1. c1 is received with error will only affect p1 and p2, as long as c2 and c3 are received correctly, p3 will be valid plaintext 2. Complete mediation. Every access to the disk code must be checked for authority. 3. Psychological acceptability. It is not easy to use, especially for those forgetful people 4. A)
Stored: mostly on checking user inputs, make sure only safe inputs are stored in database. Output sanitation is also important to guarantee that malicious code are not downloaded by users.
Reflected: mostly on output sanitation, make sure that website doesn't reveal any user input. Besides, input validation is also important to reject malicious inputs.
B)
Input sanitation is used to validate user inputs, all user inputs must be checked before execution or stored in database.
Output sanitation is used to detect and reject malicious code from being downloaded by users or user information being revealed. 5. PK system is too costly and complicated to use. It is much more efficient (in terms of time and space) to use it to exchange symmetric key secretly. 6. A)
(C, {P}) !dom (C,{R}) so Jill can’t read the document.
(C, {R}) !dom (C,{P}) so Jill can’t write the document.
B)
(T, {Q, P}) !dom (S,{R,P}) so Paul can’t read the document.
(S, {R, P}) !dom (S,{Q,P}) so Paul can’t write the document. 7. Complete mediation. Access to the signal tower must be checked for authority.
第二个不确定
Least common mechanism. Base station is a common mechanism to connect to the mobile network, it must but trustworthy, otherwise others are affected. 8. Since it says that multiple sessions can open at the same time. Harry can any how send a possible nonce to Bob at first, then Bob will reply his nonce with the encrypted version of Harry’s nonce. Then Harry can open a new connection with Bob and use the nonce Bob returned to him as his nonce, then Bob