Update doc/ca.pod to clarify description for dates

"Note" part is based on PR #3566

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3895)

1 files changed, 14 insertions, 2 deletions

diff --git a/doc/man1/ca.pod b/doc/man1/ca.pod
index 4a5970892c..ab8ce7211f 100644
--- a/doc/man1/ca.pod
+++ b/doc/man1/ca.pod
@@ -164,12 +164,16 @@ Don't output the text form of a certificate to the output file.
 =item B<-startdate date>
 
 This allows the start date to be explicitly set. The format of the
-date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure).
+date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure), or
+YYYYMMDDHHMMSSZ (the same as an ASN1 GeneralizedTime structure). In
+both formats, seconds SS and timzone Z must be present.
 
 =item B<-enddate date>
 
 This allows the expiry date to be explicitly set. The format of the
-date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure).
+date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure), or
+YYYYMMDDHHMMSSZ (the same as an ASN1 GeneralizedTime structure). In
+both formats, seconds SS and timzone Z must be present.
 
 =item B<-days arg>
 
@@ -716,6 +720,14 @@ For example if the CA certificate has:
 
 then even if a certificate is issued with CA:TRUE it will not be valid.
 
+=head1 HISTORY
+
+Since OpenSSL 1.1.1, the program follows RFC5280. Specifically,
+certificate validity period (specified by any of B<-startdate>,
+B<-enddate> and B<-days>) will be encoded as UTCTime if the dates are
+earlier than year 2049 (included), and as GeneralizedTime if the dates
+are in year 2050 or later.
+
 =head1 SEE ALSO
 
 L<req(1)>, L<spkac(1)>, L<x509(1)>, L<CA.pl(1)>,