How to provide authentication

Standard method: digital signatures
- Need a Certification Authority to certify the private-public keys
- Signing is expensive: 10 ms to sign using RSA 1024-bit, 0.5ms to verify using RSA
- ‘helps’ denial of service
Establishing a Certification Authority (CA) difficult in a mobile ad hoc network, since the authority may not be reachable from all nodes at all times

Standard method: digital signatures