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