5. ×Key Distribution : Negotiation ×Key Management : N*(N-1)/2

7. In 1978, Knapsack System, a public key cryptosystem, was raised by Merkle and Hellman based on its intractability

16. In 1978, RSA System, a public key cryptosystem, was raised by Rivest, Shamire and Adleman based on Decomposition of BigNumber and Detection of Primes

21. Why must we need authentication ?

22. Attack to Information Security : Passive Attack : Cut-Out & Analysis Active Attack : Forge, Resend, Distort, Reject Denial : deny the info sender sends

23. Defense : Passive Attack : Encryption Active Attack, Denial : Digital Signature

24. Reliability Unforgeability Nonduplication Unchangeability Nonrepudiation

25. Hash Encryption (RSA)Decryption (RSA) AU TH EN TIC ATI ON