Explanation
The most effective way to ensure the integrity of data transmitted over a network is to use a message digest. A message digest is a cryptographic function that generates a unique and fixed-length value (also known as a hash or checksum) from any input data. The message digest can be used to verify that the data has not been altered or corrupted during transmission by comparing it with the message digest generated at the destination.
Message encryption is a method of protecting the confidentiality of data transmitted over a network by transforming it into an unreadable format using a secret key. Message encryption does not ensure the integrity of data, as it does not prevent or detect unauthorized modifications. Certificate authority (CA) is an entity that issues and manages digital certificates that bind public keys to identities. CA does not ensure the integrity of data, as it does not prevent or detect unauthorized modifications. Steganography is a technique of hiding data within other data, such as images or audio files. Steganography does not ensure the integrity of data, as it does not prevent or detect unauthorized modifications. References:
CISA Review Manual, 27th Edition, pages 383-3841
CISA Review Questions, Answers & Explanations Database, Question ID: 258

Explanation/Reference:
Explanation:
A directory server makes other users' certificates available to applications. Encrypting the information transmitted over the network and storing certificate revocation lists (CRLs) are roles performed by a security server. Facilitating the implementation of a password policy is not relevant to public key infrastructure (PKl).

Explanation/Reference:
Explanation:
The inability to specify purpose and usage patterns is a risk that developers need to anticipate while implementing a decision support system (DSS). Choices A, B and D are not risks, but characteristics of a DSS.