The key logger allows an attacker to hijack any user input; for example, if a user uses a Web-based e-mail service, the key logger will record and transmit any text input to the attacker.

键盘记录工具允许攻击者劫持任何用户输入；比如说，如果某个用户在使用一个基于 Web 的电子邮件服务，那么键盘记录工具将记录下任何文本输入并将其发送给攻击者。

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The United States Post Office did not require the Letter Logger to do this, however, in part because mail often travels in aircraft, and transmitting devices must be switched off during take-off and landing.

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