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Cryptography correct answers Transmitting messages and transactions securely against third party adversaires
When we want to make a secure transactions, following has to occur(4) correct answers 1) message comes from right sender
2)1) message comes from right sender is not read by anyone else
3) Message is not altered
4) message is delivered to the right receiver
Hashing correct answers -form of cryptography, used for checksum
-transforms any text to an arbitrary length
-used extensively in blockshain and is used to confirm that file was not corrupted and for message authentication
Encryption correct answers -technique to make sure message is not ready by anyone else -symmetric and asymmetric
Is hashing one way or two way? correct answers one way
Does hashing randomly reshuffle text? correct answers No, same input produces same output
SHA-256 hash correct answers -takes any text and transforms into a string of 256 bits of 0 and 1
How many possible combinations does a SHA-256 hash have? correct answers 2^256 = 1.15x10^77
We want have a hashing function that.....(5) correct answers 1)easy to compute, but not to decrypt
2)changes when plaintext changes
3)always produces the same hash from same input 4)impossible to have collision
5)needs to be fast, but not too fast
What is a collision attack? correct answers Two plaintext's with the same hash What are the main hashing functions?(4) correct answers 1) MD: produces 128-bit hash values(Not used anymore)
2)SHA1: produces 160-bit hash values -made by NASA and not really used anymore
3) SHA2L current standard for hashing - SHA256 and SHA512 are the most used, produced 64 and 128 strings, respectively
4) SHA3 is most recent hashing function, uses a different structure then any of the others
Rainbow Tables correct answers -databases of common passwords and related hash
Salt correct answers -extra string of characters in front of password to make it unique
When is a hash collision resistant? correct answers -if the fastest way to find a collision is to do it
through brute force
Birthday Paradox correct answers Based on probability with 23 people 50% chance 2 will have same birthday
Preimage attack correct answers Designing a method that, given a hash, finds a plaintext that generates the hash
Birthday paradox does not apply here
How can quantum computers crack encryptions? correct answers -using Shor's algorithm
What are the two main types of encryption algorithms? correct answers 1) Symmetric Key Encryption: common secret key is exchanged between sender and the received (MOST USED)
2) Asymmetric kept encryption: only receiver has key to decipher content
Plaintext correct answers Input message that you want to encrypt
Ciphertext correct answers The encrypted message
Advanced Encryption Standard(AES) correct answers Most common symmetric key encryption
-used worldwide
What are the pros of symmetric key encryption? (2) correct answers 1) common key doesn't have
to be very long 128-256 bits 2) very fast What are the cons of symmetric key encryption? (2) correct answers 1) how do you safely share common key
2) Need a key for each pair of players
Intuition of asymmetric key encryption(4) .... the steps.... correct answers 1) receivers creates lock(PUBLIC KEY) and and a key (PRIVATE KEY)
2) receiver sends lock to sender
3) sender uses lock to encrypt plaintext and send the ciphered text
4)receiver decrypts cipher-text using key
What is the main advantage of asymmetric key over symmetric? correct answers -every user needs to have only one public key , however it needs long keys which make transmissions slow and not as secure
Signing a message correct answers -a signature message send with message to verify identity
The RSA algorithm relies on these assumptions(5): correct answers 1) Factoring (finding p and q) is hard
2)finding random prime numbers p and q are easy
3)multiplying prime numbers is easy
4)module exponential ion is easy
5)given p and q, modular root extraction is easy, but without it, is very hard
What is the first and most used asymmetric key encryption? correct answers RSA
What does the security of private keys rely on? correct answers How hard it is to factor large numbers
Elliptic Curve Cryptography correct answers -used by most software packages and also by bitcoin to make sure transactions are secure and to prevent double spending -use on the properties of the elliptic curve and modular arithmetic to generate a pseudo-random numbers to encrypt and decrypt
-relies on decimeter logarithm problem -much smaller keys than RSA (MAIN ADVANTAGE)
What you need to encrypt/decrypt with elliptic curve(3) correct answers -domain parameters -private key
-public key
What is a ledger? (Blockchain) correct answers Established and transfers ownership of an asset where consensus(approval) is decentralized -currency
