Abstract: Cloud computing is termed as an emerging technology in the recent days due to advanced applications. In cloud, the security issues are increasing, which modelled a new concept as cloud forensics. The cloud forensic is an intelligent adaption of digital forensic, which can defeat crimes. Meanwhile, the centralized compilation of evidence and its perpetuation reduces feasibility of digital verification. This paper devises a novel forensic method, namely Evidence Integrity Preservation method using cloud-assisted blockchain network. Here, the log files are accumulated and preserved in the blockchain using different peers. For preserving the system from illegitimate users, the Elliptical curve cryptography (ECC) method is incorporated. Here, the system consists of five different entities, namely Hypervisor (VMM), Node controller, log ledger, IPFS file storage, and Smart contract. The proposed method involves six different phases, such as Log File creation phase, Key Setup and exchange phase, Evidence setup and control phase, integrity assurance phase, Agreement validation and confidential file release and blockchain-based communication phase. This model incorporates Interplanetary File System (IPFS) for the effective data sharing between cloud owner and investigator. The proposed Evidence Integrity Preservation method provides superior performance in contrast to other methods with maximal detection rate of 0.9 and minimal memory of 1342176 bytes.

Cloud computing, Blockchain, Security, Privacy preservation, Cloud forensics