## 6 Evaluation and Security
### Protection Against Specific Attacks  
The proposed protocol is designed to counter a variety of specific attack vectors commonly encountered in distributed environments. Each of these potential threats is addressed through tailored mechanisms that work in concert to secure communications and data.  
**Man-in-the-Middle (MitM) Attacks:**  
Man-in-the-Middle attacks involve an adversary intercepting communications between two parties with the aim of eavesdropping or altering the transmitted messages. In our protocol, robust cryptographic keys and advanced encryption mechanisms--specifically using the Ascon algorithm--serve as the first line of defense. By encrypting all communications end-to-end, the protocol ensures that any intercepted messages remain unreadable without the appropriate decryption key. Additionally, blockchain-based authentication guarantees that both parties are verified before any exchange occurs, making it exceedingly difficult for an attacker to successfully impersonate either party or inject fraudulent data into the communication stream.  
**Brute Force Attacks:**  
Brute force attacks attempt to decipher encrypted data by systematically testing every possible key until the correct one is found. The protocol mitigates this threat by relying on the inherent strength and high computational complexity of the Ascon algorithm. As Ascon is designed with a large key space and strong cryptographic primitives, it renders any brute force attempt computationally prohibitive, effectively ensuring that decryption without the correct key remains virtually impossible.  
**Phishing Attacks:**  
Phishing attacks typically target user credentials by tricking users into disclosing sensitive information. To counteract this threat, the protocol enforces strict authentication through smart contracts and the use of unique session tokens. This multi-factor approach ensures that even if an attacker manages to compromise a user's login details, the additional security layer provided by session tokens and the smart contract authentication checks will prevent unauthorized access to system resources.  
**Denial-of-Service (DoS) Attacks:**  
Denial-of-service attacks aim to overwhelm a system with excessive traffic, thereby rendering it unavailable to legitimate users. The decentralized architecture of our protocol, which leverages both blockchain and IPFS, inherently mitigates this risk. The distributed nature of the system eliminates single points of failure, ensuring that even if certain nodes or segments of the network are targeted and become temporarily inoperative, the overall system remains operational. This redundancy and distribution of workload significantly reduce the impact of DoS attacks.  
**Data Corruption:**  
Ensuring data integrity is critical in any secure system. Our protocol defends against data corruption by combining the immutability of the blockchain with IPFS's content-based addressing. In this system, any unauthorized modification of data results in a discrepancy between the stored cryptographic hash and the actual content. Such a mismatch is immediately detectable, ensuring that any attempts to corrupt the data are promptly identified and can be addressed before further harm is carried out.  
**Eavesdropping:**  
Eavesdropping involves the unauthorized interception of data during transmission. To guard against this, all communications within the protocol are encrypted using the strong, lightweight encryption provided by Ascon. This ensures that even if an attacker is able to tap into the communication channel, the intercepted data will remain encrypted and indecipherable without the correct decryption key, thereby preserving the confidentiality of the transmitted information.