Encryption, least privilege, zero trust

These are the handful of principles behind most secure system design. Encryption in transit (TLS) protects data moving across networks from eavesdropping and tampering, and encryption at rest protects stored data if disks or backups are stolen, with the real difficulty being how you manage and rotate the keys. Least privilege means every person, service and token gets only the permissions it needs, so a compromise of any one does limited damage. Zero trust drops the old idea that anything inside the company network is safe: every request is authenticated and authorised on its own merits, wherever it comes from. Together they assume breaches will happen and aim to contain them.