('Dawn Song', 'Midterm 1', '(solution)') Spring 2012

E 1 point trusted boot can be used to detect that the

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Unformatted text preview: s used to provide TRUST (i.e., storing secrets and attesting the values of PCR’s. TPM’s are in fact Page 9 extremely slow and if they are used for hard drive encryption (assuming this is even possible), they will actually slow it down a lot. (e) (1 point) Trusted boot can be used to detect that the operating system kernel has been modified by a virus. ◦ True ◦ False Answer: This question was not graded so everyone will receive 1 point for this question regardless of their answer. (f) (1 point) Trusted boot can be used to detect that the hardware has been tampered with. ◦ True ◦ False Answer: False (g) (1 point) A user with root/administrator privileges can read the internal memory of a TPM, but a user without root/administrator privileges cannot. ◦ True ◦ False Answer: False (h) (1 point) With DRTM (Dynamic Root of Trust Measurement), the BIOS is measured (i.e., its cryptographic hash is computed and stored in a PCR). ◦ True ◦ False Answer: False Page 10 5. (10 points) Cryptography (a) (1 point) There is a mathematical proof that factoring large numbers is computationally infeasible (i.e., it takes too much time). ◦ True ◦ False Answer: False. Factoring is considered hard because it is a well known problem that no one knows how to solve efficiently. (b) (1 point) How does a MAC (Message Authentication Code) differ from symmetric encryption? Note: To invert means to compute the input given the output. (circle all that apply) ◦ It doesn’t. ◦ A MAC has a pair of keys (public and private) and symmetric encryption does not. ◦ A MAC has a single key and symmetric encryption does not. ◦ Symmetric encryption has a pair of keys (public and private) a MAC does not. ◦ Symmetric encryption has a single key and a MAC does not. ◦ Symmetric encryption has a fixed-size output and a MAC does not. ◦ A MAC has a fixed-size output and symmetric encryption does not. ◦ Given the key(s), it is always feasible to invert a MAC, but it is not always feasible to invert symmetric encryption....
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