

    # to create a signing key from a short (arbitrary-length) seed, convert
    # that seed into an integer with something like
    # secexp=util.randrange_from_seed__X(seed, curve.order), and then pass
    # that integer into SigningKey.from_secret_exponent(secexp, curve)

    @classmethod
    def from_secret_exponent(klass, secexp, curve=NIST192p, hashfunc=sha1):
        self = klass(_error__please_use_generate=True)
        self.curve = curve
        self.default_hashfunc = hashfunc
        self.baselen = curve.baselen
        n = curve.order
        assert 1 <= secexp < n
        pubkey_point = curve.generator*secexp
        pubkey = ecdsa.Public_key(curve.generator, pubkey_point)
        pubkey.order = n
        self.verifying_key = VerifyingKey.from_public_point(pubkey_point, curve,
                                                            hashfunc)
        self.privkey = ecdsa.Private_key(pubkey, secexp)
        self.privkey.order = n
        return self

    @classmethod
    def from_string(klass, string, curve=NIST192p, hashfunc=sha1):
        assert len(string) == curve.baselen, (len(string), curve.baselen)
        secexp = string_to_number(string)
        return klass.from_secret_exponent(secexp, curve, hashfunc)

    @classmethod
    def from_pem(klass, string, hashfunc=sha1):
        # the privkey pem file has two sections: "EC PARAMETERS" and "EC
        # PRIVATE KEY". The first is redundant.
        if PY3 and isinstance(string, str):
            string = string.encode()
        privkey_pem = string[string.index(b("-----BEGIN EC PRIVATE KEY-----")):]
        return klass.from_der(der.unpem(privkey_pem), hashfunc)
    @classmethod
    def from_der(klass, string, hashfunc=sha1):
        # SEQ([int(1), octetstring(privkey),cont[0], oid(secp224r1),
        #      cont[1],bitstring])
        s, empty = der.remove_sequence(string)
        if empty != b(""):
            raise der.UnexpectedDER("trailing junk after DER privkey: %s" %
                                    binascii.hexlify(empty))
        one, s = der.remove_integer(s)
        if one != 1:
            raise der.UnexpectedDER("expected '1' at start of DER privkey,"
                                    " got %d" % one)
        privkey_str, s = der.remove_octet_string(s)
        tag, curve_oid_str, s = der.remove_constructed(s)
        if tag != 0:
            raise der.UnexpectedDER("expected tag 0 in DER privkey,"
                                    " got %d" % tag)
        curve_oid, empty = der.remove_object(curve_oid_str)
        if empty != b(""):
            raise der.UnexpectedDER("trailing junk after DER privkey "
                                    "curve_oid: %s" % binascii.hexlify(empty))
        curve = find_curve(curve_oid)

        # we don't actually care about the following fields
        #
        #tag, pubkey_bitstring, s = der.remove_constructed(s)
        #if tag != 1:
        #    raise der.UnexpectedDER("expected tag 1 in DER privkey, got %d"
        #                            % tag)
        #pubkey_str = der.remove_bitstring(pubkey_bitstring)
        #if empty != "":
        #    raise der.UnexpectedDER("trailing junk after DER privkey "
        #                            "pubkeystr: %s" % binascii.hexlify(empty))

        # our from_string method likes fixed-length privkey strings
        if len(privkey_str) < curve.baselen:
            privkey_str = b("\x00")*(curve.baselen-len(privkey_str)) + privkey_str
        return klass.from_string(privkey_str, curve, hashfunc)

    def to_string(self):
        secexp = self.privkey.secret_multiplier
        s = number_to_string(secexp, self.privkey.order)
        return s

    def to_pem(self):
        # TODO: "BEGIN ECPARAMETERS"
        return der.topem(self.to_der(), "EC PRIVATE KEY")

    def to_der(self):
        # SEQ([int(1), octetstring(privkey),cont[0], oid(secp224r1),
        #      cont[1],bitstring])
        encoded_vk = b("\x00\x04") + self.get_verifying_key().to_string()
        return der.encode_sequence(der.encode_integer(1),
                                   der.encode_octet_string(self.to_string()),
                                   der.encode_constructed(0, self.curve.encoded_oid),
                                   der.encode_constructed(1, der.encode_bitstring(encoded_vk)),
                                   )

    def get_verifying_key(self):
        return self.verifying_key

    def sign_deterministic(self, data, hashfunc=None, sigencode=sigencode_string):
        hashfunc = hashfunc or self.default_hashfunc
        digest = hashfunc(data).digest()

        return self.sign_digest_deterministic(digest, hashfunc=hashfunc, sigencode=sigencode)

    def sign_digest_deterministic(self, digest, hashfunc=None, sigencode=sigencode_string):
        """
        Calculates 'k' from data itself, removing the need for strong
        random generator and producing deterministic (reproducible) signatures.
        See RFC 6979 for more details.
        """
        secexp = self.privkey.secret_multiplier
        k = rfc6979.generate_k(self.curve.generator, secexp, hashfunc, digest)

        return self.sign_digest(digest, sigencode=sigencode, k=k)

    def sign(self, data, entropy=None, hashfunc=None, sigencode=sigencode_string, k=None):
        """
        hashfunc= should behave like hashlib.sha1 . The output length of the
        hash (in bytes) must not be longer than the length of the curve order
        (rounded up to the nearest byte), so using SHA256 with nist256p is
        ok, but SHA256 with nist192p is not. (In the 2**-96ish unlikely event
        of a hash output larger than the curve order, the hash will
        effectively be wrapped mod n).

        Use hashfunc=hashlib.sha1 to match openssl's -ecdsa-with-SHA1 mode,
        or hashfunc=hashlib.sha256 for openssl-1.0.0's -ecdsa-with-SHA256.
        """

        hashfunc = hashfunc or self.default_hashfunc
        h = hashfunc(data).digest()
        return self.sign_digest(h, entropy, sigencode, k)

    def sign_digest(self, digest, entropy=None, sigencode=sigencode_string, k=None):
        if len(digest) > self.curve.baselen:
            raise BadDigestError("this curve (%s) is too short "
                                 "for your digest (%d)" % (self.curve.name,
                                                           8*len(digest)))
        number = string_to_number(digest)
        r, s = self.sign_number(number, entropy, k)
        return sigencode(r, s, self.privkey.order)

    def sign_number(self, number, entropy=None, k=None):
        # returns a pair of numbers
        order = self.privkey.order
        # privkey.sign() may raise RuntimeError in the amazingly unlikely
        # (2**-192) event that r=0 or s=0, because that would leak the key.
        # We could re-try with a different 'k', but we couldn't test that
        # code, so I choose to allow the signature to fail instead.

        # If k is set, it is used directly. In other cases
        # it is generated using entropy function
        if k is not None:
            _k = k
        else:
            _k = randrange(order, entropy)

        assert 1 <= _k < order
        sig = self.privkey.sign(number, _k)
        return sig.r, sig.s