# -*- coding: utf-8 -*-
#
# ===================================================================
# The contents of this file are dedicated to the public domain. To
# the extent that dedication to the public domain is not available,
# everyone is granted a worldwide, perpetual, royalty-free,
# non-exclusive license to exercise all rights associated with the
# contents of this file for any purpose whatsoever.
# No rights are reserved.
#
# 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 Cryptodome.Util.asn1 import (DerSequence, DerInteger, DerBitString,
DerObjectId, DerNull)
def _expand_subject_public_key_info(encoded):
"""Parse a SubjectPublicKeyInfo structure.
It returns a triple with:
* OID (string)
* encoded public key (bytes)
* Algorithm parameters (bytes or None)
"""
#
# SubjectPublicKeyInfo ::= SEQUENCE {
# algorithm AlgorithmIdentifier,
# subjectPublicKey BIT STRING
# }
#
# AlgorithmIdentifier ::= SEQUENCE {
# algorithm OBJECT IDENTIFIER,
# parameters ANY DEFINED BY algorithm OPTIONAL
# }
#
spki = DerSequence().decode(encoded, nr_elements=2)
algo = DerSequence().decode(spki[0], nr_elements=(1,2))
algo_oid = DerObjectId().decode(algo[0])
spk = DerBitString().decode(spki[1]).value
if len(algo) == 1:
algo_params = None
else:
try:
DerNull().decode(algo[1])
algo_params = None
except:
algo_params = algo[1]
return algo_oid.value, spk, algo_params
def _create_subject_public_key_info(algo_oid, secret_key, params=None):
if params is None:
params = DerNull()
spki = DerSequence([
DerSequence([
DerObjectId(algo_oid),
params]),
DerBitString(secret_key)
])
return spki.encode()
def _extract_subject_public_key_info(x509_certificate):
"""Extract subjectPublicKeyInfo from a DER X.509 certificate."""
certificate = DerSequence().decode(x509_certificate, nr_elements=3)
tbs_certificate = DerSequence().decode(certificate[0],
nr_elements=range(6, 11))
index = 5
try:
tbs_certificate[0] + 1
# Version not present
version = 1
except TypeError:
version = DerInteger(explicit=0).decode(tbs_certificate[0]).value
if version not in (2, 3):
raise ValueError("Incorrect X.509 certificate version")
index = 6
return tbs_certificate[index]