crypt_bug.py

# -*- coding: utf-8 -*-
from cryptography import x509
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives import serialization

from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.x509.oid import NameOID
import datetime
import uuid

def create_ca():
    one_day = datetime.timedelta(1, 0, 0)
    private_key = rsa.generate_private_key(
        public_exponent=65537,
        key_size=4096,
        backend=default_backend()
    )
    builder = x509.CertificateBuilder()
    builder = builder.subject_name(x509.Name([
        x509.NameAttribute(NameOID.COMMON_NAME, u'localhost'),
        x509.NameAttribute(NameOID.ORGANIZATION_NAME, u'Göteborg Bit Factory'),
    ]))
    builder = builder.issuer_name(x509.Name([
        x509.NameAttribute(NameOID.COMMON_NAME, u'localhost'),
        x509.NameAttribute(NameOID.ORGANIZATION_NAME, u'Göteborg Bit Factory'),
    ]))
    builder = builder.not_valid_before(datetime.datetime.today() - one_day)
    builder = builder.not_valid_after(datetime.datetime(2017, 8, 2))
    builder = builder.serial_number(int(uuid.uuid4()))
    builder = builder.public_key(private_key.public_key())
    certificate = builder.sign(
        private_key=private_key, algorithm=hashes.SHA256(),
        backend=default_backend()
    )
    return private_key, certificate


def sign_cert(our_ca_key, ca_cert):
    one_day = datetime.timedelta(1, 0, 0)
    private_key = rsa.generate_private_key(
        public_exponent=65537,
        key_size=4096,
        backend=default_backend()
    )
    public_key = private_key.public_key()

    
    builder = x509.CertificateBuilder()
    builder = builder.subject_name(x509.Name([
        x509.NameAttribute(NameOID.COMMON_NAME, u'localhost'),
        x509.NameAttribute(NameOID.ORGANIZATION_NAME, u'Göteborg Bit Factory'),
    ]))
    # QUE?????
    builder = builder.issuer_name(ca_cert.subject)
    builder = builder.not_valid_before(datetime.datetime.today() - one_day)
    builder = builder.not_valid_after(datetime.datetime(2017, 8, 2))
    builder = builder.serial_number(int(uuid.uuid4()))
    builder = builder.public_key(public_key)
    builder = builder.add_extension(
        x509.BasicConstraints(ca=False, path_length=None), critical=True,
    )
    builder = builder.add_extension(
        x509.KeyUsage(digital_signature=True, content_commitment=False, key_encipherment=True,
                      data_encipherment=False, key_agreement=False, key_cert_sign=False,
                      crl_sign=False, encipher_only=False, decipher_only=False), critical=True
        )
    builder = builder.add_extension(
        x509.ExtendedKeyUsage([x509.oid.ExtendedKeyUsageOID.CLIENT_AUTH]), critical=False
        )
    builder = builder.add_extension(
        x509.SubjectKeyIdentifier.from_public_key(public_key), critical=False
        )
    builder = builder.add_extension(
        x509.AuthorityKeyIdentifier.from_issuer_public_key(ca_cert.public_key()), critical=False
        )

    certificate = builder.sign(
        private_key=our_ca_key, algorithm=hashes.SHA256(),
        backend=default_backend()
    )
    private_key_pem = private_key.private_bytes(
        encoding=serialization.Encoding.PEM,
        format=serialization.PrivateFormat.TraditionalOpenSSL,
        encryption_algorithm=serialization.NoEncryption()
    )
    cert_pem = certificate.public_bytes(serialization.Encoding.PEM)
    
    return (cert_pem, private_key_pem)

if __name__ == '__main__':
    with open("test.cert.pem", 'wb') as f_cert, open("test.key.pem", 'wb') as f_key, open("test.ca.cert.pem", 'wb') as f_cacert, open("tes.ca.key.pem", 'wb') as f_cakey:
        our_ca_key, ca_cert = create_ca()
        f_cakey.write(our_ca_key.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.TraditionalOpenSSL,
            encryption_algorithm=serialization.NoEncryption()
        ))
        f_cacert.write(ca_cert.public_bytes(serialization.Encoding.PEM))
        cert, key = sign_cert(our_ca_key, ca_cert)
        f_cert.write(cert)
        f_key.write(key)