[Pkg-openssl-devel] Bug#862335: openssl creates and accepts certificates with bad notAfter field

[Tim Rühsen]

On Thu, 11 May 2017 18:42:17 +0200 Kurt Roeckx <kurt at roeckx.be> wrote:
> On Thu, May 11, 2017 at 02:59:20PM +0200, Harald Dunkel wrote:
>> 
>> Please note the "-enddate 20451231235959Z" and compare with RFC
>> 5280 section 4.1.2.5 (https://www.ietf.org/rfc/rfc5280.txt). The
>> GeneralizedTime format is not allowed for 2045, but apparently
>> openssl doesn't convert the string to UTCTime format.
> 
> Please note that the manual says the format is: YYMMDDHHMMSSZ
> 
> I guess it would be nice we converted it properly.

Just for the record, the latest openssl (1.1.1-dev from Github) accepts
this (seen from the code):

[SS] is optional, <+|-> = either + or - must be present

1.
YYMMDDHHMM[SS]Z YYMMDDHHMM[SS]<+|->hhmm
If valid, these date strings are written to ASN.1 into an UTCTime field.

2.
YYYYMMDDHHMM[SS]Z or YYYYMMDDHHMMSS<+|->hhmm
If valid, these date strings are written to ASN.1 into a GeneralizedTime
field.

Regarding RFC5280 in both cases (UTCTime and GeneralizedTime) the
seconds (SS) and Z (Zulu) timezone is a MUST.

See RFC5280 '4.1.2.5.1.  UTCTime' and '4.1.2.5.2.  GeneralizedTime'.

OpenSSL relies on their ASN.1 code to check for validity, which is
simply not strict enough. Other implementors do a strict check and thus
might reject certificates generated by openssl.

Regards, Tim

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