Lecture 4

Why is asymmetric encryption called “asymmetric”?Why is it also called PKC?

What key/s is/are used in asymmetric encryption?

What key/s is/are used in asymmetric decryption?

What is a challenge when using asymmetric encryption?

What is Diffie-Hellman key exchange?What problem does it solve?How does it work?

What does “public” mean in this context?Why can one key in a pair be made public?

What does “private” mean in this context?

What are three misconceptions about PKC?Why are they incorrect?

What is RSA?Why is it so named?

What operation does it use?Why does that operation provide security?

How is an RSA modulus generated?What would be needed to “crack” it?

RSA is just a monoalphabetic substitution – why can’t frequency analysis “crack” it?

Why is it not practical to use RSA to encrypt large amounts of general-purpose data?

How is RSA typically used when a large amount of data is to be encrypted and sent?

Which key is used by the sender in this context?Which key is used by the recipient?Why?

How can a trusted third party help solve a key management problem?

What are some risks when using a trusted third party?

What is a certificate in this context?What does it contain?Who creates it?

How can a certificate be verified?What is needed?

What is a self-signed certificate?Why is it needed?

Which modes of operation can be used with asymmetric encryption?

Lecture 5

What is the generic authentication protocol?What does it require?

How many messages could be created (ignoring practical length restrictions)?

How many fixed-length MACs (or hashes) could be generated by a MAC (or hash) function?

What is a collision in this context?

Why is ciphertext not a reliable authenticator?

What is a MAC?What services does it provide?

What is/are the input/s to a MAC function?

How does the recipient of a message with a MAC authenticate the message?

How can a symmetric block cipher be used to generate a MAC?In which mode?

What is a hash function?What services does it provide?

What is/are the input/s to a hash function?

Why must a hash value be encrypted?

What is the result of symmetric encryption of a hash?

continued …

What is the result of asymmetric encryption of a hash?

Which key/s is/are used to asymmetrically encrypt a hash?To decrypt?

What is SHA-1?What is the length of its output?How likely is a collision onto an SHA-1 value?

What is an HMAC?How is it different from an older form of MAC?Why the change?

Whatis a digital signature?How is a DSS digital signature produced usingthe RSA approach?What does a digital signature provide that a MAC doesnot?Why?