Key distribution with RSA

Alice encrypts $M$ by using Bob’s public key $(e,n)$.

• Alice randomly chooses a secret key $K$ to be shared with Bob.
• Alice sends $C=(K^e\text{ mod }n,E_K(M))$ to Bob.

Bob decrypts $C$ with his private key $(d,n)$.

• Bob splits $C$ into $(C_1,C_2)$.
• Bob computes $K=C_1^d\text{ mod }n$ and $M=D_K(C_2)$.