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Which of the following algorithms uses three different keys to encrypt the plain text?

  1. Skipjack
  2. AES
  3. Blowfish
  4. 3DES

Answer(s): D

Explanation:

3DES
https://en.wikipedia.org/wiki/Triple_DES
Triple DES (3DES) has a three different keys with same size (56-bit).
Incorrect answers:
AES. For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.
Blowfish. Blowfish has a 64-bit block size and a variable key length from 32 bits up to 448 bits. Skipjack. Skipjack uses an 80-bit key to encrypt or decrypt 64-bit data blocks.



Original, unencrypted information is referred to as ____________.

  1. text
  2. plaintext
  3. ciphertext
  4. cleartext

Answer(s): B

Explanation:

plaintext https://en.wikipedia.org/wiki/Plaintext
In cryptography, plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. Cleartext usually refers to data that is transmitted or stored unencrypted ("in clear").



Which of the following is a block cipher?

  1. AES
  2. DH
  3. RC4
  4. RSA

Answer(s): A

Explanation:

AES
https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
AES is a subset of the Rijndael block cipher developed by two Belgian cryptographers, Vincent Rijmen and Joan Daemen, who submitted a proposal to NIST during the AES selection process

Incorrect answers:
RC4. RC4 (Rivest Cipher 4 also known as ARC4 or ARCFOUR meaning Alleged RC4, see below) is a stream cipher.
DH. Diffie–Hellman key exchange is a method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after Whitfield Diffie and Martin Hellman.
RSA. RSA (Rivest–Shamir–Adleman) is one of the first public-key cryptosystems and is widely used for secure data transmission.



You are trying to find a modern method for security web traffic for use in your company's ecommerce web site. Which one of the following is used to encrypt web pages and uses bilateral authentication?

  1. AES
  2. SSL
  3. TLS
  4. 3DES

Answer(s): C

Explanation:

TLS
https://en.wikipedia.org/wiki/Mutual_authentication
Mutual authentication or two-way authentication refers to two parties authenticating each other at the same time, being a default mode of authentication in some protocols (IKE, SSH) and optional in others (TLS). By default the TLS protocol only proves the identity of the server to the client using X.509 certificate and the authentication of the client to the server is left to the application layer. TLS also offers client - to-server authentication using client-side X.509 authentication. As it requires provisioning of the certificates to the clients and involves less user-friendly experience, it's rarely used in end-user applications.






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