Digital Signatures

Question 1

Gen(): A randomized key generation function that outputs a _______

Answer 1

public, private key pair

Question 2

Outputs a signature

Answer 2

Sign(messsage, secret_key)

Question 3

Check if signature is valid signature of message

Answer 3

Verify(signature, message, public_key)

Question 4

Computationally difficult to forge

Answer 4

Digital signatures

Question 5

publish public keys in a public forum

Answer 5

public announcement of public keys

Question 6

trusted authority maintains directory mapping names to public keys

Answer 6

public directory

Question 7

entity registers keys in some way

Answer 7

public directory

Question 8

binds certificate to person

Answer 8

certificate authority

Question 9

binds public key to user

Answer 9

certificates

Question 10

certificate serial number, subject name, issuer name, extensions, version, etc.

Answer 10

X.509 certificate

Question 11

issuer name, this update date, next update date, revoked certificate, etc

Answer 11

certificate revocation list

Question 12

Ensure expiration time is checked

Answer 12

limiting damage in certificates

Question 13

If authority’s private key is compromised, everything is vulnerable

Answer 13

problems with certificates

Question 14

Depend on certificate authority, big trusted entity

Answer 14

Problems with certificates

Question 15

Need to acquire a certificate

Answer 15

makes anonymity difficult, requires handshaking

Question 16

certificate must be validated

Answer 16

problems with certificates