openssl_public_encrypt() - Encrypts data with public key
openssl_public_decrypt() - Decrypts data with public key
openssl_private_encrypt() - Encrypts data with private key
openssl_private_decrypt() - Decrypts data with private key
OPENSSL
openssl genrsa -des3 -out privkey.pem 2048
openssl rsa -in privkey.pem -out privkey.pem
openssl rsa -in privkey.pem -pubout -out public.key
具体实现代码详见：
https://github.com/uniqid/codebase/blob/master/common/lib/rsa.php