Quiz 1

Question 1

What makes a cryptographically secure hash function?

Answer 1

1. Collision resistance
2. Hiding/Pre-Image resistance
3. Puzzle friendliness (hard to find x given y)

Question 2

Hash Pointers

Answer 2

Pointer to where some data is stored, cryptographic hash of info.

Question 3

Hash Function

Answer 3

Mathematical functions that satisfy the following three properties:
• Inputs can be any size (not-fixed);
• Outputs are fixed-size (we’ll generally employ a hash function such as SHA-256 that has an output size of 256 bits)
• Efficiently computable, i.e., the mapping should be efficiently (in polynomial time in terms of the input size) computable

Question 4

Blockchain

Answer 4

Linked list of hash pointers, each block contains header of previous block

Question 5

Merkle Tree

Answer 5

Binary tree of hash pointers

Question 6

Digital Signature

Answer 6

Private key to encrypt/sign, public key to decrypt

Question 7

Symmetric encryption

Answer 7

Single key encryption

Question 8

Asymmetric/Public key encryption

Answer 8

Public key used to encrypt, private key used to decrypt