Solutions - Network Security Essentials - Stallings - 4th ed - Chapter 4

4.1 “We are under great pressure, Holmes.” Detective Lestrade looked nervous.“We have
learned that copies of sensitive government documents are stored in computers of one
foreign embassy here in London. Normally these documents exist in electronic form only
on a selected few government computers that satisfy the most stringent security requirements.
However, sometimes they must be sent through the network connecting all government
computers. But all messages in this network are encrypted using a top secret
encryption algorithm certified by our best crypto experts. Even the NSA and the KGB
are unable to break it.And now these documents have appeared in hands of diplomats of
a small, otherwise insignificant, country.And we have no idea how it could happen.”
“But you do have some suspicion who did it, do you?” asked Holmes.
“Yes, we did some routine investigation.There is a man who has legal access to
one of the government computers and has frequent contacts with diplomats from the
embassy. But the computer he has access to is not one of the trusted ones where these
documents are normally stored. He is the suspect, but we have no idea how he could
obtain copies of the documents. Even if he could obtain a copy of an encrypted document,
he couldn’t decrypt it.”
“Hmm, please describe the communication protocol used on the network.”
Holmes opened his eyes, thus proving that he had followed Lestrade’s talk with an
attention that contrasted with his sleepy look.
“Well, the protocol is as follows. Each node N of the network has been assigned
a unique secret key Kn. This key is used to secure communication between the node
and a trusted server.That is, all the keys are stored also on the server. User A, wishing
to send a secret message M to user B, initiates the following protocol:
1. A generates a random number R and sends to the server his name A, destination
B, and E(Ka, R).  Get this solution


2. Server responds by sending E(Kb, R) to A.
3. A sends E(R,M) together with E(Kb, R) to B.
4. B knows Kb, thus decrypts E(Kb, R) to get R and will subsequently use R to
decrypt E(R,M) to get M.
You see that a random key is generated every time a message has to be sent. I admit
the man could intercept messages sent between the top secret trusted nodes, but I see
no way he could decrypt them.”
“Well, I think you have your man, Lestrade. The protocol isn’t secure because
the server doesn’t authenticate users who send him a request. Apparently designers
of the protocol have believed that sending E(Kx,R) implicitly authenticates user X as
the sender, as only X (and the server) knows Kx. But you know that E(Kx, R) can be
intercepted and later replayed. Once you understand where the hole is, you will
be able to obtain enough evidence by monitoring the man’s use of the computer he
has access to. Most likely he works as follows: After intercepting E(Ka, R) and
E(R,M) (see steps 1 and 3 of the protocol), the man, let’s denote him as Z, will continue
by pretending to be A and...
Finish the sentence for Holmes.

4.2 There are three typical ways to use nonces as challenges. Suppose Na is a nonce generated
by A,A

Describe situations for which each usage is appropriate. Get this solution


4.3 Show that a random error in one block of ciphertext is propagated to all subsequent
blocks of plaintext in PCBC mode (see Figure F.2 in Appendix F). Get this solution


4.4 Suppose that, in PCBC mode, blocks Ci and Ci 1 are interchanged during transmission.
Show that this affects only the decrypted blocks Pi and Pi 1 but not subsequent blocks. Get this solution


4.5 In addition to providing a standard for public-key certificate formats, X.509 specifies
an authentication protocol.The original version of X.509 contains a security flaw.The
essence of the protocol is
A B: A {tA, rA, IDB}
B A: B {tB, rB, IDA, rA}
A B: A {rB}
where tA and tB are timestamps, rA and rB are nonces, and the notation X {Y} indicates
that the message Y is transmitted, encrypted, and signed by X.
The text of X.509 states that checking timestamps tA and tB is optional for
three-way authentication. But consider the following example: Suppose A and B have
used the preceding protocol on some previous occasion, and that opponent C has
intercepted the preceding three messages. In addition, suppose that timestamps are
not used and are all set to 0. Finally, suppose C wishes to impersonate A to B. C
initially sends the first captured message to B:
C B: A {0, rA, IDB}
B responds, thinking it is talking to A but is actually talking to C:
B : C: B{0, roe B, IDA, rA}

