P2L5 Intro to Cryptograph

Question 1

Attacks on Encryption

Answer 1

• Brute-force attack (try all keys)
• Crypto-analysis - analyze algorithms and data
• Implementation attack - side channel analysis, example observer power consumption of crypto system to determine value
• social engineering

Question 2

Encryption

Answer 2

One-to-one mapping which creates cipher

Question 3

What should be kept secret?

Answer 3

Encryption key

Question 4

Types of Cryptography

Answer 4

Secret Key (one key for encrypt/decrypt)
Public Key(two keys, public for encryption, private for decryption. Also use for signing.
Hash Function - data of any size transformed to fixed length output (128-512 bits)

Question 5

Hash Function Features

Answer 5

Easy to compute H(m)
H(m), no easy way to find m
one-way function
Given m1, it is computationally infeasible to find m2!=m1 such that H(m1)=H(m2) (weak collision resistant)
Or
Computational infeasible to find m1!=m2 s.t. H(m1) = H(m2)
(strong collision resistant)