如何在php中将原始rsa密钥转换为RFC 7468格式

I have public key and private key in raw string format like

MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA1WWRykdXuvMOnRyYCesJpozgaRSoA....

I want to convert this to below format

-----BEGIN PRIVATE KEY-----
........................
........................
........................
-----END PRIVATE KEY-----

In the php openssl_get_privatekey not able to read public and private key from raw string

If is there any other way to read private and public key from the raw string in php, Please let me how i can do this.