<p>The widespread adoption of Internet of Things (IoT) technology improves conjunction and communication, impacting nearly every area of our daily existence, from manufacturing and retail to smart homes. However, the limited resources of these devices often result in lower levels of security protection, creating opportunities for malicious users. To address IoT security issues, a forensics system is needed to collect, process, analyze, authenticate, and report evidence of attacks. Although systems have been examined extensively within the previous years and solutions like cloud-based authentication for IoT forensics have been proposed, certain limitations, such as centralized storage, remain. In this article, we suggested a blockchain-based authentication framework for the forensics IoT system, utilizing blockchain technology to improve the integrity, authenticity, and non-repudiation of the collected evidence. The security and privacy of the framework are confirmed through the ROR model, Scyther tool, and informal security assessments. Additionally, a comparative analysis offers an in-depth review of its communication and computational costs, as well as its security attributes compared to existing protocols, highlighting its enhanced security and efficiency.</p>