Isaca Updated CISA Exam Questions and Answers by miriam

 A digital signature is a cryptographic technique that verifies the authenticity and integrity of a message or document, by using a hash function and an asymmetric encryption algorithm. A hash function is a mathematical function that transforms any input data into a fixed-length output value called a digest, which is unique for each input. An asymmetric encryption algorithm uses two keys: a public key and a private key. The public key can be shared with anyone, while the private key must be kept secret by the owner. To create a digital signature, the sender first applies a hash function to the plaintext message togenerate a digest. Then, the sender encrypts the digest with their private key to produce the digital signature. To verify the digital signature, the receiver decrypts the digital signature with the sender’s public key to obtain the digest. Then, the receiver applies the same hash function to the plaintext message to generate another digest. If the two digests match, it means that the message has not been altered and that it came from the sender. The security of a digital signature depends on the secrecy of the sender’s private key. If an attacker obtains the sender’s private key, they can create fake digital signatures for any message they want, thus compromising the control provided by the digital signature. Reversing the hash function using the digest is not possible, as hash functions are designed to be one-way functions that cannot be inverted. Altering the plaintext message will result in a different digest after applying the hash function, which will not match with the decrypted digest from the digital signature, thus invalidating the digital signature. Deciphering the receiver’s public key is not relevant, as public keys are meant to be publicly available and do not affect the security of digital signatures. 

The audit charter is a document that defines the purpose, scope, authority, and responsibility of an IT audit organization. The audit charter should specify roles and responsibilities within an IT audit organization, such as who is accountable for approving the audit plan, who is responsible for conducting the audits, who is authorized to access the audit evidence, and who is accountable for reporting the audit results. The organizational chart, the engagement letter, and the annual audit plan are also important documents for an IT audit organization, but they do not specify roles and responsibilities as clearly and comprehensively as the audit charter. 

 A nondisclosure agreement (NDA) is the best way to protect an organization’s proprietary code during a joint-development activity involving a third party. An NDA is a legal contract that binds the parties involved in a joint-development activity to keep confidential any information, data or materials that are shared or exchanged during the activity. An NDA specifies what constitutes confidential information, how it can be used, disclosed or protected, how long it remains confidential, what are the exceptions and remedies for breach of confidentiality, and other terms and conditions. An NDA can help to protect an organization’s proprietary code from being copied, modified, distributed or exploited by unauthorized parties without its consent or knowledge. The other options are not as effective as option B, as they do not address confidentiality issues specifically. A statement of work (SOW) is a document that defines the scope, objectives, deliverables, tasks, roles, responsibilities, timelines and costs of a joint-development activity, but it does not cover confidentiality issues explicitly. A service level agreement (SLA) is a document that defines the quality, performance and availability standards and metrics for a service provided by one party to another party in a joint-development activity, but it does not cover confidentiality issues explicitly. A privacy agreement is a document that defines howpersonal information collected from customers or users is collected, used, disclosed and protected by one party or both parties in a joint-development activity, but it does not cover confidentiality issues related to proprietary code. References: CISA Review Manual (Digital Version) , Chapter 3: Information Systems Acquisition, Development & Implementation, Section 3.2: Project Management Practices.

IT disaster recovery time objectives (RTOs) are the maximum acceptable time that an IT system can be unavailable after a disaster before it causes unacceptable consequences for the business. IT RTOs should be based on the business-defined criticality of the systems, which reflects how important they are for supporting the business processes and functions. The maximum tolerable loss of data, the nature of the outage, and the maximum tolerable downtime (MTD) are also factors that affect the IT RTOs, but they are not the primary basis for determining them.