# Signatures and Nonces Signatures are required to safely execute orders in the name of your wallet. The API endpoints for order management require a user signature that must be created on the client side using your private key. These signatures are validated on-chain for all order details you specified to ensure no unintended action is executed on your account. Internal nonces for your wallet address, tracked in the smart contracts, are used to prevent replay attacks. Creating your own signatures and nonces can be a bit tricky, and a single detail being wrong will result in an "invalid signature" error which are notably hard to debug. Our recommendation is to check our python SDK's code to fully understand every detail on how signatures need to be produced. --- # 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.reya.xyz/developers/readme/signatures-and-nonces.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.