Non-repudiation

Question 1

Non-repudiation

Answer 1

You can’t deny what you’ve said
-There’s no taking it back

Question 2

Sign a contract

Answer 2

-your signature adds non-repudiation
-you really did sign the contract
-others can see your signature

Question 3

Adds a different perspective for cryptography

Answer 3

-proof of integrity
-proof of origin, with high assurance of authenticity

Question 4

Proof of integrity

Answer 4

-verify data does not change
-the data remains accurate and consistent

Question 5

In cryptography, we use a hash

Answer 5

-represent data as a short string of text
-a message digest, a fingerprint

Question 6

If the data changes, the hash changes

Answer 6

-if the person changes, you get a different fingerprint

Question 7

Doesn’t necessarily associate data with an individual

Answer 7

-only tells you if the data has changed

Question 8

If the hash is different, something has changed

Answer 8

-the data integrity has been compromised

Question 9

Prove the source of the message

Answer 9

-authentication

Question 10

Proof of origin

Answer 10

-prove the message was not changed
-integrity

Question 11

Make sure the signature isn’t fake

Answer 11

-non-repudiation

Question 12

Sign with the private key

Answer 12

-the message doesn’t need to be encrypted
-nobody else can sign this

Question 13

Verify the public key

Answer 13

-any change to the message will invalidate the signature

Question 14

Creating a digital signature

Answer 14

-alice is sending a message to bob that says your hired bob, she will provide a digital signature before she sends it - the first thing that happens when she clicks that checkbox for the digital signature is that a hashing algorithm creates a hash of the plain text. Once the hash is created we now need to have some way to verify that it came from alice, and since alice is the only one with her private key, we are going to encrypt that hash with alice’s private key, take that encrypted hash , send it along with the plain text so that bob is going to receive a message that says you’re hired bob and then attached to that message is a digital signature

Question 15

Verifying a digital signature

Answer 15

-bob is going to use alice’s public key which is a key available to anyone and he is going to exam the digital signature and decrypt it using that public key. Once that decryption takes place we have the original hash that was created of that plain text message. Bob now wants to see if the hash that was in that digital signature matches the hash of what he received. He is going to take the original plain text, run it through the same hashing algorithm to come with a hash of what he received. He can now compare the hash and if that matches he knows the info is exactly what was sent and it was sent from alice.