Digital Envelope

• Source: http://security.nknu.edu.tw/crypto/faq/html/2-2-4.html

Combines public and secret key encryption:

• use a secret key $‘K_1‘$ to encrypt the messsage $‘M‘$
• use the public key of the receiver to encrypt the secret key $‘K_1‘$
• the receiver will decrypt $‘K_1‘$ with its private key