security keypair

   create-keypair [-h] [-a alg] [-s size] [-f date] [-t date]
      [-d days] [-k keychain] [-A|-T appPath] [name]

            Create an asymmetric key pair.

            -a alg          Use alg as the algorithm, can be rsa, dh, dsa or fee (default rsa)
            -s size         Specify the keysize in bits (default 512)
            -f date         Make a key valid from the specified date
            -t date         Make a key valid to the specified date
            -d days         Make a key valid for the number of days specified from today
            -k keychain     Use the specified keychain rather than the default
            -A              Allow any application to access this key without warning (insecure, not recommended!)
                            mended!)
            -T appPath      Specify an application which may access this key (multiple -T options are
                            allowed)

“Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure, or nothing” ~ Helen Keller

Related macOS commands:

security - Administer Keychains, keys, certificates and the Security framework.