Ed25519 signatures

#How Ed25519 signatures work

The signer computes a signature over the exact bytes of a message, using the private key. The verifier checks that signature with the public key. If a single byte of the message changes, the check fails. Checking a signature does not reveal the private key. The scheme is deterministic, so the same message signed with the same key always gives the same signature.

#Why it matters for AI agents

Agents load tools and instructions that come from servers. A tool definition that changed without notice could send data somewhere new. A signature lets the client confirm that the content came from the key owner and was not altered after signing. That check is the reason to sign recipes at all.

#Wield and Ed25519 signatures

The Wield registry signs every index and recipe with Ed25519. The signature covers the exact response body, with a label for the kind of content and its scope. wield-mcp and the Wield extension check the signature before they use a recipe. They refuse a recipe that is unsigned, signed by an unknown key or changed after signing. The error is recipe_unsigned, and nothing is sent to the site in that case. Private recipes are signed with the organization's own key. Recipes loaded from a local folder for development are not signed, and wield-mcp doctor shows the signature status.

#Related terms

• Least privilege: the limit on what a verified recipe is allowed to do.
• Audit log: the record of which recipe ran and what it sent.
• Security model: how Wield checks signatures and where the keys come from.

#FAQ

#Why sign recipes?

A recipe tells the client which requests to send to a site. A changed recipe could send requests somewhere the user did not agree to. A signature makes any change visible, because the client refuses a recipe that does not match the registry's signature. Wield also refuses an index older than one it has already accepted, so an old version cannot be replayed.

#Ed25519 vs RSA?

Both are public-key signature schemes. Ed25519 uses short 32-byte public keys and 64-byte signatures on an elliptic curve. RSA uses much longer keys and different math. For a reader of this page, the important property is the same in both: a valid signature shows that the content came from the key owner and was not changed.