Question

Suppose Bob has a whitelist, denoted as L, of a group of people with whom he has the agreement that, Bob will transfer a piece of data asset in the form of a private key every time anyone on this whitelist provides Bob a secured file into which Bob will write the private key to the data asset. Design a scheme with asymmetric encryption, such that the transfer would satisfy the following conditions: 1) Anyone on the whitelist L can let Bob know the password to a secured file in which Bob can put in the key to the data asset. The password and the location of the secured file are packaged into a message denoted by m. 2) When Bob receives a message, he must be able to make sure that the message m is sent by one of the people on L, not anyone else. 3) The sender must be able to make sure that the original message m can only been seen by Bob, not anyone else

Answer 1

To satisfy the given conditions, a scheme using asymmetric encryption and digital signatures can be used. Bob generates a key pair and shares the public key with the whitelist. Sender encrypts the message using Bob's public key and digitally signs it. Bob decrypts the message using his private key and verifies the signature.

Step-by-step explanation:

To design a scheme using asymmetric encryption that satisfies the given conditions, we can use a combination of public key cryptography and digital signatures:

Bob will generate a key pair consisting of a public key and a private key. The public key will be shared with everyone on the whitelist L.

When someone on the whitelist wants to send a message to Bob, they will encrypt the message using Bob's public key and send it to Bob.

Bob can decrypt the message using his private key, ensuring that only he can read the original message.

To ensure that the message is sent by someone on the whitelist, the sender can digitally sign the message using their private key. Bob can verify the digital signature using the sender's public key. If the signature is valid, it means the message was sent by someone on the whitelist.