(2016·全国卷Ⅰ)
话题:信息安全 词数:295W 难度:★★★
Secret codes(密码)keep messages private. Banks, companies, and government agencies use secret codes in doing business, especially when information is sent by computer.
People have used secret codes for thousands of years. 36 Code breaking never lags(落后)far behind code making. The science of creating and reading coded messages is called cryptography.
