Which of the following key lengths is not available in an AES cryptosystem? a. 128 bits b. 192 bits c. 256 bits d. 512 bits Matthew would like to send a private message to Richard using an asymmetric...

Which of the following key lengths is not available in an AES cryptosystem? a. 128 bits b. 192 bits c. 256 bits d. 512 bits Matthew would like to send a private message to Richard using an asymmetric cryptosystem. What key should Matthew use to encrypt the message? a. Matthew’s public key b. Matthew’s private key c. Richard’s public key d. Richard’s private key e. Shared secret key