Not conforming to RFC5280 - certificate use GENERALIZEDTIME for dates <2050

Generated certificate use GENERALIZEDTIME for dates <2050.

According to this RFC https://tools.ietf.org/html/rfc5280#section-4.1.2.5:

CAs conforming to this profile MUST always encode certificate
validity dates through the year 2049 as UTCTime; certificate validity
dates in 2050 or later MUST be encoded as GeneralizedTime.

Here is a test ca.crt generated with django-x509:

Here is a matching test cert.crt:

Verification using LibreSSL fails:

$ openssl verify -CAfile ca.crt cert.crt
cert.crt: emailAddress = xxxx@xxxxxxx.com, CN = server-ca
error 13 at 1 depth lookup:format error in certificate's notBefore field
emailAddress = xxxx@xxxxxxx.com, CN = server-ca
error 13 at 1 depth lookup:format error in certificate's notBefore field
emailAddress = xxxx@xxxxxxx.com, CN = server-ca
error 13 at 1 depth lookup:format error in certificate's notBefore field

That is because LibreSSL has intentionaly stricter parser and
CA uses GENERALIZEDTIME:

$ openssl asn1parse -in ca.crt | grep TIME
  106:d=3  hl=2 l=  15 prim: GENERALIZEDTIME   :20181212000000Z
  123:d=3  hl=2 l=  15 prim: GENERALIZEDTIME   :20191213000000Z

Weird! I didn't notice that at all.
Thanks for reporting.
I guess changing these parts is necessary:

django-x509/django_x509/base/models.py

Lines 266 to 267 in d59efde

    
           cert.set_notBefore(bytes_compat(self.validity_start.strftime(generalized_time))) 
        
           cert.set_notAfter(bytes_compat(self.validity_end.strftime(generalized_time)))

django-x509/django_x509/base/models.py

Lines 328 to 333 in d59efde

    
           self.validity_start = datetime.strptime(not_before, 
        
                                                   generalized_time) 
        
           self.validity_start = timezone.make_aware(self.validity_start) 
        
           not_after = cert.get_notAfter().decode('utf8') 
        
           self.validity_end = datetime.strptime(not_after, 
        
                                                 generalized_time)

Although generalized_time is also used in the CRL, not sure if that's an issue as well:

django-x509/django_x509/base/models.py

Line 456 in d59efde

now_str = timezone.now().strftime(generalized_time)

@ezaquarii can you test the PR #77 when you have time?
I tested it and it looks good to me.

	cert.set_notBefore(bytes_compat(self.validity_start.strftime(generalized_time)))
	cert.set_notAfter(bytes_compat(self.validity_end.strftime(generalized_time)))

	self.validity_start = datetime.strptime(not_before,
	generalized_time)
	self.validity_start = timezone.make_aware(self.validity_start)
	not_after = cert.get_notAfter().decode('utf8')
	self.validity_end = datetime.strptime(not_after,
	generalized_time)