System Analysis and Design
531. Filtering of packets by firewall based on a router has facilities to
- prevent access to internet to some clients in the intranet
- prevent access at certain specified times
- filter packets based on source or destination IP address
- prevent access by certain users of the internet to other specified users of the internet
- i, iii
- i, ii, iii
- i, ii, iii, iv
- ii, iii, iv
Correct answer: (B)
i, ii, iii
532. By encryption of a text we mean
- compressing it
- expanding it
- scrambling it to preserve its security
- hashing it
Correct answer: (C)
scrambling it to preserve its security
533. Encryption can be done
- only on textual data
- only on ASCII coded data
- on any bit string
- only on mnemonic data
Correct answer: (C)
on any bit string
534. DES works by using
- permutation and substitution on 64 bit blocks of plain text
- only permutations on blocks of 128 bits
- exclusive ORing key bits with 64 bit blocks
- 4 rounds of substitution on 64 bit blocks with 56 bit keys
Correct answer: (A)
permutation and substitution on 64 bit blocks of plain text
535. Triple DES
- is a symmetric key encryption method
- guarantees excellent security
- is implementable as a hardware VLSI chip
- is public key encryption method with three keys.
Correct answer: (ii)
guarantees excellent security
536. DES and public key algorithm are combined
- to speed up encrypted message transmission
- to ensure higher security by using different key for each transmission
- as a combination is always better than individual system
- as it is required in e-Commerce
- i and ii
- ii and iii
- iii and iv
- i and iv
Correct answer: (A)
i and ii
537. Hashed message is signed by a sender using
- his public key
- his private key
- receiver's public key
- receiver's private key
Correct answer: (B)
his private key
538. In SET protocol a customer sends a purchase order
- encrypted with his public key
- in plain text form
- encrypted using Bank's public key
- using digital Signature system
Correct answer: (D)
using digital Signature system
539. In NetBill's protocol for small payments for internet services
- Key to decrypt information is sent to customer by NetBill only when there is enough amount in debit account
- The vendor supplies the key to NetBill server when he receives payment
- Checksum of encrypted information received by customer is attached to his payment order
- Vendor does not encrypt information purchased by customer
- i, ii
- i, ii, iii
- i, ii, iii, iv
- i, ii, iv
Correct answer: (B)
i, ii, iii
540. In Electronic cash payment
- a customer withdraws “coins” in various denominations signed by the bank
- the bank has a database of issued coins
- the bank has a database of spent coins
- the bank cannot trace a customer
- i, ii
- i, ii, ii
- i, ii, iii, iv
- ii, iii, iv
Correct answer: (B)
i, ii, ii