 C meanwhile causes A to initiate authentication with C by some means. As a result,A
sends C the following:
C responds to A using the same nonce provided to C by B.
A responds with
This is exactly what C needs to convince B that it is talking to A, so C now repeats the
incoming message back out to B.
So B will believe it is talking to A, whereas it is actually talking to C. Suggest a simple
solution to this problem that does not involve the use of timestamps.  Get this solution


4.6 Consider a one-way authentication technique based on asymmetric encryption:
A B: IDA
B A: R1
A B: E(PRa, R1)
a. Explain the protocol.
b. What type of attack is this protocol susceptible to?  Get this solution


4.7 Consider a one-way authentication technique based on asymmetric encryption:
A B: IDA
B A: E(PUa, R2)
A B: R2
a. Explain the protocol.
b. What type of attack is this protocol susceptible to?  Get this solution


4.8 In Kerberos, when Bob receives a ticket from Alice, how does he know it is genuine? Get this solution


4.9 In Kerberos, when Bob receives a ticket from Alice, how does he know it came from
Alice? Get this solution


4.10 In Kerberos, Alice receives a reply, how does she know it came from Bob (that it’s not
a replay of an earlier message from Bob)?  Get this solution


4.11 In Kerberos, what does the ticket contain that allows Alice and Bob to talk securely? Get this solution


4.12 The 1988 version of X.509 lists properties that RSA keys must satisfy to be secure,
given current knowledge about the difficulty of factoring large numbers. The discussion
concludes with a constraint on the public exponent and the modulus n:
It must be ensured that e log2(n) to prevent attack by taking the
eth root mod n to disclose the plaintext.
Although the constraint is correct, the reason given for requiring it is incorrect.What
is wrong with the reason given and what is the correct reason? Get this solution


4.13 Find at least one intermediate certification authority’s certificate and one trusted root
certification authority’s certificate on your computer (e.g. in the browser). Print
screenshots of both the general and details tab for each certificate. Get this solution


4.14 NIST defines the term cryptoperiod as the time span during which a specific key is
authorized for use or in which the keys for a given system or application may remain
in effect. One document on key management uses the following time diagram for a
shared secret key.

Explain the overlap by giving an example application in which the originator’s usage
period for the shared secret key begins before the recipient’s usage period and also
ends before the recipient’s usage period. Get this solution

4.15 Consider the following protocol, designed to let A and B decide on a fresh, shared
session key K'AB.We assume that they already share a long-term key KAB.
1. A B: A, NA
2. B A: E(KAB, [NA, K'AB])
3. A B: E(K'AB, NA)
a. We first try to understand the protocol designer’s reasoning:
• Why would A and B believe after the protocol ran that they share K'AB with
the other party?
• Why would they believe that this shared key is fresh?
In both cases, you should explain both the reasons of both A and B, so your answer
should complete the following sentences.
A believes that she shares K'AB with B since . . .
B believes that he shares K'AB with A since . . .
A believes that K'AB is fresh since . . .
B believes that K'AB is fresh since . . .
b. Assume now that A starts a run of this protocol with B. However, the connection
is intercepted by the adversary C. Show how C can start a new run of the protocol
using reflection, causing A to believe that she has agreed on a fresh key with B (in
spite of the fact that she has only been communicating with C).Thus, in particular,
the belief in (a) is false.
c. Propose a modification of the protocol that prevents this attack.  Get this solution


