A digital signature is a cryptographic technique that uses the sender's private key to generate a unique code for a message or document. The receiver can use the sender's public key to verify the authenticity and integrity of the message or document. A digital signature can prevent unauthorized change, as any modification to the message or document will invalidate the signature and alert the receiver of tampering.
References
What is a digital signature?
Digital Signature - an overview | ScienceDirect Topics
ISACA CISA Review Manual, 27th Edition, page 253

ipchains is a free software based firewall running on earlier Linux. It is a rewrite of ipfwadm but is superseded by iptables in Linux 2.4 and above. Iptables controls the packet filtering and NAT components within the Linux kernel. It is based on Netfilter , a framework which provides a set of hooks within the Linux kernel for intercepting and manipulating network packets.

Comprehensive and Detailed Step-by-Step Explanation:
To efficiently detectduplicate payments,data analyticsand automated checks are required due to thehigh volume of transactions.
* Option A (Correct):Computer-Assisted Audit Techniques (CAATs)allow auditors toautomatically scan large datasetsfor duplicate payments based oninvoice numbers, vendor names, and payment amounts.
* Option B (Incorrect):Stratified samplinggroups data into categories, which helps in analysis but does not directly detect duplicates.
* Option C (Incorrect):Statistical samplingis useful forextrapolating results, but it doesnot systematically findduplicate transactions.
* Option D (Incorrect):Process walk-throughsreview procedures but donot analyze transactions at scale.
Reference:ISACA CISA Review Manual -Domain 2: Governance and Management of IT- Covers CAATs, data analytics, and fraud detection techniques.

If a database is restored from information backed up before the last system image,
the system should be restarted before the last transaction because the final transaction must be
reprocessed.