I understand many of us here use Steam or at least have heard of it. This is not a bitcoin service per se, but this is a service that accepts bitcoin.
If I were to lose my Steam Account tomorrow, and contact steam support, they say that I need a valid proof if purchase. Will I be allowed to sign a message from the address I paid with? Does BitPay not give Steam transaction logs, will this not count as a valid proof of purchase, or will it help me get my account back?
I have not lost my account, just asking whether I should look for something else to verify my account with in case I get hacked.
And that is very interesting question. Thanks for bringing it up. Unfortunately I don't think that steam support is that progressive to respect signed message from address used to buy product from them.
First, I am not sure if Steam support has access to bitcoin transaction logs, as Steam uses BitPay to process every BTC purchase.
Second, even if they can confirm your BTC address I am not sure if signed message is considered a proof enough - probably not.
You will still most likely still need your PayPal or Credit Card logs to prove account ownership.
But this is all my speculation, the best way is to ask Steam Support about this issue directly.