Summary or problem description
The current Neo CLI does not support signing arbitrary messages, only transactions.
This makes it impossible to produce verifiable message signatures directly from a local wallet, which limits interoperability with external tools, dApps, and authentication flows that rely on message signing.

Do you have any solution you want to propose?
Add a new sign_message command to the CLI that allows users to sign arbitrary UTF-8 messages using any account in their loaded wallet.
The command will:

• Prompt for wallet password and verify it
• Automatically include a random 16-byte salt before the message for entropy
• Construct a deterministic payload
• Sign the payload with each account’s private key
• Output the address, public key, salt, and signature
• Optionally allow specifying the elliptic curve (secp256r1 by default, secp256k1 supported)

Where in the software does this update applies to?

• CLI