How can you design systems to prevent man-in-the-middle attacks?

1 Use encryption

Encryption is the process of transforming data into a form that only the intended recipients can understand, using a secret key or algorithm. Encryption can prevent MITM attackers from reading or modifying the data in transit, as they would need to know the key or algorithm to decrypt it. Encryption can be applied at different layers of the communication protocol, such as the application layer (e.g., HTTPS, SSL, TLS), the transport layer (e.g., TCP, UDP), or the network layer (e.g., IPsec, VPN). You should use encryption whenever you transmit sensitive or confidential data over a network.

2 Use authentication

Authentication is the process of verifying the identity of a party or a message, using a credential or a signature. Authentication can prevent MITM attackers from impersonating or spoofing the legitimate parties, as they would need to possess or forge the credential or signature to authenticate themselves. Authentication can be based on different factors, such as something you know (e.g., password, PIN), something you have (e.g., token, certificate), or something you are (e.g., biometric, fingerprint). You should use authentication whenever you need to establish trust or authority between parties.

3 Use authorization

Authorization is the process of granting or denying access to a resource or an action, based on the identity or the role of a party. Authorization can prevent MITM attackers from accessing or performing unauthorized operations on the system, as they would need to have the appropriate permissions or privileges to do so. Authorization can be implemented using different models, such as discretionary access control (DAC), mandatory access control (MAC), or role-based access control (RBAC). You should use authorization whenever you need to enforce policies or rules on the system.

4 Use validation

Validation is the process of checking the correctness or the completeness of a message or a data input, using a schema or a format. Validation can prevent MITM attackers from injecting or corrupting the data with malicious or erroneous values, as they would need to comply with the schema or the format to pass the validation. Validation can be performed at different stages of the communication process, such as before sending, after receiving, or before processing. You should use validation whenever you need to ensure the quality or the integrity of the data.

5 Use monitoring

Monitoring is the process of observing and recording the activity or the performance of a system or a network, using logs or metrics. Monitoring can help you detect and respond to MITM attacks, as you can identify and analyze any anomalies or deviations from the normal or expected behavior. Monitoring can also help you improve and optimize your system or network, as you can measure and evaluate the efficiency or the effectiveness of your design. You should use monitoring whenever you need to maintain or enhance your system or network.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?