Inspired by logxing's proposal, i come up with an idea which may completely solve this potential security issue. if we could use the signature which sign on the specified text(e.g the donation address) with private key, to claim the corresponding shares in different DACs,then we would not worry about private key stolen,as we do NOT need to expose our private key and use different signature to claim the shares in different DAC. e.g signature to claim the XTS shares =sign(“XTS”+Pts/BTC donation address, PrivateKey), signature to claim the DNS shares =sign(“DNS”+Pts/BTC donation address, PrivateKey)