# CISSP Domain 3 Questions – History, Goals, Concepts of Cryptography

Question: When we talk about using cryptanalysis in our work, what are we doing?
The science of breaking encrypted communications.
This is Correct. Cryptanalysis is the science of breaking encrypted communication. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown. It uses mathematical analysis of the cryptographic algorithm, as well as side-channel attacks that do not target weaknesses in the cryptographic algorithms themselves, but instead exploit weaknesses in their implementation and the devices that run them
The science of securing communications.
This is Incorrect.
A cryptographic algorithm.
This is Incorrect.
Creates messages with a hidden meaning.
This is Incorrect.
Question: When we are replacing one character with another, what is that called?
Substitution
This is Correct.
Confusion
This is Incorrect.
Diffusion
This is Incorrect.
Permutation
This is Incorrect.
Question: The order of the plaintext should be dispersed in the ciphertext. What is this called?
Diffusion
This is Correct.
Confusion
This is Incorrect.
Permutation
This is Incorrect.
Substitution
This is Incorrect.
Question: What is the relationship between plaintext and ciphertext is called?
Confusion
This is Correct.
Permutation
This is Incorrect.
Substitution
This is Incorrect.
Diffusion
This is Incorrect.
Question: A historical type of encryption that was based on a set of disks with random letters; the sender and receiver would agree on the disk order. What is it called?
Bazeries
This is Correct. The Jefferson Disk (Bazeries Cylinder) – is a cipher system using a set of wheels or disks, each with the 26 letters of the alphabet arranged around the edge. Jefferson (US president) invented it, and Bazeries improved it. The order of the letters is different for each disk and is usually scrambled in some random way. Each disk is marked with a unique number. A hole in the center of the disks allows them to be stacked on an axle. The disks are removable and can be mounted on the axle in any order desired. The order of the disks is the cipher key, and both sender and receiver must arrange the disks in the same predefined order. Jefferson’s device had 36 disks.
Vigenére cipher
This is Incorrect.
Spartan Scytale
This is Incorrect.
Caesar cipher
This is Incorrect.
Question: After the Second World War the US designed and built the SIGABA. How many rotors did it use?
15
This is Correct. SIGABA: A rotor machine used by the United States throughout World War II and into the 1950s, similar to the Enigma. It was more complex, and was built after examining the weaknesses of the Enigma. No successful cryptanalysis of the machine during its service lifetime is publicly known. It used 3x 5 sets of rotors.
3
This is Incorrect.
4
This is Incorrect.
10
This is Incorrect.
Question: What historical encryption was written on a thin piece of parchment that was wrapped around a round stick of a certain diameter?
Spartan Scytale.
This is Correct. Spartan Scytale – Message written lengthwise on a long thin piece of parchment wrapped around a certain size round stick. By itself it would make no sense, but if rewrapped around a stick of the same diameter it would be decipherable.
Vigenére cipher.
This is Incorrect.
Bazeries.
This is Incorrect.
Caesar cipher.
This is Incorrect.
Question: The original version of the Enigma machines encryption was broken by the Polish intelligence in 1939. When it was broken in 1939, how many rotors did it use?
3
This is Correct. Enigma – Rotary based. Was three rotors early on, which were broken, so the Germans added one rotor, making it much harder. Breaking the Enigma was responsible for ending the war early and saving millions of lives.
4
This is Incorrect.
10
This is Incorrect.
5
This is Incorrect.
Question: Which of these rotary based encryption machines was NOT known to have been broken while it was in active use?
SIGABA
This is Correct. SIGABA: A rotor machine used by the United States throughout World War II and into the 1950s, similar to the Enigma. It was more complex, and was built after examining the weaknesses of the Enigma. No successful cryptanalysis of the machine during its service lifetime is publicly known. It used 3x 5 sets of rotors.
Enigma
This is Incorrect.
Purple
This is Incorrect.
PRAAS
This is Incorrect.
Question: The original Enigma machine was broken by the Polish in 1939. How many rotors did the Enigma use at the end of the Second World War?
4
This is Correct. Enigma – Rotary based. Was 3 rotors early on, which was broken, so the Germans added 1 rotor, making it much harder. Breaking the Enigma was responsible for ending the war early and saving millions of lives.
3
This is Incorrect.
10
This is Incorrect.
5
This is Incorrect.
