Chapter 4 and 5: Public Key Cryptography/ Hash functions Flashcards Preview

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Flashcards in Chapter 4 and 5: Public Key Cryptography/ Hash functions Deck (44)
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1

There are two keys describe the public key and private key to the sender and recipient

sender uses recipients public key to encrypt
Recipient uses private key to decrypt

2

Public key cryptography is based on....

trap door one way function, one way meaning it is easy to compute in one direction but hard in the other direction

3

what is a digital signature

sign by encrypting with your private key, any one can verify the signature by decrypting with public key.but ONLY YOU could have signed it.

4

the general knapsack is ...

NP-complete

5

general knapsack is ..

hard to solve

6

super increasing knapsack

is easy to solve, each weight greater than the sum of all previous weights

7

what are the weakness of knapsack

Trap door, one way, lattice reduction

8

Trapdoor with knapsack is

convert SIK into general knapsack using modular arithmetic

9

one way knapsack is

general knapsack easy to encrypt, hard to solve.

10

knapsack is secure or insecure

insecure

11

RSA

2 large prime numbers, N=pq is the modulus.

12

RSA public key is

(N,e)

13

RSA private key is

d

14

what breaks the RSA

factoring the modulus breaks the RSA

15

what is Diffie Hellman (g^a and g^b)

Not used for encrypting or signing
it is based on discrete log problem

16

in diffie hellman what can trudy find to get k

trudy can find a or by then she gets the key k , if trudy can solve discrete log problem she can find a or b

17

what must you be aware of in MIM

Man in the middle, attack on diffie hellman

18

digital signature provides what

provides integrity and on repudiation

19

No non-repudiation with ..

Symmetric keys

20

what does the certificate contain

it contains the name of the user and users public key and other info. it is signed by the issuer a CA certificate authority

21

the signature on a certificate is verified using what

CA's public key.

22

what is PKI

Public key infrastructure: the stuff needed to securely use public key crypto

23

what are the three PKI trust models

Monopoly model, oligarchy model, anarchy model

24

what are the plus's in symmetric key

sped, no public key infrastructure (PKI) needed

25

what are the plus's in public key

signatures (non-repudiation)
no shared secret (but, private keys...)

26

what are the 5 things a crypto hash function must have?

Compression- output length is small
efficiencry- easy to compute for any x
one-way
wak collision resistance
strong collision resistance

27

what are the popular crypto hashes

MD5 and SHA-1

28

what is MD5

128 bit output
MD5 collisions are easy to find
invented by Rivest

29

what is SHA-1

160 but output
a U.S government standard inner workings similar to MD5

30

what is HMAC

a hashed MAC