-financial securities -real assets
Cryptography correct answers Transmitting messages and transactions securely against third party adversaires
When we want to make a secure transactions, following has to occur(4) correct answers 1) message comes from right sender
2)1) message comes from right sender is not read by anyone else
3) Message is not altered
4) message is delivered to the right receiver
Hashing correct answers -form of cryptography, used for checksum
-transforms any text to an arbitrary length
-used extensively in blockshain and is used to confirm that file was not corrupted and for message authentication
Encryption correct answers -technique to make sure message is not ready by anyone else -symmetric and asymmetric
Is hashing one way or two way? correct answers one way
Does hashing randomly reshuffle text? correct answers No, same input produces same output
SHA-256 hash correct answers -takes any text and transforms into a string of 256 bits of 0 and 1
How many possible combinations does a SHA-256 hash have? correct answers 2^256 = 1.15x10^77
We want have a hashing function that.....(5) correct answers 1)easy to compute, but not to decrypt
2)changes when plaintext changes
3)always produces the same hash from same input 4)impossible to have collision
5)needs to be fast, but not too fast
What is a collision attack? correct answers Two plaintext's with the same hash What are the main hashing functions?(4) correct answers 1) MD: produces 128-bit hash values(Not used anymore)
2)SHA1: produces 160-bit hash values -made by NASA and not really used anymore
3) SHA2L current standard for hashing - SHA256 and SHA512 are the most used, produced 64 and 128 strings, respectively
4) SHA3 is most recent hashing function, uses a different structure then any of the others
Rainbow Tables correct answers -databases of common passwords and related hash
Salt correct answers -extra string of characters in front of password to make it unique
When is a hash collision resistant? correct answers -if the fastest way to find a collision is to do it
through brute force
Birthday Paradox correct answers Based on probability with 23 people 50% chance 2 will have same birthday
Preimage attack correct answers Designing a method that, given a hash, finds a plaintext that generates the hash
Birthday paradox does not apply here
How can quantum computers crack encryptions? correct answers -using Shor's algorithm
What are the two main types of encryption algorithms? correct answers 1) Symmetric Key Encryption: common secret key is exchanged between sender and the received (MOST USED)
2) Asymmetric kept encryption: only receiver has key to decipher content
Plaintext correct answers Input message that you want to encrypt
Ciphertext correct answers The encrypted message
Advanced Encryption Standard(AES) correct answers Most common symmetric key encryption
-used worldwide
What are the pros of symmetric key encryption? (2) correct answers 1) common key doesn't have
to be very long 128-256 bits 2) very fast What are the cons of symmetric key encryption? (2) correct answers 1) how do you safely share common key
2) Need a key for each pair of players
Intuition of asymmetric key encryption(4) .... the steps.... correct answers 1) receivers creates lock(PUBLIC KEY) and and a key (PRIVATE KEY)
2) receiver sends lock to sender
3) sender uses lock to encrypt plaintext and send the ciphered text
4)receiver decrypts cipher-text using key
What is the main advantage of asymmetric key over symmetric? correct answers -every user needs to have only one public key , however it needs long keys which make transmissions slow and not as secure
Signing a message correct answers -a signature message send with message to verify identity
The RSA algorithm relies on these assumptions(5): correct answers 1) Factoring (finding p and q) is hard
2)finding random prime numbers p and q are easy
3)multiplying prime numbers is easy
4)module exponential ion is easy
5)given p and q, modular root extraction is easy, but without it, is very hard
What is the first and most used asymmetric key encryption? correct answers RSA
What does the security of private keys rely on? correct answers How hard it is to factor large numbers
Elliptic Curve Cryptography correct answers -used by most software packages and also by bitcoin to make sure transactions are secure and to prevent double spending -use on the properties of the elliptic curve and modular arithmetic to generate a pseudo-random numbers to encrypt and decrypt
-relies on decimeter logarithm problem -much smaller keys than RSA (MAIN ADVANTAGE)
What you need to encrypt/decrypt with elliptic curve(3) correct answers -domain parameters -private key
-public key
What is a ledger? (Blockchain) correct answers Established and transfers ownership of an asset where consensus(approval) is decentralized -currency
-financial securities -real assets
