Bob has to send digitally signed messages (documents) to his banks. The digital signature scheme used by the banks is based on RSA. It is the simple scheme, discussed initially in the lectures, which does not use padding. However, this digital signature scheme uses hashing to generate fixed length signatures.

The hash function used in the digital signature scheme is h(x)=xmod31h(x)=xmod31. (The value returned by the hash function is the remainder after division of the argument xx by 31.) It is not a good hash function. It is being used here to keep calculations simple. Bob registers his public key with a Certification Authority (CA). The Certification Authority makes Bob's certified public key available to anyone who needs to authenticate messages received from Bob. Bob randomly chooses two 'large' prime numbers, 5 and 13, and then registers with the Certification Authority the pair of integers <65, 5> as his public key. Bob now has a message (document) to send to one of his banks. The content of the message is the integer 53. What is the hash value (message digest) of the document? Enter the hash value in the box provided below: The hash value: Answer. The signed message Bob sends to the bank is a pair of integers , where the second integer, s, is the digital signature.

What is the signed message that Bob sends?