Several formal methods: BAN Logic String Space Model Certification Test Theory
The following is a summary based on the BAN logic method:
BAN logic
1. Basic terms
Principal: The parties involved in the authentication protocol.
Viewpoint (formula, statement): The meaning of the message in the authentication protocol.
A, B, C: Specific authentication subjects.
Kab, Kas, Kbs: The shared key of the specific authentication subject.
Ka, Kb, Kc: the secret key of the specific authentication subject.
Ka-1, Kb-1, Kc-1: the secret key of the specific authentication subject.
Na, Nb, Nc: specific point of view (statement).
P, Q, R: Subjects in the general sense, representing the concept of a range.
X, Y: A general point of view (statement).
K: Encryption key in the general sense, representing the concept of a range.
(X,Y): Connection of X and Y.
P|≡X: P believes X, or P has the right to believe X. In particular, subject P believes that X is true.
P|~X: P has said X, and subject P has sent a message containing X at some point.
P|⊿X: P has seen X, some subject has sent a message containing X, and P can read and repeat X.
P|=>X: P has arbitration right over X.
#(X): X is fresh.
2. Rules of inference
3. Protocol Analysis Steps
The steps of BAN logic analysis authentication protocol include:
1) Idealization of the protocol. The idealized protocol is derived from the original protocol, that is, the message in the protocol is converted into the corresponding logical language representation. Here, it refers to the process of converting the actual protocol into the logical language representation of BAN logic.
2) Determine the initial hypothesis. Find out the initial belief assumptions that complete the protocol, which are the conditions under which the messages in the protocol work. Initial assumptions include belief assumptions (trust relationship, etc.) and state assumptions (arbitration rights, etc.).
3) Identify assertions. A logical formula is appended to the protocol statement, ie an assertion is given for each protocol statement.
4) Logical reasoning process. Apply the rules of logical reasoning to assumptions and assertions to arrive at the ultimate belief of each certification subject.
5) Draw conclusions. Judge the final logical result to determine whether the purpose of the protocol design is achieved and whether there are loopholes in the protocol.
4. The purpose of certification
5. Example analysis (taking the Kerberos protocol as an example)
The BAN logic analysis process is as follows:
The whole process is obtained according to BAN logic rules and messages, the general process is like this~