*3.6. Evidence Database*

The evidence database is a standard database and/or file repository that stores the actual digital evidence together with an identification ID computed from the evidence's hash and a nonce. This database is disseminated and is maintained by a number of reputable organizations (e.g., law, court, officers). Additionally, each access is granted only if the asking organization is allowed to provide it in accordance with its function. There are two reasons for this split (between the Evidence Log and the Evidences database). To begin, evidence may be too big to be kept effectively on the blockchain (for example, a piece of evidence may be a bit-by-bit copy of a storage device of several TBs of capacity). Second, and most crucially, if pieces of evidence are kept on the blockchain, they are accessible to all nodes in the blockchain network, while only authorized nodes should be permitted to collect evidence. As a result, we keep just information on the CoC process and a hash of the evidence in the blockchain, which enables us to check the integrity of pieces of evidence throughout acquisition [21]. See [41–47] for more information about protecting digital evidence integrity and preserving chain of custody.

#### **4. Performance Evaluation and Analysis**

Performance is the most desired characteristic of any problem-solving endeavor, and this is also true for Blockchain-based solutions. We utilized Hyperledger Caliper to assess the performance of our prototype. Caliper enables users to benchmark the performance of various blockchain systems against a specified set of use cases and produce reports that include performance metrics such as transactions per second (tps) and transaction latency (the time elapsed from the issue of the transaction to its inclusion in the blockchain). The experiments were conducted on an Intel Core i7–5500U, 2.4 GHz processor, 8 GB DDR3 RAM laptop, and Windows 10 operating system. The code was written in Python language using Python 3.6 software.
