Maude-NPA

Repository of protocol specifications in Maude-NPA

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Needham Schroeder Lowe with XOR Protocol

This protocol uses the following algebraic properties: the exclusive-or (XOR) and the cancellation of encryption and decryption.

The protocol specification in "Alice-Bob" notation is as follows:

  1. A -> B : Kb:A , Na
  2. B -> A : Ka:Nb , B ⊕ Na
  3. A -> B : Kb:Nb

We use the symbol " ⊕ " to represent the XOR operator.

For this protocol we considered the following executions:

  1. A regular execution of the protocol (denoted by attack-state(0)).
  2. An execution in which the intruder finds out the Session key generated by the server (denoted by attack-state(1)).
  3. An execution in which Bob completed his protocol execution believing he was communicating with Alice, but it actually was not so (denoted attack-state (2)).

After the analysis of this protocol in Maude-NPA, the tool found an initial state corresponding to attack-state(0), which shows a completed regular execution of the protocol. However, the tool did not find any initial state for attack-state(1) and attack-state(2) which proves, respectively, that the protocol is secure against an attack to obtain the session key and against an authentication attack.

 

To download the complete protocol specification in Maude-NPA syntax and outputs, click HERE