数据块使用一个对称密钥算法进行加密，它使用一个密钥来实现对数据的加密和解密。

The bulk of the data is encrypted using a symmetric key algorithm that encrypts and decrypts data using a single secure key.

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对称算法非常有效，并且可以与用于加密和解密计算的单一密钥一起使用。

Symmetric algorithms are very efficient and work with a single key for both encryption and decryption calculations.

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用于数据加密的密钥是使用带有与服务提供者（Service Provider）的 X.509 证书相关联的公钥的非对称算法进行加密的。

The key used for the data encryption is encrypted itself using an asymmetric algorithm with the public key associated with the Service Provider's X.509 certificate.

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