ISC Updated CISSP Exam Questions and Answers by rian

The security service that is served by the process of encrypting plaintext with the sender’s private key and decrypting ciphertext with the sender’s public key is identification. Identification is the process of verifying the identity of a person or entity that claims to be who or what it is. Identification can be achieved by using public key cryptography and digital signatures, which are based on the process of encrypting plaintext with the sender’s private key and decrypting ciphertext with the sender’s public key. This process works as follows:

• The sender has a pair of public and private keys, and the public key is shared with the receiver in advance.
• The sender encrypts the plaintext message with its private key, which produces a ciphertext that is also a digital signature of the message.
• The sender sends the ciphertext to the receiver, along with the plaintext message or a hash of the message.
• The receiver decrypts the ciphertext with the sender’s public key, which produces the same plaintext message or hash of the message.
• The receiver compares the decrypted message or hash with the original message or hash, and verifies the identity of the sender if they match.

The process of encrypting plaintext with the sender’s private key and decrypting ciphertext with the sender’s public key serves identification because it ensures that only the sender can produce a valid ciphertext that can be decrypted by the receiver, and that the receiver can verify the sender’s identity by using the sender’s public key. This process also provides non-repudiation, which means that the sender cannot deny sending the message or the receiver cannot deny receiving the message, as the ciphertext serves as a proof of origin and delivery.

The other options are not the security services that are served by the process of encrypting plaintext with the sender’s private key and decrypting ciphertext with the sender’s public key. Confidentiality is the process of ensuring that the message is only readable by the intended parties, and it is achieved by encrypting plaintext with the receiver’s public key and decrypting ciphertext with the receiver’s private key. Integrity is the process of ensuring that the message is not modified or corrupted during transmission, and it is achieved by using hash functions and message authentication codes. Availability is the process of ensuring that the message is accessible and usable by the authorized parties, and it is achieved by using redundancy, backup, and recovery mechanisms.

The component of the Security Content Automation Protocol (SCAP) specification that contains the data required to estimate the severity of vulnerabilities identified by automated vulnerability assessments is the Common Vulnerability Scoring System (CVSS). CVSS is a framework that provides a standardized and objective way to measure and communicate the characteristics and impacts of vulnerabilities. CVSS consists of three metric groups: base, temporal, and environmental. The base metric group captures the intrinsic and fundamental properties of a vulnerability that are constant over time and across user environments. The temporal metric group captures the characteristics of a vulnerability that change over time, such as the availability and effectiveness of exploits, patches, and workarounds. The environmental metric group captures the characteristics of a vulnerability that are relevant and unique to a user’s environment, such as the configuration and importance of the affected system. Each metric group has a set of metrics that are assigned values based on the vulnerability’s attributes. The values are then combined using a formula to produce a numerical score that ranges from 0 to 10, where 0 means no impact and 10 means critical impact. The score can also be translated into a qualitative rating that ranges from none to low, medium, high, and critical. CVSS provides a consistent and comprehensive way to estimate the severity of vulnerabilities and prioritize their remediation.

The other options are not components of the SCAP specification that contain the data required to estimate the severity of vulnerabilities identified by automated vulnerability assessments, but rather components that serve other purposes. Common Vulnerabilities and Exposures (CVE) is a component that provides a standardized and unique identifier and description for each publicly known vulnerability. CVE facilitates the sharing and comparison of vulnerability information across different sources and tools. Asset Reporting Format (ARF) is a component that provides a standardized and extensible format for expressing the information about the assets and their characteristics, such as configuration, vulnerabilities, and compliance. ARF enables the aggregation and correlation of asset information from different sources and tools. Open Vulnerability and Assessment Language (OVAL) is a component that provides a standardized and expressive language for defining and testing the state of a system for the presence of vulnerabilities, configuration issues, patches, and other aspects. OVAL enables the automation and interoperability of vulnerability assessment and management.

The person in the organization who is accountable for the classification of data information assets is the data owner. The data owner is the person or entity that has the authority and responsibility for the creation, collection, processing, and disposal of a set of data. The data owner is also responsible for defining the purpose, value, and classification of the data, as well as the security requirements and controls for the data. The data owner should be able to determine the impact of the data on the mission of the organization, which means assessing the potential consequences of losing, compromising, or disclosing the data. The impact of the data on the mission of the organization is one of the main criteria for data classification, which helps to establish the appropriate level of protection and handling for the data. The data owner should also ensure that the data is properly labeled, stored, accessed, shared, and destroyed according to the data classification policy and procedures.

The other options are not the persons in the organization who are accountable for the classification of data information assets, but rather persons who have other roles or functions related to data management. The data architect is the person or entity that designs and models the structure, format, and relationships of the data, as well as the data standards, specifications, and lifecycle. The data architect supports the data owner by providing technical guidance and expertise on the data architecture and quality. The Chief Information Security Officer (CISO) is the person or entity that oversees the security strategy, policies, and programs of the organization, as well as the security performance and incidents. The CISO supports the data owner by providing security leadership and governance, as well as ensuring the compliance and alignment of the data security with the organizational objectives and regulations. The Chief Information Officer (CIO) is the person or entity that manages the information technology (IT) resources and services of the organization, as well as the IT strategy and innovation. The CIO supports the data owner by providing IT management and direction, as well as ensuring the availability, reliability, and scalability of the IT infrastructure and applications.

Compressing the data before encryption is a technique that can be used to make an encryption scheme more resistant to a known plaintext attack. A known plaintext attack is a type of cryptanalysis where the attacker has access to some pairs of plaintext and ciphertext encrypted with the same key, and tries to recover the key or decrypt other ciphertexts. A known plaintext attack can exploit the statistical properties or patterns of the plaintext or the ciphertext to reduce the search space or guess the key. Compressing the data before encryption can reduce the redundancy and increase the entropy of the plaintext, making it harder for the attacker to find any correlations or similarities between the plaintext and the ciphertext. Compressing the data before encryption can also reduce the size of the plaintext, making it more difficult for the attacker to obtain enough plaintext-ciphertext pairs for a successful attack.

The other options are not techniques that can be used to make an encryption scheme more resistant to a known plaintext attack, but rather techniques that can introduce other security issues or inefficiencies. Hashing the data before encryption is not a useful technique, as hashing is a one-way function that cannot be reversed, and the encrypted hash cannot be decrypted to recover the original data. Hashing the data after encryption is also not a useful technique, as hashing does not add any security to the encryption, and the hash can be easily computed by anyone who has access to the ciphertext. Compressing the data after encryption is not a recommended technique, as compression algorithms usually work better on uncompressed data, and compressing the ciphertext can introduce errors or vulnerabilities that can compromise the encryption.