Cryptography

Question 1

Name Symetric Encryption Algorythms

Answer 1

DES/3DES
IDEA
Blowfish
Skipjack
AES

Question 2

Name DES Cipher Block

Answer 2

64bit blocks
DES Uses 16 ORs in a series to generate the cypher text. or 16 Rounds of encryption

Des actually uses 56 bit key
2-DES is 112 bit key
3-DES = 168 bit key

Question 3

Name IDEA Cipher Block

Answer 3

International Data Encryption Algo

Uses 64bit blocks like DES, but starts with 128 bit key

Question 4

Name Blowfish Cipher Block

Answer 4

Blowfish uses 64bi blocks to encrypt outpust an 80 bit key

Question 5

Name AES cipher block

Answer 5

AES Advanced Encryption Standard or Rijndael. has variable key strengths
128-bit requires 10 rounds
192 bit requires 12 rounds
256 bit requires 14 rounds

Question 6

What Cipher does WEP use

Answer 6

RC4.

This uses a variable key length ranging from 8 to 2018 bits. 1 to 256 bytes.

Question 7

Name Algorithm Block Sizeses

Answer 7

AES: Blocksize 128 and keysize 128, 192 and 256
Blowfish Blocksize 64 and keysize 32 - 448
DES Blocksize 64 and keysize 56
2DES Blocksize 64 and keysize 112
3DES Blocksize 64 and keysize 168
IDEA Blocksize 64 and keysize 128
RC2 Blocksize 64 and keysize 128
RC5 Blocksize 32, 64 of 128 and keysize 0-2048
Skipjack Blocksize 64 keysize 80
Twofish Blocksize 128 keysize is 1 - 256

Question 8

Diffie Helman Algorythm

Answer 8

A keyexchange algo to enable 2 users to excange or negotiate a secret symmetric key that will be uses subsequently for message encryption. Does not provide for message confidentiality but is extremely useful for applications such as public key infrastructure PKI.

Question 9

What is a key escrow

Answer 9

A security measure in which a cryptographic key is entrusted to a third party

Question 10

What is GAK

Answer 10

Gornment accsess to keys

GAK means that software companies will give copies of all keys to the government.

Question 11

What dies a hash function d?

Answer 11

Take a message and mix it with a hash. Gives a unique output. Generated by the sender and sent along with the message to validate the integrity and authenticity.

Question 12

A message digest is also called?

Answer 12

Hashes
Hash Value
Hash Total
Fingerprint
CRC
Checksum
Digital ID

Question 13

Name the Hashing Algorithms

Answer 13

1: SHA Secure Hashing Algorithm
SHA-160 = 160 bits using a 512 bit Block
SHA-224 = 224 bits using a 512 bit block
SHA-256 = 256 bits using a 512 bit block
SHA-384 = 384 bits using a 1024 bit block
SHA-512 = 512 bits using a 1024 bit block

2. Message Digest (2|4|5) all produce 128 bit output
3. HAVAL Hash of variable length (128, 160, 192, 224 & 256 bits)
4. HMAC Hash Message Authentication Code
5. RIPEMD - 160 - output is 160 bits, operates similar to md5

Question 14

Name the purposes of PKI

Answer 14

Publish public keys
Certify that a key is tied to an individual or entity
Provide verification of the validity of a public key

Question 15

What is a CA

Answer 15

Certificate Authority

Perform activities that make PKI function. CA Signs certificates.

Question 16

What is a RA

Answer 16

Registration Authority

Assists the CA by verifying the users identity PRIOR to issuing a certificate. DOES NOT ISSUE Certificates but facilitates the CA to do so.

Question 17

What is Key Wrapping?

Answer 17

Is to protect session key’s by wrapping a encapsulation with a KEK (Key encryption key). Can be accomplished with asymmetric or symmetric ciphers.

Question 18

What is PGP

Answer 18

Pretty Good Privacy. A protocol to secure send emails.

Question 19

email security

Answer 19

S/MIME (Secure Multipurpose Internet Mail Exension) - Authentication and Confidentiality protection. X509 certificate is used for authentication.

PEM (Privacy Enhanced Mail). Authentication,Confidentiality, Integrity, Non-repudiation. Uses RSA, DES and X.509

DKIM (Domain Key Identification Mail). Assertion that an e-mail was sent by an organization.

PGP. Pretty Good Privacy. Asymetric key system includes algorithms like RSA and IDEA.