In case of a compromise of one of your devices, an attacker can spend coins from your wallet. Checking your balance might reveal to you thatwhether your device has eventually been compromised. If a coin has been spent, this coin cannot be spent a second time. The Exchange examines every coin whether it has been spent and thus makes double spending impossible.
GNU Taler must be <a href="https://www.gnu.org/philosophy/free-sw.html">Free/Libre Software</a>. For merchants, Free/Libre Software prevents vendor lock-in meaning merchants can easily choose another service provider to process their payments. For countries, Free/Libre software means GNU Taler can not compromise sovereignty by imposing restrictions or requirements. And for exchange operators, transparency is crucial to satisfy <a href="https://en.wikipedia.org/wiki/Kerckhoffs's_principle">Kerckhoff's principle</a> and to establish public confidence.
GNU Taler 必須是<a href="https://www.gnu.org/philosophy/free-sw.html">自由軟體</a>。對於商家來說,自由軟體防止供應商鎖定(lock-in),這意味著商家可以輕鬆選擇其他服務提供商來處理他們的付款。對於國家來說,自由軟體意味著 GNU Taler 無法通過施加限制或要求來損害其主權。對於交易所運營商而言,透明度對於滿足<a href="https://en.wikipedia.org/wiki/Kerckhoffs's_principle">Kerckhoff's principle</a>尤其重要,這也能建立公眾的信心。