The alternative is symmetric encryption, but with symmetric encryption you must have a secret key known only to the parties involved in a message exchange.

另外一种方法是对称加密，但是使用对称加密时，您必须拥有只有参与消息交换各方才知道的密钥。

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An asymmetric key (public key) algorithm is used for the exchange of the secret keys to be used in symmetric algorithm and for digital signatures.

对称密钥(公钥)算法用于交换在对称算法中使用的加密密钥，以及用于数字签名。

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