Mk/bsd.default-versions.mk advises [0]:

# Possible values: base, openssl, openssl111, openssl31, openssl32,         libressl, libressl-devel


Mk/Uses/ssl.mk advises [1]:

# Variants being base, openssl, openssl30, openssl31, openssl32,
# openssl-quictls, libressl, and libressl-devel.


Aside from "base", the following table shows all choices for "value" that are present in at least one of the two sources cited above. The columns mean:

*   port: security/$value exists
*   DVs: appears in Mk/bsd.default-versions.mk comments
*   Uses: appears in Mk/Uses/ssl.mk comments
*   IsOK: logical AND over the preceding cells

value               port    DVs     Uses    IsOK
==================  ====    ====    ====    ===
libressl            y       y       y       y
libressl-devel      y       y       y       y
openssl             y       y       y       y
openssl-quictls     y       n       y       n
openssl111          y       y       n       n
openssl30           n       n       y       n
openssl31           y       y       y       y
openssl31-quictls   y       n       n       n
openssl32           y       y       y       y


[0] https://cgit.freebsd.org/ports/tree/Mk/bsd.default-versions.mk?id=ffa8992157df1abee61aa925d8e109dc89070dcc#n147
[1] https://cgit.freebsd.org/ports/tree/Mk/Uses/ssl.mk?id=ffa8992157df1abee61aa925d8e109dc89070dcc#n11