Quiz Entry - updated: 2026.07.14
Which 4 of the 8 attacks can be solved directly with cryptographic mechanisms, and which 4 require additional application-level measures?
Eavesdropping, modifying, inserting, and non-repudiation of origin are solved by crypto directly; replay, delete, masquerade, and non-repudiation of receipt need application-level measures.
* Four attacks fall to crypto primitives; four more need sequence numbers or challenge-response on top. *
Solvable by cryptographic primitives:
| Attack | Solution |
|---|---|
| Eavesdropping | Encryption (symmetric or asymmetric) |
| Modifying | MAC or Digital Signature |
| Inserting | MAC or Digital Signature |
| Non-repudiation of origin | Digital Signature (asymmetric only!) |
Require additional application measures:
| Attack | Solution |
|---|---|
| Replay | Sequence numbers or timestamps |
| Delete | Sequence numbers (detect gaps) |
| Masquerade | Challenge-Response protocols (authentication) |
| Non-repudiation of receipt | Application-level protocols (e.g., delivery receipts) |
Key insight: The 4 basic crypto principles (symmetric/asymmetric encryption, MAC, digital signature) handle the first group elegantly. But the second group needs additional protocol design on top of the crypto primitives.