4.16 What are the core components of a PKI? Briefly describe each component. Get this solution


4.17 Explain the problems with key management and how it affects symmetric cryptography. Get this solution


4.18 Consider the following protocol:
A KDC: IDA 7IDB 7N1
KDC A: E(Ka, [KS 7IDB 7N1 7E(Kb, [KS 7IDA]))
A B: E(Kb, [KS 7IDA])
B A: E(KS, N2)
A B: E(KS, f(N2))
a. Explain the protocol.
b. Can you think of a possible attack on this protocol? Explain how it can be done.
c. Mention a possible technique to get around the attack—not a detailed mechanism,
just the basics of the idea.
Note: The remaining problems deal with a cryptographic product developed by IBM,
which is briefly described in a document at this book’s Web site in IBMCrypto.pdf.
Try these problems after reviewing the document. Get this solution

4.19 What is the effect of adding the instruction EMKi?
EMKi: X E(KMHi, X) i 0, 1 Get this solution


4.20 Suppose N different systems use the IBM Cryptographic Subsystem with host master
keys KMH[i] (i 1, 2, . . . , N). Devise a method for communicating between systems
without requiring the system to either share a common host master key or to
divulge their individual host master keys. Hint: Each system needs three variants of its
host master key. Get this solution


4.21 The principal objective of the IBM Cryptographic Subsystem is to protect transmissions
between a terminal and the processing system. Devise a procedure, perhaps
adding instructions, which will allow the processor to generate a session key KS and
distribute it to Terminal i and Terminal j without having to store a key-equivalent
variable in the host.  Get this solution

Solutions - Network Security Essentials - Stallings - 4th ed - Chapter 3

3.1 Consider a 32-bit hash function defined as the concatenation of two 16-bit functions:
XOR and RXOR, which are defined in Section 3.2 as “two simple hash functions.”
a. Will this checksum detect all errors caused by an odd number of error bits?
Explain.
b. Will this checksum detect all errors caused by an even number of error bits? If
not, characterize the error patterns that will cause the checksum to fail.
c. Comment on the effectiveness of this function for use as a hash function for
authentication. Get this solution


3.2 Suppose H(m) is a collision-resistant hash function that maps a message of arbitrary
bit length into an n-bit hash value. Is it true that, for all messages x, x' with x x', we
have H(x) H(x')? Explain your answer. Get this solution


3.3 State the value of the padding field in SHA-512 if the length of the message is
a. 1919 bits
b. 1920 bits
c. 1921 bits  Get this solution

3.4 State the value of the length field in SHA-512 if the length of the message is
a. 1919 bits
b. 1920 bits
c. 1921 bits Get this solution

3.5 a. Consider the following hash function. Messages are in the form of a sequence of Get this solution

 

Then, add each column mod 26 and add the result to the running total, mod 26. In this

example, the running total is (24, 2, 6, 10). Round 2: Using the matrix from round 1,
rotate the first row left by 1, second row left by 2, third row left by 3, and reverse the
order of the fourth row. In our example:

Now, add each column mod 26 and add the result to the running total. The new running
total is (5, 7, 9, 11).This running total is now the input into the first round of the
compression function for the next block of text. After the final block is processed,
convert the final running total to letters. For example, if the message is ABCDE
FGHIJKLMNOP, then the hash is FHJL.
a. Draw figures comparable to Figures 3.4 and 3.5 to depict the overall tth logic and
the compression function logic.
b. Calculate the hash function for the 48-letter message “I leave twenty million dollars
to my friendly cousin Bill.”
c. To demonstrate the weakness of tth, find a 48-letter block that produces the same
hash as that just derived. Hint: Use lots of A’s.    Get this solution


3.7 It is possible to use a hash function to construct a block cipher with a structure similar
to DES. Because a hash function is one way and a block cipher must be reversible (to
decrypt), how is it possible? Get this solution


3.8 Now consider the opposite problem: Use an encryption algorithm to construct a oneway
hash function. Consider using RSA with a known key.Then process a message consisting
of a sequence of blocks as follows: Encrypt the first block, XOR the result with
the second block and encrypt again, and so on. Show that this scheme is not secure by
solving the following problem. Given a two-block message B1, B2, and its hash, we have
RSAH(B1, B2) RSA(RSA(B1) B2)
Given an arbitrary block C1, choose C2 so that RSAH(C1, C2) RSAH(B1, B2).
Thus, the hash function does not satisfy weak collision resistance.  Get this solution


