中文：

U盾，全称为USB Key，是网上银行常用的安全工具之一。它是一种硬件设备，通过与计算机的USB接口连接，为网上银行客户提供更高级别的安全保障。

首先，U盾可以用于身份认证。在使用网上银行进行交易时，U盾可以作为身份认证的凭证。只有持有合法有效的U盾的用户才能通过网上银行进行资金的转移或支付。这种方式可以有效地防止黑客盗取用户账户密码而进行欺诈行为。

其次，U盾可以用于加密和签名。U盾内部存储了用户的数字证书，在进行网上银行交易时，通过U盾的密码和数字证书的验证，可以将交易信息进行加密和签名，确保交易信息的完整性和安全性。这样可以有效地防止黑客截获用户交易信息而进行篡改或盗取。

此外，U盾还可以防止木马病毒的攻击。由于U盾与计算机的USB接口连接，使用U盾进行网上银行交易时，可以避免使用键盘输入用户名和密码等信息，从而防止木马病毒通过键盘记录等方式盗取用户信息。

总的来说，U盾是网上银行客户安全保障的重要工具之一，可以有效地保护用户的资金安全和隐私信息。

英文：

USB Key, also known as U盾, is one of the commonly used security tools for online banking. It is a hardware device that connects to the USB port of a computer to provide higher-level security protection for online banking customers.

Firstly, USB Key can be used for identity authentication. When using online banking for transactions, USB Key can be used as proof of identity. Only users with a valid USB Key can transfer or pay funds through online banking. This method can effectively prevent hackers from stealing user account passwords and carrying out fraudulent activities.

Secondly, USB Key can be used for encryption and signing. The USB Key stores the user's digital certificate. When carrying out online banking transactions, the transaction information is encrypted and signed through the verification of the USB Key password and digital certificate, ensuring the integrity and security of the transaction information. This can effectively prevent hackers from intercepting user transaction information and tampering or stealing it.

In addition, USB Key can also prevent the attack of trojan viruses. Since the USB Key connects to the USB port of the computer, when using online banking for transactions, it can avoid using the keyboard to enter user names and passwords, etc., thereby preventing trojan viruses from stealing user information through keyboard logging.

Overall, USB Key is an important tool for online banking customers' security protection, which can effectively protect users' financial security and privacy information.