Question: Which one of the following cryptographic goals protects against the risks posed when a device is lost or stolen?
Confidentiality
This is Correct. The greatest risk when a device is lost or stolen is that sensitive data contained on the device will fall into the wrong hands. Confidentiality protects against this risk.
Integrity
This is Incorrect.
Non-repudiation
This is Incorrect.
Authentication
This is Incorrect.
Question: What logical operation is described by the truth table shown here?
XOR
This is Correct. The exclusive or (XOR) operation is true when one and only one of the input values is true.
AND
This is Incorrect.
OR
This is Incorrect.
NOR
This is Incorrect.
Question: How many possible keys exist for a cipher that uses a key containing 5 bits?
32
This is Correct. Binary keyspaces contain a number of keys equal to two raised to the power of the number of bits. Two to the fifth power is 32, so a 5-bit keyspace contains 32 possible keys.
16
This is Incorrect.
10
This is Incorrect.
64
This is Incorrect.
Question: Alice sent a message to Bob. Bob would like to demonstrate to Charlie that the message he received definitely came from Alice. What goal of cryptography is Bob attempting to achieve?
Non-repudiation
This is Correct. Nonrepudiation occurs when the recipient of a message is able to demonstrate to a third party that the message came from the purported sender.
Confidentiality
This is Incorrect.
Availability
This is Incorrect.
Authentication
This is Incorrect.
Question: When we are rearranging the plaintext what is it called?
Permutation
This is Correct.
Confusion
This is Incorrect.
Diffusion
This is Incorrect.
Substitution
This is Incorrect.
Question: Which historical type of encryption involved the sender switching letters a certain number of spots forwards or back in the alphabet, with the receiver doing the same in the opposite direction?
Caesar Cipher
This is Correct.
Vigenere Cipher
This is Incorrect.
Spartan Scytale
This is Incorrect.
Bazeries
This is Incorrect.
Question: Which one of the following is an example of a code, not a cipher?
“One if by land; two if by sea”
This is Correct. The major difference between a code and a cipher is that ciphers alter messages at the character or bit level, not at the word level. DES, shift ciphers, and word scrambles all work at the character or bit level and are ciphers. “One if by land; two if by sea” is a message with hidden meaning in the words and is an example of a code.
Word scramble
This is Incorrect.
Data Encryption Standard
This is Incorrect.
Shifting letters by three
This is Incorrect.
Question: Which process converts plaintext into ciphertext?
Encryption
This is Correct. Encryption converts plaintext into ciphertext. Hashing reduces a message to a hash value. Decryption converts ciphertext into plaintext. A digital signature is an object that provides sender authentication and message integrity by including a digital signature with the original message.
Digital Signature
This is Incorrect.
Hashing
This is Incorrect.
Decryption
This is Incorrect.
Question: For security protection mechanisms for cryptographic data in storage, backup, and archives, the storage of keying material is a part of which of the following cryptographic services?
Availability
This is Correct. The availability service for data in storage deals with backup and archive storages. During a key’s crypto-period, keying material (i.e., keys and initialization vectors) should be stored in both normal operational storage and in backup storage. After the end of a key’s crypto-period, keying material should be placed in archive storage. The other three choices do not deal with backup and archive storages.
Integrity
This is Incorrect.
Confidentiality
This is Incorrect.
Labels
This is Incorrect.
Question: What is the output value of the mathematical function 16 mod 3?
1
This is Correct.
0
This is Incorrect.
3
This is Incorrect.
5
This is Incorrect.
Question: Which of the following is not addressed in the Wassenaar Arrangement?
Products exported to terrorist countries.
This is Correct. In 1996 several countries (33 in all) came together to control the exportation of the same type of items to the agreed upon “terrorist countries,” and their guidelines are referred to as the Wassenaar Arrangement. These countries (Iran, Iraq, Libya, North Korea, Sudan, Cuba, and Syria) were identified as having connections with terrorist groups and activities. The agreed upon controls did not apply to products that could be downloaded from the Internet.
This is Incorrect.
Asymmetric algorithms
This is Incorrect.
Symmetric algorithms
This is Incorrect.

## 3 thoughts on “CISSP Domain 3 Questions – History, Goals, Concepts of Cryptography”

1. Excellent questions!

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• Thank you Wentz Wu

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