3.9 One of the most widely used MACs, referred to as the Data Authentication Algorithm,
is based on DES. The algorithm is both a FIPS publication (FIPS PUB 113) and
an ANSI standard (X9.17). The algorithm can be defined as using the cipher block
chaining (CBC) mode of operation of DES with an initialization vector of zero
(Figure 2.10). The data (e.g., message, record, file, or program) to be authenticated is
grouped into contiguous 64-bit blocks: P1, P2, . . . , PN. If necessary, the final block is
padded on the right with 0s to form a full 64-bit block.The MAC consists of either the
entire ciphertext block CN or the leftmost Mbits of the block with 16 M 64. Show
that the same result can be produced using the cipher feedback mode.  Get this solution


3.10 In this problem, we will compare the security services that are provided by digital signatures
(DS) and message authentication codes (MAC).We assume that Oscar is able
to observe all messages send from Alice to Bob and vice versa. Oscar has no knowledge
of any keys but the public one in case of DS. State whether and how (i) DS and
(ii) MAC protect against each attack.The value auth(x) is computed with a DS or a
MAC algorithm, respectively.
a. (Message integrity) Alice sends a message x “Transfer $1000 to Mark”
in the clear and also sends auth(x) to Bob. Oscar intercepts the message and
replaces “Mark” with “Oscar”.Will Bob detect this?
b. (Replay) Alice sends a message x “Transfer $1000 to Oscar” in the
clear and also sends auth(x) to Bob. Oscar observes the message and signature
and sends them 100 times to Bob.Will Bob detect this?
c. (Sender Authentication with cheating third party) Oscar claims that he sent some
message x with a valid auth(x) to Bob, but Alice claims the same. Can Bob clear
the question in either case?
d. (Authentication with Bob cheating) Bob claims that he received a message x
with a valid signature auth(x) from Alice (e.g., “Transfer $1000 from Alice to
Bob”) but Alice claims she has never sent it. Can Alice clear this question in
either case?  Get this solution


3.11 Figure 3.14 shows an alternative means of implementing HMAC.
a. Describe the operation of this implementation.
b. What potential benefit does this implementation have over that shown in Figure 3.6?  Get this solution

 

Get this solution

Get solution for 3.13

Get solution for 3.14

3.15 In a public-key system using RSA, you intercept the ciphertext C 10 sent to a user
whose public key is e 5, n 35.What is the plaintext M? Get this solution


3.16 In an RSA system, the public key of a given user is e 31, n 3599.What is the private
key of this user?  Get this solution


3.17 Suppose we have a set of blocks encoded with the RSA algorithm and we don’t have the
private key.Assume n pq, e is the public key. Suppose also someone tells us they know
one of the plaintext blocks has a common factor with n. Does this help us in any way?  Get this solution

3.18 Show how RSA can be represented by matrices M1, M2, and M3 of Problem 3.4.  Get this solution

3.19 Consider the following scheme.
1. Pick an odd number, E.
2. Pick two prime numbers,P and Q, where (P 1)(Q 1) 1 is evenly divisible by E.
3. Multiply P and Q to get N.
4. Calculate .

