Wetsuit just wants to find out if BTC/DOGE addresses are eligible to claim
Oh, well to do that he doesn't need to even know his private keys, or share them with anyone.
The first 10k blocks in the CLAM blockchain list all the CLAM addresses which are eligible to claim, and it is possible to convert those CLAM addresses to BTC, LTC, and DOGE addresses by changing the version byte accordingly.
There were about 3.2 million CLAM addresses funded. Those correspond to 3.2 million BTC addresses. If you have a list of your BTC addresses you could make a list of funded BTC addresses, and check for matches with the list of funded BTC addresses.