information security 2

Write the questions followed by your answers.

1.      Using a ROT5 cipher encrypt the following plaintext. Prove your answer by showing the steps for both the encryption and decryption. (20 points)

Meet at the baseball field at three oclock

[ your answer goes here ]

Using a ROT3 cipher decrypt the following ciphertext.

      WKHF  RUYH  WWHL  VUHG

[ your answer goes here ]

2.      Following are two problems using a rail fence cipher. Prove both of your answers by showing the steps involved in encryption/decryption.  As [art of this problem you must also show the steps involved in reversing what you are being asked for.  (20 points)

Using a rail fence cipher with a depth of 2 encrypt the following message:

The bird is a raven

[ your answer goes here ]

Reverse the steps to decrypt your answer and explain the steps.

[ your answer goes here ]

Using a rail fence cipher with zig zag pattern and a depth of 3 decrypt the following message:

      MAEKN   ETTHPRAOEM  ETATP

[ your answer goes here ]

Reverse the steps to encrypt your answer and explain the steps.

[ your answer goes here ]

3.      This is a three part question. For each part the answer requires identifying an asymmetric encryption technique, hashing or both. As part of each question you need to discuss the technique to demonstrate your understanding of how the functionality (confidentiality, authenticity, integrity) is supported. You need to discuss the details of what the sender and receiver do and the key usage if applicable. (25 points)

1. What technique is used to exchange messages between two parties ensuring confidentiality? Discuss.

[ your answer goes here. ]

1. What technique is used to exchange messages between two parties ensuring authenticity? Discuss.

[ your answer goes here. ]

c. What technique is used to exchange messages between two parties ensuring integrity? Discuss.

[ your answer goes here. ]

4.      Logical operations. Neatly align your result under the operands. (25 points)

Perform a logical AND on the following two binary strings:

1110111101110

0101011101001

[ your answer goes here. ]

Perform a logical OR on the following two binary strings:

1110111101110

0101011101001

[ your answer goes here. ]

Perform a logical XOR on the following two binary strings:

1110111101110

0101011101001

[ your answer goes here. ]

5.       How can hashing be used to ensure that a file you have copied from a website has been completely and accurately copied?  You should consider techniques that are in current use today for copying images and other files from servers. Provide some details with your explanation.  (10 points)