Flashcards in Chapter 4 and 5: Public Key Cryptography/ Hash functions Deck (44)
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
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
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.
the general knapsack is ...
general knapsack is ..
hard to solve
super increasing knapsack
is easy to solve, each weight greater than the sum of all previous weights
what are the weakness of knapsack
Trap door, one way, lattice reduction
Trapdoor with knapsack is
convert SIK into general knapsack using modular arithmetic
one way knapsack is
general knapsack easy to encrypt, hard to solve.
knapsack is secure or insecure
2 large prime numbers, N=pq is the modulus.
RSA public key is
RSA private key is
what breaks the RSA
factoring the modulus breaks the RSA
what is Diffie Hellman (g^a and g^b)
Not used for encrypting or signing
it is based on discrete log problem
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
what must you be aware of in MIM
Man in the middle, attack on diffie hellman
digital signature provides what
provides integrity and on repudiation
No non-repudiation with ..
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
the signature on a certificate is verified using what
CA's public key.
what is PKI
Public key infrastructure: the stuff needed to securely use public key crypto
what are the three PKI trust models
Monopoly model, oligarchy model, anarchy model
what are the plus's in symmetric key
sped, no public key infrastructure (PKI) needed
what are the plus's in public key
no shared secret (but, private keys...)
what are the 5 things a crypto hash function must have?
Compression- output length is small
efficiencry- easy to compute for any x
wak collision resistance
strong collision resistance
what are the popular crypto hashes
MD5 and SHA-1
what is MD5
128 bit output
MD5 collisions are easy to find
invented by Rivest
what is SHA-1
160 but output
a U.S government standard inner workings similar to MD5