105. Which of the following key combinations is highly recommended to use in the triple data encryption algorithm (TDEA)?
a. Independent key 1, Independent key 2, Independent key 3
b. Independent key 1, Independent key 2, Independent key 1
c. Independent key 1, Independent key 2, Independent key 2
d. Independent key 2, Independent key 3, Independent key 3
105. a. Triple data encryption algorithm (TDEA) encrypts data in blocks of 64 bits, using three keys that define a key bundle. The use of three distinctly different (i.e., mathematically independent) keys is highly recommended because this provides the most security from TDEA; this is commonly known as three-key TDEA (3TDEA or 3TDES). The use of two-key TDEA (2TDEA or 2TDES), in which the first and third keys are identical and the second key is distinctly different, is highly discouraged. Other configurations of keys in the key bundle shall not be used.
106. For a cryptographic module, which of the following presents the correct relationships for sensitive security parameters?
a. Port security parameters plus private security parameters
b. Critical security parameters plus public security parameters
c. Data security parameters plus critical security parameters
d. Public security parameters plus program security parameters
106. b. Critical security parameters (CSP) contain security-related information (for example, secret and private cryptographic keys, and authentication data such as passwords and PINs) whose disclosure or modification can compromise the security of a cryptographic module or the security of the information protected by the module. Public security parameters (PSP) deal with security-related public information (for example, public keys) whose modification can compromise the security of a cryptographic module. Sensitive security parameters (SSP) contain both CSP and PSP. In other words, SSP = CSP + PSP. A trusted channel is generally established to transport the SSPs, data, and other critical information shared by the cryptographic module and the module’s operator.
The other three choices are incorrect. A port is a physical entry or exit point of a cryptographic module that provides access to the module for physical signals represented by logical information flows. The port security parameters along with data/program security parameters are not that important to the cryptographic module. The private security parameters do not exist.
107. The U.S. government imposes export controls on strong cryptography. Which of the following is the acceptable encryption key for use behind the firewall for use in foreign countries or in networks that include nodes in a foreign country?
a. 40 bits
b. 56 bits
c. 75 bits
d. 90 bits
107. a. Encryption using keys of 40 or fewer bits is only acceptable for use behind the firewall. Leading cryptographers recommend businesses use key lengths of at least 75 bits, with 90 bits being preferable. The Data Encryption Standard (DES) uses 56 keys, which is still acceptable for near term use.
108. Which of the following should be considered during configuration of cryptographic controls in the implementation phase of a system development life cycle (SDLC) as it applies to selecting cryptographic mechanisms?
1. Mathematical soundness of the algorithm
2. Length of the cryptographic keys
3. Key management
4. Mode of operation
a. 2 only
b. 3 only
c. 1, 2, and 3
d. 1, 2, 3, and 4
108. d. In the implementation phase, the focus is on configuring the system for use in the operational environment. This includes configuring the cryptographic controls. After the system has been configured, certification testing is performed to ensure that the system functions as specified and that the security controls are operating effectively. The security provided by a cryptographic control depends on the mathematical soundness of the algorithm, the length of the cryptographic keys, key management, and mode of operation. A weakness in any one of these components may result in a weakness or compromise to the security of the cryptographic control. A weakness may be introduced at any phase of the system life cycle.
109. Audit trails should be considered as part of which of the following security controls during the security design, implementation, and use of a cryptographic module?
a. Physical access controls
b. Logical access controls
c. Integrity controls
d. User authentication
109. c. Cryptography may provide methods that protect security-relevant software, including audit trails, from undetected modification. This is addressed as part of the integrity controls. Physical access controls are incorrect because they deal with prevention, detection, physical replacement or modification of the cryptographic system, and the keys within the system. Logical access controls are incorrect because they may provide a means of isolating the cryptographic software from attacks and modifications. The cryptographic module boundary may consist of the hardware, operating system, and cryptographic software. User authentication is incorrect because it includes use of cryptographic authentication to provide stronger authentication of users.
110. Which of the following is not a rule that guides the cryptography implementation in a system development life cycle (SDLC) as it applies to selecting cryptographic mechanisms?
a. Determine what information must be provided using a cryptographic function.
b. Change the cryptographic keys when employees leave the organization.
c. Protect data prior to signature generation/verification or encryption/decryption.
d. Provide the capability for local users to view all data that is being signed or encrypted.
110. b. It is a rule to follow in the operation and maintenance phase, not in the implementation phase. For example, cryptographic keys that are never changed, even when disgruntled employees leave the organization, are not secure. The other three choices are incorrect because they are the rules that guide the implementation of cryptography.
111. During the operation and maintenance phase of a system development life cycle (SDLC) as it relates to cryptography, which of the following requires configuration management most?
1. Hardware and firmware
2. System software maintenance and update
3. Application software maintenance
4. Cryptographic key maintenance
a. 1 and 2
b. 2 and 3
c. 3 and 4
d. 1, 2, 3, and 4
111. a. Configuration management (CM) is needed most for high-risk areas such as hardware and firmware and system software maintenance and update. CM ensures the integrity of managing system and security features through controlling changes made to a system’s hardware, firmware, software, and documentation. The documentation may include user guidance, test scripts, test data, and test results. The hardware and firmware maintenance scope covers adding new capabilities, expanding the system to accommodate more users, replacing nonfunctional equipment, changing platforms, and upgrading hardware components. The system software maintenance and update scope includes adding new capabilities, fixing errors, improving performance, and replacing keys.