Complex programming problem!

[GreyGeek]

"Whenever you have a complex programming problem, break it into a client and a server. Now you have two complex programming problems, a protocol design problem, and a security vulnerability."

--
Russ Allbery

[SteveRiley]

a security vulnerability

And opportunities for any or all of the following actors to dutifully perform their assigned roles...

Alice and Bob. Generally, Alice wants to send a message to Bob. These names were used by Ron Rivest in the 1978 Communications of the ACM article presenting the RSA cryptosystem, and in A Method for Obtaining Digital Signatures and Public-Key Cryptosystems published 4 April 1977, revised 1 September 1977 as Technical Memo LCS/TM82. Rivest denies that these names have any relation to the 1969 movie Bob & Carol & Ted & Alice as occasionally suggested by others.

Carol, Carlos or Charlie, as a third participant in communications.

Chuck, as a third participant usually of malicious intent.

Dave, a fourth participant, and so on alphabetically.

Eve, an eavesdropper, is usually a passive attacker. While she can listen in on messages between Alice and Bob, she cannot modify them. In quantum cryptography, Eve may also represent the environment.

Isaac, an Internet service provider (ISP).

Ivan, an issuer (as in financial cryptography).

Justin, from the justice system.

Mallory, a malicious attacker; unlike Eve, Mallory can modify messages, substitute her own messages, replay old messages, and so on. The problem of securing a system against Mallory is much greater than against Eve. The names Marvin and Mallet can also be used for this role.

Matilda, a merchant (as in e-commerce or financial cryptography).

Oscar, an opponent, is usually taken as equivalent to Mallory.

Pat or Peggy, a prover, and Victor, a verifier, often must interact in some way to show that the intended transaction has actually taken place. They are often found in zero-knowledge proofs. Another name pair sometimes used is Pat and Vanna (after the host and hostess on the Wheel of Fortune television show).

Plod, a law enforcement officer (also "Officer Plod") from the children's fictional character Mr. Plod, in the Noddy books by Enid Blyton.

Steve, sometimes used in reference to steganography.

Trent, a trusted arbitrator, is some kind of neutral third party, whose exact role varies with the protocol under discussion.

Trudy, an intruder: another alternative to Mallory.

Walter, a warden, may be needed to guard Alice and Bob in some respect, depending on the protocol being discussed.

Zoe, often the last party to be involved in a cryptographic protocol.

[GreyGeek]

whew!
I think I retired just in time!