# MSS/LMS solution The hash-based signature scheme starts with the one-time signature scheme (OTS), which means that each key pair in a signature scheme cannot be used to sign multiple messages. Currently the most effective OTS program is the Winternitz program (WOTS). The core idea of WOTS is to iteratively apply functions to secret inputs, and the number of iterations depends on the information to be signed. The Merkle signature scheme (MSS) is applicable to any cryptographic hash function and any one-time signature scheme. MSS uses a Merkle tree to connect N = 2H OTS public keys together, where H is the height of the tree. The root of the Merkle tree is used as the public key of the MSS. The algorithm used to calculate the Merkle root is called Tree hash, see Algorithm 8. In order to generate the signature of the message M, it is necessary to select the key of the next unused OTS public key and generate the OTS signature. The MSS signature includes the OTS signature, the OTS public key and the verification path used to prove the existence of the OTS public key in the Merkle tree. To verify the signature, first check the validity of the OTS signature to the OTS public key, and then verify that the OTS public key is a valid leaf of the Merkle tree with a verification path. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.heliconnft.com/technical-architecture/mss-lms-solution.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.