Is this scheme equivalent to RSA? Show why or why not.  Get this solution


3.20 Suppose Bob uses the RSA cryptosystem with a very large modulus n for which the
factorization cannot be found in a reasonable amount of time. Suppose Alice sends a
message to Bob by representing each alphabetic character as an integer between
0 and 25 (A 0, . . ., Z 25), and then encrypting each number separately using
RSA with large e and large n. Is this method secure? If not, describe the most efficient
attack against this encryption method.  Get this solution


3.21 Consider a Diffie-Hellman scheme with a common prime q 11 and a primitive root
α 2.
a. If user A has public key YA 9, what is A’s private key XA?
b. If user B has public key YB = 3, what is the shared secret key K? Get this solution

Solutions - Network Security Essentials - Stallings - 4th ed - Chapter 2

Problems
2.1 This problem uses a real-world example of a symmetric cipher, from an old U.S.
Special Forces manual (public domain).The document, filename SpecialForces.pdf, is
available at this book’s Web site.  

a. Using the two keys (memory words) cryptographic and network security, encrypt
the following message:
Be at the third pillar from the left outside the lyceum theatre tonight at
seven. If you are distrustful bring two friends.
Make reasonable assumptions about how to treat redundant letters and
excess letters in the memory words and how to treat spaces and punctuation.
Indicate what your assumptions are. Note: The message is from the Sherlock
Holmes novel, The Sign of Four.
b. Decrypt the ciphertext. Show your work.
c. Comment on when it would be appropriate to use this technique and what its
advantages are.  Get this solution

2.2 Consider a very simple symmetric block encryption algorithm in which 32-bits blocks
of plaintext are encrypted using a 64-bit key. Encryption is defined as
C (P K0) K1
where C ciphertext, K secret key, K0 leftmost 64 bits of K, K1 rightmost
64 bits of K, bitwise exclusive OR, and is addition mod 264.
a. Show the decryption equation.That is, show the equation for P as a function of C,
K0, and K1.
b. Suppose and adversary has access to two sets of plaintexts and their corresponding
ciphertexts and wishes to determine K.We have the two equations:
C (P K0) K1; C' (P' K0) K1
First, derive an equation in one unknown (e.g., K0). Is it possible to proceed further
to solve for K0?   Get this solution

2.3 Perhaps the simplest “serious” symmetric block encryption algorithm is the Tiny
Encryption Algorithm (TEA). TEA operates on 64-bit blocks of plaintext using a
128-bit key. The plaintext is divided into two 32-bit blocks (L0, R0), and the key is
divided into four 32-bit blocks (K0,K1,K2,K3). Encryption involves repeated application
of a pair of rounds, defined as follows for rounds i and i 1:
Li Ri 1
Ri Li 1 F(Ri 1, K0, K1, δ
i)
Li 1 Ri
Ri 1 Li F(Ri, K2, K3, δ
i 1)
where F is defined as
F(M, Kj, Kk, δ
i) ((M 4) Kj) ((M 5) Kk) (M δi)
and where the logical shift of x by y bits is denoted by x y, the logical right shift of
x by y bits is denoted by x y, and δ
i is a sequence of predetermined constants.
a. Comment on the significance and benefit of using the sequence of constants.
b. Illustrate the operation of TEA using a block diagram or flow chart type of
depiction.
c. If only one pair of rounds is used, then the ciphertext consists of the 64-bit
block (L2, R2). For this case, express the decryption algorithm in terms of
equations.
d. Repeat part (c) using an illustration similar to that used for part (b).   Get this solution

2.4 Show that Feistel decryption is the inverse of Feistel encryption.  Get this solution

2.5 Consider a Feistel cipher composed of 16 rounds with block length 128 bits and key
length 128 bits. Suppose that, for a given k, the key scheduling algorithm determines
values for the first eight round keys, k1, k2, . . ., k8, and then sets
k9 = k8, k10 = k7, k11 = k6, . . ., k16 = k1  


Suppose you have a ciphertext c. Explain how, with access to an encryption oracle,
you can decrypt c and determine m using just a single oracle query.This shows that
such a cipher is vulnerable to a chosen plaintext attack. (An encryption oracle can
be thought of as a device that, when given a plaintext, returns the corresponding
ciphertext.The internal details of the device are not known to you, and you cannot
break open the device. You can only gain information from the oracle by making
queries to it and observing its responses.)   Get this solution

