Explain the threat in each of the following types of authentication and provide a solution for each scenario below: Alice sends a password, and Bob compares it against a database of passwords. Alice (the sender) converts her message into a hash value and encrypts the hash value using her private key. This encrypted hash value is the digital signature.

Can a hash value be protected such that it may be used for message authentication? Is it possible to attack a MAC technique without discovering the key's ciphertext?

To solve the following issue, you must first identify the vulnerabilities in each authentication technique.Passwords are validated by Bob by first hashing them and then looking them up in a database of hashes.Bob uses a hashing method to verify a password against a list of previously hashed passwords.

Find out what risks are involved with the various authentication techniques and suggest a way to deal with the following situation.Bob uses a cryptographic hash function to check a password against a cache of other hashes.Bob performs a cryptographic hash on a password and checks it against a database of previously double-hashed passwords.

Alice and Bod have decided to use a symmetric encryption algorithm. They have some assumptions about their messages:- Messages only contain capital letters (i.e. A to Z)- The length of their shared key must be greater than or equal to the length of the plaintext- They assign each letter a number as follows: (A,0), (B,1), (C,2), (D,3),…, (Z,25)Their algorithm combines the key and the message using modular addition. The numerical values of corresponding message and key letters are added together, modulo 26. For example, if the plain text is “HELLO” and the key is “SECRET” then the encrypted message is calculated as following:Since the length of the plaintext is 5, we just need the first 5 letters of the key (i.e. “SECRE”), then for each letter, we should add corresponding letters in both the plaintext and the key modulo 26.Plaintext: H (7) E (4) L (11) L (11) O (14)Key: S (18) E (4) C (2) R (17) E(4)Cipher: Z (25) I (8) N(13) C(2) S (18) Write a program in Python, C/C++ or JavaScript to…