lecture 3 Flashcards
What is cryptography?
Practice and study of techniques for secure communication in the presence of third parties called adversaries.
What is the role of cryptography in crypto currency?
Provides a mechanism for securing the rules of the cryptocurrency system in the system itself.
What is encryption?
Process of turning plain text into cypher text
what is decryption?
Process of turning cyphertext into readable plain text
What is breaking cyphertext?
Working out how to decrypt cypher text without being given the key
What is asymmetric cryptography
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
What is the purpose of ECDSA?
Generate public/ private key
What is the ECDSA process?
1) use random number as input ( remember it)
2) Do ECDSA maths to generate public key
What is the bitcoin address generated from?
ECDSA Public key
What does the bitcoin address do?
possible destination for bitcoin payment
What is the configuration of the bitcoin address?
26-35 alphanumeric characters, starts with 1,3 or bc1
What makes up a digital signature?
Message + private key
What are the 2 properties of a digital signature?
- only you can make the signature but anyone can verify it
- tied to one document: cannot be copied
What is a hash function?
algorithm that transforms arbitrary amount of input in a fixed sized output
what is hash?
value returned by hash function
what is a hash pointer?
pointer to where some information is stored together with cryptographic hash of the info at a fixed point in time
What are the 2 types of hash function?
1) basic
2) cryptographic
What are the 5 ideal functions of a cryptographic hash function?
- deterministic
- quick to compute
- can’t go backwards
- small input change makes big output change
- collusion resistant
what does SHA-256 create?
almost unique 256-bit, 64 character, 32 bytes hexadecimal number
what is the use of hash functions?
Used for proving that 2 things are the same without revealing the 2 things.
In Bitcoin, what is hash used in?
- bitcoin address
- mining process
- identifiers for transaction
etc
what are the 2 uses of hash functions outside of bitcoin?
1) authentication
2) security
What does a blockchain consist of?
a list of hashes and hash pointers
how do you create a new block?
Hashing the old block along with the transaction
What does each new block contain?
the new transaction and an encryption of the previous block
what are the 3 things that make up a bitcoin block
header, transaction count and block content
What is a Merkle tree?
A binary tree with hash pointers
