# Consider an automated teller machine (ATM)

1.1 Consider an automated teller machine (ATM) in which users provide a personal identification number (PIN) and a card for account access. Give examples of confidentiality, integrity, and availability requirements associated with the system and, in each case, indicate the degree of importance of the requirement.

The telecommunication provider must maintain a secret client’s personal identification number (PIN) throughout the client’s system and transaction. Additionally, personal security identification must be encrypted. It should support the integrity of the accounting and individual transactions. The customer’s transaction registration will not be detrimental. The presence of ATMs is important, the bank increases its economic growth.

1.2 Repeat Problem 1.1 for a telephone switching system that routes calls through a switching network based on the telephone number requested by the caller

The phone system’s privacy provides individual calls while avoiding hearing the caller by the other caller. When the client uses the device, he wants privacy. Safety phone system, program control and configuration system. The phone switching system will be called when the caller uses the device when he’s available.

3.19 Using the Vigenère cipher, encrypt the word “explanation” using the key leg.

Keyword:legleglegle

Plaintext: explanation

Ciphertext:pbvwetlxozr

3.20 This problem explores the use of a one-time pad version of the Vigenère cipher. In this scheme, the key is a stream of random numbers between 0 and 26. For example, if the key is 3 19 5 . . . , then the first letter of plaintext is encrypted with a shift of 3 letters, the second with a shift of 19 letters, the third with a shift of 5 letters, and so on.

Encrypt the plaintext sendmoremoney with the key stream

9 0 1 7 23 15 21 14 11 11 2 8 9

Plaintext:sendmoremoneyPlaintext #: 18 4 13 3 12 14 17 4 12 14 13 4 24

Keyword:jabhxpvollcijkeyword #: 9 0 1 7 23 15 21 14 11 11 28 9

Ciphertext:beokjdmsxzpmhCiphertext #: 1 4 14 10 9 3 12 18 23 25 15 12 7

Using the ciphertext produced in part (a), find a key so that the cipher text decrypts to the plaintext cashnotneeded.

Plaintext: cashnotneededPlaintext #: 2 0 18 7 13 14 19 13 4 4 3 4 3

Keyword:zewdwptneededKeyword #: 25 4 22 3 22 15 19 5 19 21 12 8 4

Ciphertext: beokjdmsxzpmhCiphertext #: 1 4 14 10 9 3 12 18 23 25 15 12 7