[CharlieTrip]

Hi, cryptography researcher here!

I'm sorry, but not having a mathematical formulation makes it extremely tedious to look into the protocol and get a feeling if it is secure or not (or if what you are doing makes even sense). If you plan to do some additional work, focus on clearly defining what you are doing for a (maths-)cryptography audience. This would definitely help!

But, I can try and give you my 2-cents after skimming the code: as far as I understand, the primitive is intrinsically sequential and encrypts chunk by chunk. Depending on the "type", you either use a stream-cipher or some OTP-like (with pad related to the hash of part of the message). You have a public way to decide (from the current chunk ciphertext?) which encryption method you use for the next chunk. Am I getting it correctly?

If this is the case, I have to admit that the OTP-like part looks weird and definitely would be the first place where to look into. Especially how the secret key is effectively expanded for the different "rounds", and if there might be some weird property for when the encryption scheme selects twice the same path.

[ciphernomad-org]

A formal spec is the next priority. We released the implementation first as the protocol is novel and we invite direct scrutiny of the work.

The path selection is secret, not public. It is determined by `hash(key, state, chunk)`. An attacker lacks the secret `key` and internal CVM `state` and cannot compute the path.

The key expansion and path collision mechanisms are as follows: 1. A round's key is derived from the master key, the CVM's state, and the unique nonce of the Labyrinth node being processed. 2. The CVM state ratchets forward after every block, making path collision negligible.

[CharlieTrip]

Despite it might sound weird, the format spec is exactly what is needed to scrutiny any cryptographic primitive. It should be the first output during the design of a security-oriented primitive/protocol. See it in this way, if you soon publish the specs and there is a massive cheese-hole, your implementation is kaput! And since security products (sometimes sadly) live in reputation-system, your product lost all the reputation regardless if it will be secure or not.

So, the path is determined step by step taking into account the initial chunk or the output chunk? I'm confused on what this "CVM state" is. Your primitive has a secret key and that it, right? Or is this state yet another secret that must be shared to use the primitive? Again, without a formal specification, it is tricky for me to understand what that "chunk" effectively is and why should allow a decryption. If chunk is the "input chunk", how can you reconstruct the same path if you do not have the input?

Wait, the "CVM state" is the "round" key? Why do you care about "path collision"? This "property" does not make any sense without some appropriate context.