'Create an L{SerialNumber} instance from a date string in format
\'YYYYMMDDHHMMSS\' described in U{RFC4034
3.2<https://tools.ietf.org/html/rfc4034#section-3.2>}.
The L{SerialNumber} instance stores the date as a 32bit UNIX timestamp.
@see: U{https://tools.ietf.org/html/rfc4034#section-3.1.5}
@param utcDateString: A UTC date/time string of format I{YYMMDDhhmmss}
which will be converted to seconds since the UNIX epoch.
@type utcDateString: L{unicode}
@return: An L{SerialNumber} instance containing the supplied date as a
32bit UNIX timestamp.'

@classmethod
def fromRFC4034DateString(cls, utcDateString):

    parsedDate = datetime.strptime(utcDateString, RFC4034_TIME_FORMAT)
    secondsSinceEpoch = calendar.timegm(parsedDate.utctimetuple())
    return cls(secondsSinceEpoch, serialBits=32)
