lecture 3

Question 1

What is cryptography?

Answer 1

Practice and study of techniques for secure communication in the presence of third parties called adversaries.

Question 2

What is the role of cryptography in crypto currency?

Answer 2

Provides a mechanism for securing the rules of the cryptocurrency system in the system itself.

Question 3

What is encryption?

Answer 3

Process of turning plain text into cypher text

Question 4

what is decryption?

Answer 4

Process of turning cyphertext into readable plain text

Question 5

What is breaking cyphertext?

Answer 5

Working out how to decrypt cypher text without being given the key

Question 6

What is asymmetric cryptography

Answer 6

A pair of keys is used that are mathematically related but not identical, public key can be shared with everyone, private key known only to you

Question 7

What is the purpose of ECDSA?

Answer 7

Generate public/ private key

Question 8

What is the ECDSA process?

Answer 8

1) use random number as input ( remember it)
2) Do ECDSA maths to generate public key

Question 9

What is the bitcoin address generated from?

Answer 9

ECDSA Public key

Question 10

What does the bitcoin address do?

Answer 10

possible destination for bitcoin payment

Question 11

What is the configuration of the bitcoin address?

Answer 11

26-35 alphanumeric characters, starts with 1,3 or bc1

Question 12

What makes up a digital signature?

Answer 12

Message + private key

Question 13

What are the 2 properties of a digital signature?

Answer 13

• only you can make the signature but anyone can verify it
• tied to one document: cannot be copied

Question 14

What is a hash function?

Answer 14

algorithm that transforms arbitrary amount of input in a fixed sized output

Question 15

what is hash?

Answer 15

value returned by hash function

Question 16

what is a hash pointer?

Answer 16

pointer to where some information is stored together with cryptographic hash of the info at a fixed point in time

Question 17

What are the 2 types of hash function?

Answer 17

1) basic
2) cryptographic

Question 18

What are the 5 ideal functions of a cryptographic hash function?

Answer 18

• deterministic
• quick to compute
• can’t go backwards
• small input change makes big output change
• collusion resistant

Question 19

what does SHA-256 create?

Answer 19

almost unique 256-bit, 64 character, 32 bytes hexadecimal number

Question 20

what is the use of hash functions?

Answer 20

Used for proving that 2 things are the same without revealing the 2 things.

Question 21

In Bitcoin, what is hash used in?

Answer 21

• bitcoin address
• mining process
• identifiers for transaction
  etc

Question 22

what are the 2 uses of hash functions outside of bitcoin?

Answer 22

1) authentication
2) security

Question 23

What does a blockchain consist of?

Answer 23

a list of hashes and hash pointers

Question 24

how do you create a new block?

Answer 24

Hashing the old block along with the transaction

Question 25

What does each new block contain?

Answer 25

the new transaction and an encryption of the previous block

Question 26

what are the 3 things that make up a bitcoin block

Answer 26

header, transaction count and block content

Question 27

What is a Merkle tree?

Answer 27

A binary tree with hash pointers