# RTU Question Papers B Tech CSE 8th Sem Information

# System and Security 2012

**Unit-I **

1. (a) State and prove Eulers Theorem.

(b) Discuss Chinese remainder theorem in details.

**OR
**

1. (a) Write Short Note on

1.Group

2.Field

3.Ring

4.Galois Field

**Unit- II **

2. (a) Differentiate the following

1. Active and Passive attach

2.Diffusion and confusion.

(b) Describe the following transposition techniques with suitable examples

1. Vernam Cipher 2. Simple columnar Transposition Technique.

**OR
**

2. (a) How many keys are required for secure communication among 1000 person if

1. symmetric key encryption algorithm is used

2. Asymmetric key encryption algorithm is used

(b) Describe the DES algorithm in Details

**Unit- III
**

3. (a) Describe the diffie-Hellman key exchange algorithm in details. Also discuss the “man in the middle attach” problem associated with algorithm.

**OR**

3. (a)Perform the Encryption and decryption using RSA algorithm. p=3 Q= 11 E= 7 and M=5

(b)Public Key authority and Public key Certificate.

**Unit- IV
**

4. (a)Describe the Digital Signature. show how signing and verification is done using DSS.

(b) Give the difference between hash and message authentication code.

**OR
**

4. (a)Explain the MD5 Algo.

(b)Two way public key and one-way public Key

**Unit- V
**

5. (a) Describe How PGP provides confidentiality and authentication services for E-mail applications in Internet.

(b) S.Mine and X.509 Certificate

**OR
**

5. (a) Approaches for the intrusion detection and Authentication header