The Andrew Secure RPC Handshake protocol Software Security

Introduction:

Authentication is an access connection is an authentication the user to the Server. An authentication protocol is used here. Authentication protocols are the basis of security in many systems.

Top 4 authentication protocol:

The CCITT X.509 protocol.
The KERBEROS protocol.
The NEEDHAM-Schroeder public-Key protocol.
The Andrew Secure RPC Handshake protocol.

Basic Notation:

Special principals: A, B, S.
Special shared keys: K_ab, K_bs, K_as.
Special Public keys: K_a, K_b, K_s.
Secret Keys: K^-1_a, K^-1_b, K^-1_s^.
Specific Statement: N_a, N_b, N_c.
Range over principals: P, Q, R.
Range over Statements: X, Y.
Range over encryption keys: K.

P believes X: The principal P may act as though X is true.
P sees X: Someone has sent a message containing X to P, who can read and repeat X.
P said X: The principal P at some time sent a message including the statement X.

P controls X: P has jurisdiction over X.
P <-k-> Q: P and Q may use the shared key K to communicate.
K-> P: P has K as a public key.
{X}k: This represents the formula X encrypted under the key K.
{X}y: This represents X combined with the formula Y.

The Andrew Secure RPC Handshake protocol.

The Andrew secure RPC handshake uses an authentication handshake between two principals whenever a Client (X) binds to a new Server (Y).

The handshake is intended to allow a client X to obtain a session key K’xy from a server Y, given that they already share a key Kxy.

Message 1: X -> Y: X, {Nx} Kxy.

Message 2: Y -> X: {Nx + 1, Ny} Kxy.

Message 3: X -> Y: {Ny + 1} Kxy.

Message 4: Y -> X: {K’xy, N’y} Kxy.

The first message simply transfers a nonce, then Y returns in the second message.

If X is satisfied with the reply (from Y) he returns Y’s nonce, then Y receives and check the third message and he sends a new session key to X and nonces are returned increment by one.

Message 1: X -> Y: X, {Nx} Kxy.

Message 2: Y -> X: {Nx, Ny} Kxy.

Message 3: X -> Y: {Ny} Kxy.

Message 4: Y -> X: {X <-Kxy-> Y, N’y} Kxy.

The protocol Analysis:

Client:

X believes X <-K_xy-> Y
X believes (Y controls X <- k -> Y)
X believes fresh (N_x)

Server Side:

Y believes X <-K_xy-> Y
Y believes X <-K’_xy-> Y
Y believes fresh (N_y)
Y believes fresh (N’_y)

Any, the predictable message will assure Y that X has encrypted something with the new key.

	CCITT X.509	KERBEROS	NEEDHAM PUBLIC-KEY	ANDREW RPC
Goal	Transfer Data	Distribute key	Establish secrets	Distribute extra key
Keys	Public	Shared	Public	Shared
Proves	X and Y^y	X and Y^y	X and Y	X and Y