can you answer 12a and 12b plese Given the access matrix below, answer questions
ID: 3849574 • Letter: C
Question
can you answer 12a and 12b plese
Given the access matrix below, answer questions (i-iii). i. Can a process in domain D_1, grant read privileges for object F_ to a process in domain D_2? Why or why not? ii. Can a process in domain D_ revoke the write privileges of a process in domain D_1 for object F_ ? Why or why not? iii. Can a process in domain D_2 give read, write, and execute privileges for object F_2 to a process in domain D_3? Why or why not? b. Two professors are discussing the security of a distributed system in which the key used to encrypt messages is known. Professor A claims that knowing the encryption key will allow him to decrypt any message sent between nodes in the system once he determines the type of cryptography used, thus making the system insecure. Professor B claims it is possible for the system to be secure, depending on what method is used to encrypt messages. Which professor is right, and why?Explanation / Answer
12 a i) Yes, a process in domain D1 can grant read privilege for object F3 to a process in domain D2, because D1 controls D2 so, it will have the ability to authorize read/write permission to the process of domain D2.
12 a ii) No a process in domain D3 will not be able to revoke the write privilege of a process in domain D1, because D3 is only having read permission on object F3 and D3 is neither the owner of F3 nor it control D1.
12 a iii) Yes a process in domain D2 will be able to grant read, write and execute privilege on object F2 to a process in domain D3, because D2 is the owner of F2, though it didn't control D3.
12 b Professor A is right. If encryption key and the type of cryptography (algorithm) is known then their is possibility to break the encryption and get the palintext. If we are using a computationaly secure algorithm with secure encrpyption key, then it may be defficult to crack. We can use various crptographic technique to break the cipher, such as Brute force, frequency analysis etc. It may take lot of time to break the encryption, and some times it is useless because of the delay in decryption.
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