signmessage "address" "message"

The signmessage RPC signs a message with the private key of an address.

*bitcoin-cli help signmessage

signmessage "address" "message"

Sign a message with the private key of an address
Requires wallet passphrase to be set with walletpassphrase call if wallet is encrypted.

1. address    (string, required) The bitcoin address to use for the private key.
2. message    (string, required) The message to create a signature of.

"str"    (string) The signature of the message encoded in base 64


Unlock the wallet for 30 seconds
> bitcoin-cli walletpassphrase "mypassphrase" 30

Create the signature
> bitcoin-cli signmessage "1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX" "my message"

Verify the signature
> bitcoin-cli verifymessage "1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX" "signature" "my message"

As a JSON-RPC call
> curl --user myusername --data-binary '{"jsonrpc": "1.0", "id": "curltest", "method": "signmessage", "params": ["1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX", "my message"]}' -H 'content-type: text/plain;'