Cannot create secrets via an openshift template as Base64 decoded value

Issue

When we create secret object via a template, we should have to input the parameter as Base64 encoded string. Here is the description of data field of secret object.

$ oc explain secret.data
FIELD: data <object>

DESCRIPTION:
     Data contains the secret data. Each key must be a valid DNS_SUBDOMAIN or
     leading dot followed by valid DNS_SUBDOMAIN. The serialized form of the
     secret data is a base64 encoded string, representing the arbitrary (possibly
     non-string) data value here. Described in
     https://tools.ietf.org/html/rfc4648#section-4

However, input Base64 encoded string is not useful and we can't use generate option for secret value because there is no mechanism for generate Base64 encoded string in OpenShift template.