Crypto ch 8

Question 1

Asymmetric cipher

Answer 1

Crypto algorithms that use two different keys-1 key to encrypt and another to decrypt. Also called public key crypto

Question 2

Chap

Answer 2

Challenge hand shake authentication protocol

A authentication protocol that PERIODICALLY reauthenticates

Question 3

Collision

Answer 3

When 2 different inputs into crypto hash produce the same output, this is known as a collision.

Question 4

Cryptographic hash

Answer 4

A function that is 1 way (non reversible) has a fixed length output and is collision resistant.

Question 5

PRNG

Answer 5

A pseudo-random number generator is and algorithm used to generate a number that is sufficiently random for cryptographic purposes.

Question 6

Rainbow table

Answer 6

A table precomputed hashes used to guess passwords by searching for the hash of a password.

Question 7

Salt

Answer 7

Bits added to a hash to make it resistant to rainbow table attacks.

Question 8

Symmetric cipher

Answer 8

Any cryptographic algorithm that uses the same key to encrypt and decrypt. DES, AES, and Blowfish are examples
Skl and taclanes
Gost

Question 9

X.509

Answer 9

X.509 standard is the most widely used standard for digital certificates

Question 10

Cryptool 1.4.40
Md-message digest md5 56bits has a high rate of collision
2 diff inputs has same output

Sha-has different bits

Answer 10

Hex value based on integrity

Question 11

Cast
3des*168 bits
Blowfish/2fish/Bruce schneir 64bit Blck 
Rcx(rc4/rc5)*2,048bits
Aes * by joan daemen/ Vincent rijmen 128/192/256 (hard drive)
Idea
Des*
Skipjack,safer,safer+secpent

Sym 
Same key encrypt to decrypt 
Out of band delivery, different times
Otr-over the air rekey 
Great for bulk encryption

Answer 11

-Different-Hellman founder pub/Pvt key
E-lliptic curve cryp-sim to rsa strng shrt Mobile
-ElgMal-transmitting dig sig and key exchanges
-Ecdhe
-Rsa-widely used .ron rivest, adi Shamir, Leonard adleman public key uses large integers

Asym
Strong and slower

Question 12

SHA

Answer 12

Secure hash algorithm-provides hash value that can be used and encryption protocol

160bithash

Sha2-224,256,334,512
Sha3-

None as keccak

Question 13

Key stretching

Answer 13

Password based key function derevation 2

Making the key stronger

Question 14

Crypto-analysis methods

Answer 14

• Brute force
• frequency analysis
• known plain text
• chosen plain text
• related key attack
• birthday attack
• other methods
• exploiting human error
• wi-if encryption

Question 15

Cryptographic systems

Answer 15

Confidentiality & strength
Integrity
When to encrypt
Digital signatures
Authentication 
Nonrepudiation 
Key features

Question 16

Pgp

Answer 16

Proprietary and is (pretty good privacy)

Question 17

Tunneling protocols

Answer 17

PPTP
L2f
Tunneling protocol

Question 18

FIPS

Answer 18

Federal information processing standards

Question 19

PkI

Scaling up security

Answer 19

Two way, asymmetric system w 4 main components

• certificate authority -issue/revoking/distro certs
• registration authority-take a req on behalf and send to ca. Can distro keys, valid indent
• rsa
• digital certificates
• lra-local registration authority

Question 20

Certificate revocation list

Answer 20

Revoking before it expires

Crl-certificate revoc list
Ocsp-online certificate status protocol
Repository-database our database server where the certs are stored

Question 21

Trust models with pki

Answer 21

• Hierarchical -aka tree at the top provides all information
• bridge-p2p relationships exists between root ca’s
• mesh-expands bridge model by supporting multiple paths and multiple roots
• hybrid-can use the capabilities of any or all of the structures discussed in previous sections