1.0 KiB
1.0 KiB
Key Distribution
A wants to talk to B but securely(duh). A trusted third party steps in to provide keys
Needham-Schoeder
used to authenticate users
Say we have A & B that want to talk.
A sends (IDA, IDB) to KDC
KDC sends Enc(SessionKeyA, IDB, Nonce1, Enc(SessionKeyB, SharedKeyA, IDA)) to A
A sends Enc(SessionKeyB, SharedKeyB, IDA) // this bit came in the package from last round
...
...
Denning
Fixes step 3 with timestamps. We also shorten the overall process. Problem: both parties need to be time synchronized.
NOTE: the Sessionkey below is shared between A and B. THe SharedKeyX is shared between the Key Distribution Center and the user.
- A sends {IDA, NonceA} B
- B sends {NonceB, Enc(SharedKeyB, [IDA, NonceA, TimeB])} to KDC
- KDC sends {Enc(SharedKeyA, [IDB,, NonceA, SessionKey, TimeB), E(SharedKeyB, [IDA, SessionKey, TimeB]), NonceB} to A
- A sends {E(SharedKey, [IDA, SessionKey, TimeB]), E(SessionKey, NonceB} to B
Kerberos
The model itself can be thought of similar to