ssh生成私钥格式可选择PKCS8/PEM/SSH2，使用ssh-keygen生成PEM格式私钥：
ssh-keygen -t rsa -P "passwd" -b 4096 -C Haiyun -m PEM -f ~/.ssh/id_rsa转换私钥格式为PKCS8或SSH2：
ssh-keygen -P "passwd" -N "passwd" -e -p -m PKCS8 -f ~/.ssh/id_rsa
ssh-keygen -P "passwd" -N "passwd" -e -p -m SSH2 -f ~/.ssh/id_rsa从ssh私钥生成openssl可识别的公钥：
ssh-keygen -e -m PKCS8 -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub.pkcs8
openssl rsa -in ~/.ssh/id_rsa -pubout -outform PEM > ~/.ssh/id_rsa.pub.pkcs8openssl使用公私钥加解密：
openssl rsautl -encrypt -pubin -inkey ~/.ssh/id_rsa.pub.pkcs8 -ssl -in test.txt -out test.enc
openssl rsautl -decrypt -inkey ~/.ssh/id_rsa -in test.enc -out test.dec