2.6 For any block cipher, the fact that it is a nonlinear function is crucial to its security.
To see this, suppose that we have a linear block cipher EL that encrypts 128-bit
blocks of plaintext into 128-bit blocks of ciphertext. Let EL(k, m) denote the
encryption of a 128-bit message m under a key k (the actual bit length of k is irrelevant).
Thus,
EL(k, [m1 m2]) EL(k,m1) EL(k,m2) for all 128-bit patterns m1,m2
Describe how, with 128 chosen ciphertexts, an adversary can decrypt any ciphertext
without knowledge of the secret key k. (A “chosen ciphertext” means that an adversary
has the ability to choose a ciphertext and then obtain its decryption. Here, you
have 128 plaintext–ciphertext pairs to work with, and you have the ability to chose
the value of the ciphertexts.)  Get this solution

2.7 Suppose you have a true random bit generator where each bit in the generated
stream has the same probability of being a 0 or 1 as any other bit in the stream and
that the bits are not correlated; that is, the bits are generated from identical independent
distribution. However, the bit stream is biased. The probability of a 1 is 0.5 δ
and the probability of a 0 is 0.5 δ, where 0 δ 0.5.A simple deskewing algorithm
is as follows: Examine the bit stream as a sequence of non-overlapping pairs. Discard
all 00 and 11 pairs. Replace each 01 pair with 0 and each 10 pair with 1.
a. What is the probability of occurrence of each pair in the original sequence?
b. What is the probability of occurrence of 0 and 1 in the modified sequence?
c. What is the expected number of input bits to produce x output bits?
d. Suppose that the algorithm uses overlapping successive bit pairs instead of
nonoverlapping successive bit pairs. That is, the first output bit is based on input
bits 1 and 2, the second output bit is based on input bits 2 and 3, and so on.What
can you say about the output bit stream? Get this solution

2.8 Another approach to deskewing is to consider the bit stream as a sequence of
non-overlapping groups of n bits each and output the parity of each group.That is,
if a group contains an odd number of ones, the output is 1; otherwise the output
is 0.
a. Express this operation in terms of a basic Boolean function.
b. Assume, as in the Problem 2.7, that the probability of a 1 is 0.5 δ. If each group
consists of 2 bits, what is the probability of an output of 1?
c. If each group consists of 4 bits, what is the probability of an output of 1?
d. Generalize the result to find the probability of an output of 1 for input groups of
n bits.  Get this solution

2.9 What RC4 key value will leave S unchanged during initialization? That is, after the
initial permutation of S, the entries of S will be equal to the values from 0 through 255
in ascending order.  Get this solution

2.10 RC4 has a secret internal state which is a permutation of all the possible values of the
vector S and the two indices i and j.
a. Using a straightforward scheme to store the internal state, how many bits are
used?
b. Suppose we think of it from the point of view of how much information is represented
by the state. In that case, we need to determine how may different states there are, then take the log to the base 2 to find out how many bits of information this represents. Using this approach, how many bits would be needed to represent the state?  Get this solution

2.11 Alice and Bob agree to communicate privately via e-mail using a scheme based on
RC4, but they want to avoid using a new secret key for each transmission. Alice and
Bob privately agree on a 128-bit key k.To encrypt a message m consisting of a string
of bits, the following procedure is used.
1. Choose a random 80-bit value v
2. Generate the ciphertext c RC4(v 7 k) m
3. Send the bit string (v 7 c)
a. Suppose Alice uses this procedure to send a message m to Bob. Describe how Bob
can recover the message m from (v 7 c) using k.
b. If an adversary observes several values (v1 7 c1), (v2 7 c2), . . . transmitted between
Alice and Bob, how can he/she determine when the same key stream has been
used to encrypt two messages? Get this solution

