ssl certification

[Lu, Chenyang]

Hi~

    Forgive me for not being familiar with SSL.

    When I try to use SSL certification function.(in postgresql9.5.22)
The service uses the following configuration
Set ssl=on in postgresql.conf
　　　Set ssl_cert_file=server.crt in postgresql.conf
　　　Set ssl_key_file=server.key in postgresql.conf
　　　Set ssl_ca_file=root.crt in postgresql.conf
CASE 1. Add hostssl    test             all             all             md5 in 
pg_hba.conf
CASE 2. Add hostssl    test             all             all             cert in 
pg_hba.conf

    In CASE 1 : use  psql -U test -d 
"postgresql://193.xxx.xxx.xxx/test?sslmode=verify-ca"
                I can connect normally.
    In CASE 2 : use  the same connection string
                I got "psql: FATAL:  connection requires a valid client 
certificate (10689)"

    Question:cert in pg_hba.conf means what? How can I configure the client 
Certificate it needs.

    Thanks~