Default configuration for signing client certificate using self-signed CA

ca.conf

[ ca ]
default_ca = ca_default

[ ca_default ]
dir = ./ca
certs = $dir
new_certs_dir = $dir/ca.db.certs
database = $dir/ca.db.index
serial = $dir/ca.db.serial
RANDFILE = $dir/ca.db.rand
certificate = $dir/ca.crt
private_key = $dir/ca.key
default_days = 365
default_crl_days = 30
# SHA-1 is deprecated, so use SHA-2 instead.
default_md = sha256
preserve = no
policy = generic_policy

[ generic_policy ]
countryName = optional
stateOrProvinceName = optional
localityName = optional
organizationName = optional
organizationalUnitName = optional
commonName = optional
emailAddress = optional

[ req ]
# Options for the `req` tool (`man req`).
default_bits = 2048
string_mask = utf8only

# SHA-1 is deprecated, so use SHA-2 instead.
default_md = sha256

# Extension to add when the -x509 option is used.
x509_extensions = v3_ca