How to export public key for an address in bitcoin-qt?

Question

With the probable increase in demand for multi-sig (P2SH) addresses, and since the procedure for creating such addresses requires that each participant provides the uncompressed public key for an address under their control, I find it surprising hard to find documentation on how to export the public key of a bitcoin address.

So for the benefit of future searches: How exactly to you get the public key for an existing address for which you have a private key in bitcoin-qt?

Answer 1

And the answer is:

1. copy the address in question from your "Receive" address list
2. Help -> Debug window -> Console
3. type: validateaddress <address>

where <address> is the address you copied in step 1.

The command validateaddress will output a number of key-value pairs, one of them being "pubkey".

Edit: bitcoin-qt creates compressed keys (as you can check in the iscompressed key-value). If you need uncompressed keys you can use something like https://coinb.in/

Answer 2

I'd like to give a general answer that can apply to any wallet. As long as you have the private key, you can get the public key easily.

You can convert any private key to a public key using pybitcointools. After you install pybitcointools using pip install pybitcointools, simply run python and issue the following commands:

import bitcoin
bitcoin.privtopub('57c617d9b4e1f7af6ec97ca2ff57e94a28279a7eedd4d12a99fa11170e94f5a4')

Of course, you will have to replace your private key in the above statement.