2. (Cryptographic Tools, 25 points] Cryptography is one of the fundamental security techniques to protect communications and data used by applications. Consider you are going to develop an online banking system that will allow customers to check their account balance and transfer fund. a. In the threat modeling phase, your team member identified a repudiation threat against the transfer fund operation. Give a simple example of what it is, and present a cryptographic mitigation technique. [9 points) b. Encryption will be used to protect some private information. Instead of using DES algorithm. considering performance, your team member proposed to use a much faster encryption algorithm based on XOR as follows: void EncryptData(char *szkey, DWORD dwKeyLen, char *szData, DWORD dwDatalen) { for (int i = 0; i Discuss why this is a bad iden. (8 points) c. Another team member proposed to use double DES instead of single DES due to the short key size of the latter. Discuss why this is a bad idea. [8 points)