Quote from: BitMaxz on Today at 12:00:27 AM

Quote from: itsmyfirstaccount on December 15, 2023, 11:05:30 PM

As following tips
1.when I want to sign a message, do I must have the private key?

Without a private key you can't able to sign a message it is required when signing a message.

Quote from: itsmyfirstaccount on December 15, 2023, 11:05:30 PM

2.any one can using just public key to sign a message?and pass verification?

No, you can't sign a message with the public key, the private key is required because it proves that you own that wallet or that public key.

Quote from: itsmyfirstaccount on December 15, 2023, 11:05:30 PM

3.is there any trusted site or tool for signing?

I do not recommend any web tools to sign a message it's risky I recommend use Electrum Wallet instead.

Quote from: itsmyfirstaccount on December 15, 2023, 11:05:30 PM

4.how to implement it by PHP?(code better)

I don't have much knowledge in PHP but check this open source code below in PHP.

Edit:

Verify signed message in PHP
- https://github.com/Bit-Wasp/bitcoin-php/blob/master/examples/signedmessage.verify.php

Create sign message in PHP
- https://github.com/Bit-Wasp/bitcoin-php/blob/master/examples/signedmessage.create.php

You need to install the whole respiratory to make the PHP code above work.

to read the whole project is a big task.

Is there any open source, simple project which just for implement the signing function. It must be open source, no one will trust this kind of software, even Electrum .if I want to sign a message with more than 100 bitcoins, I really can not trust any software even with big companies. Do you think so?