Secure hash algorithm is mainly suitable for digital signature algorithm DSA defined in digital signature standard DSS. SHA 1 will generate a message digest of 160 bits for messages with a length of less than 2 64 bits. When a message is received, the message digest can be used to verify the integrity of the data. During transmission, the data is likely to change, so different message digests will be generated at this time. SHA 1 has the following characteristics: information cannot be recovered from message digest; Two different messages do not produce the same message digest.

Used to detect the integrity of files, and can also be used to detect whether files have been changed by others.

The most important thing is to detect whether the original file of the operating system has been modified by others to prevent others from implanting viruses! Use SHA 1 to detect operating system files, and compare the generated value with the official SHA 1 value. If the same value has not been modified by others, you can install the system safely. If it is not the same, it has been modified by others. Be careful!