2.12 With the ECB mode, if there is an error in a block of the transmitted ciphertext, only
the corresponding plaintext block is affected. However, in the CBC mode, this error
propagates. For example, an error in the transmitted C1 (Figure 2.10) obviously corrupts
P1 and P2.
a. Are any blocks beyond P2 affected?
b. Suppose that there is a bit error in the source version of P1. Through how
many ciphertext blocks is this error propagated? What is the effect at the
receiver?  Get this solution

2.13 Is it possible to perform encryption operations in parallel on multiple blocks of plaintext
in CBC mode? How about decryption?  Get this solution

2.14 Suppose an error occurs in a block of ciphertext on transmission using CBC.What
effect is produced on the recovered plaintext blocks?  Get this solution

2.15 CBC-Pad is a block cipher mode of operation used in the RC5 block cipher, but it
could be used in any block cipher. CBC-Pad handles plaintext of any length. The
ciphertext is longer than the plaintext by at most the size of a single block.
Padding is used to assure that the plaintext input is a multiple of the block length.
It is assumed that the original plaintext is an integer number of bytes. This plaintext
is padded at the end by from 1 to bb bytes, where bb equals the block size in
bytes. The pad bytes are all the same and set to a byte that represents the number
of bytes of padding. For example, if there are 8 bytes of padding, each byte has the
bit pattern 00001000.Why not allow zero bytes of padding? That is, if the original
plaintext is an integer multiple of the block size, why not refrain from
padding?  Get this solution

2.16 Padding may not always be appropriate. For example, one might wish to store the
encrypted data in the same memory buffer that originally contained the plaintext. In
that case, the ciphertext must be the same length as the original plaintext. A mode for
that purpose is the ciphertext stealing (CTS) mode. Figure 2.13a shows an implementation
of this mode.
a. Explain how it works.
b. Describe how to decrypt Cn 1 and Cn.  Get this solution

2.17 Figure 2.13b shows an alternative to CTS for producing ciphertext of equal length to
the plaintext when the plaintext is not an integer multiple of the block size.
a. Explain the algorithm.
b. Explain why CTS is preferable to this approach illustrated in Figure 2.13b. Get this solution

2.18 If a bit error occurs in the transmission of a ciphertext character in 8-bit CFB mode,
how far does the error propagate?

 

Get this solution

Solutions - Network Security Essentials - Stallings - 4th ed - Chapter 1

Problems
1.1 Consider an automated teller machine (ATM) in which users provide a personal
identification number (PIN) and a card for account access. Give examples of confidentiality,
integrity, and availability requirements associated with the system. In each
case, indicate the degree of importance of the requirement. Get this solution

1.2 Repeat Problem 1.1 for a telephone switching system that routes calls through a
switching network based on the telephone number requested by the caller. Get this solution

1.3 Consider a desktop publishing system used to produce documents for various
organizations.
a. Give an example of a type of publication for which confidentiality of the stored
data is the most important requirement.
b. Give an example of a type of publication in which data integrity is the most
important requirement.
c. Give an example in which system availability is the most important requirement. Get this solution

1.4 For each of the following assets, assign a low, moderate, or high impact level for the
loss of confidentiality, availability, and integrity, respectively. Justify your answers.
a. An organization managing public information on its Web server.
b. A law-enforcement organization managing extremely sensitive investigative
information.
c. A financial organization managing routine administrative information (not
privacy-related information).
d. An information system used for large acquisitions in a contracting organization that
contains both sensitive, pre-solicitation phase contract information and routine
administrative information. Assess the impact for the two data sets separately and
the information system as a whole.
e. A power plant contains a SCADA (supervisory control and data acquisition) system
controlling the distribution of electric power for a large military installation.
The SCADA system contains both real-time sensor data and routine administrative
information. Assess the impact for the two data sets separately and the information
system as a whole. Get this solution

1.5 Draw a matrix similar to Table 1.4 that shows the relationship between security
services and attacks. Get this solution

1.6 Draw a matrix similar to Table 1.4 that shows the relationship between security
mechanisms and attacks. Get this solution