Ransomware uses strong encryption algorithms, like AES and RSA, to make files inaccessible. Once encrypted, the keys are held by the attacker. Without the key, decryption is virtually impossible. Modern ransomware has made brute force or guessing infeasible, even for experts. This is why ransomware is so effective.
It matters because traditional IT recovery methods fail. Prevention and backups are critical.
It also illustrates the dual-use nature of cryptography: secure communication and malicious extortion.
Modern ransomware relies on unbreakable encryption to lock files.
[Kaspersky, kaspersky.com]