Open3

opensslでEDCSAを使った自己署名証明書を作る

takahashimtakahashim
openssl req -x509 -nodes -newkey ec:<(openssl ecparam -name secp384r1) \
  -subj "/O=takahashim/CN=localhost" \
  -keyout key.pem -out cert.pem -days 365
takahashimtakahashim

普通にRSAでよければ、

openssl req -x509 -nodes -newkey rsa:4096 \
  -subj "/O=takahashim/CN=localhost" -keyout key.pem -out cert.pem -days 365

みたいに書けばOK。