Public Key cryptography

Question 1

Why Public-Key Cryptography?

Answer 1

•key distribution – how to have secure
communications in general without having
to trust a KDC with your key
•digital signatures – how to verify a
message comes intact from the claimed
sender

Question 2

what is a trapdoor function?

Answer 2

Easy to compute in one direction . but difficult to compute the other way unless some special information is given