In order to achieve perfect forward and perfect backward secrecy, and to counteract cryptoanalysis, the group session keys should be rekeyed.
为达到完美向前和完美向后保密以及对付密码分析，需要更新组会话密钥。
This can happen to messages being transmitted in the clear, transmitted encrypted but stored in the clear, or decryption of messages due to stolen key or cryptoanalysis.
以明文方式传输消息、传输加密的但以明文方式存储的消息、或者由于密钥被窃取或通过密码分析获取后对消息进行解密，在以上几种情况下都可能发生这种攻击。
This can happen to messages being transmitted in the clear, transmitted encrypted but stored in the clear, or decryption of messages due to stolen key or cryptoanalysis.
以明文方式传输消息、传输加密的但以明文方式存储的消息、或者由于密钥被窃取或通过密码分析获取后对消息进行解密，在以上几种情况下都可能发生这种攻击。
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