Quote from: n_p on August 15, 2017, 10:21:38 AM

A few years ago, I created an electrum wallet on a desktop machine with version 1.8.1.

For reasons I won't go into here, I am now limited to the android client for the foreseeable future (and beyond).

I need to sign a message (not a transaction) with the private key associated with a specific bitcoin address in that wallet.

Two questions:

1. Is there any way of doing that?

2. If not, how do I export the private key into another wallet client, so I can sign a message with it?

I can miss the obvious sometimes, but I didn't see any way of doing either of these things.

When you make a wallet, you get a seed.
You can use this seed to get the private keys and master public key. This seed can be input in the desktop version downloadable here here

To ge the seed, click the panel at the top that shows how much your balance is and press "show seed", input your pin and type that seed into you computer electrum wallet.
From here you can then sign your address by clicking tools and then sign/verify message at the top.