ASN.1 UTCTime uses two-digit years. While X.680 does not specify how to
map them as far as I can tell, X.509/PKIX uses this type to represent
dates between year 1950-2049.
OpenSSL::ASN1.decode has used 1969-2068 since the initial
implementation. Given that ASN1::UTCTime#to_der relies on OpenSSL
ASN1_UTCTIME type, which assumes the 1950-2049 range, this was likely
unintentional.
Use the range 1950-2049 consistently, and fix decoding of X.509
certificates with dates in 1950-1968.
https://github.com/ruby/openssl/commit/b8b38e1438
753e3b7ae3