RSA re-encryption scheme
As PulpSpy have mentioned, It is called proxy re-encryption. A company called NyCypher have implemented it but with secp251 keys https://blog.nucypher.com/proxy-re-encryption-playground-in-python-3bc66170b9bf. 
Other option is charm-crypto,https://github.com/JHUISI/charm/tree/2.7-master