(1)生成原始RSA私钥文件 rsa_private_key.pem(原始私钥)
openssl genrsa -out rsa_private_key.pem 2048
(2)将原始RSA私钥转换为pkcs8格式private_key.pem（私钥）
openssl pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt -out private_key.pem
(3)生成RSA公钥 rsa_public_key.pem(公钥)
openssl rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem