在网络安全中,加密算法的用途包含以下哪几项?
A. 加密信息;
B. 防发送源抵赖;
C. 用户身份鉴别;
D. 信息完整性检测;
下面属于数字签名作用的是哪几项( )?
A. 接收者无法伪造或篡改消息;
B. 接收者可验证消息来源的真实性;
C. 可验证接收者的合法性;
D. 发送者无法否认发送过该消息;
The author’s purpose in writing this text is to explain ________.
A. why it is necessary for us to help others
B. how to help others
C. why the old and the handicapped are in need of help
D. what community service is
The main idea of Paragraph 2 is that ________
A. many people need help, but nobody cares about it
B. the organizations must defend on voluntary help
C. help should be given to those who cannot easily get it
D. organizations should be set up now to give help to those who need it
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