Page 1525 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

12. B. M of N Control requires that a minimum number of agents (M)
out of the total number of agents (N) work together to perform

high-security tasks.

13. D. Output feedback (OFB) mode prevents early errors from
interfering with future encryption/decryption. Cipher Block
Chaining and Cipher Feedback modes will carry errors throughout
the entire encryption/decryption process. Electronic Code Book
(ECB) operation is not suitable for large amounts of data.

14. C. A one-way function is a mathematical operation that easily
produces output values for each possible combination of inputs but

makes it impossible to retrieve the input values.

15. C. The number of keys required for a symmetric algorithm is
dictated by the formula (n*(n–1))/2, which in this case, where n =
10, is 45.

16. C. The Advanced Encryption Standard uses a 128-bit block size,
even though the Rijndael algorithm it is based on allows a variable

block size.

17. C. The Caesar cipher (and other simple substitution ciphers) are
vulnerable to frequency analysis attacks that analyze the rate at
which specific letters appear in the ciphertext.

18. B. Running key (or “book”) ciphers often use a passage from a
commonly available book as the encryption key.

19. B. The Twofish algorithm, developed by Bruce Schneier, uses
prewhitening and postwhitening.

20. B. In an asymmetric algorithm, each participant requires two keys:

a public key and a private key.