SHA 1 in win8 is a kind of digital signature verification, which is used to check whether the file is complete and whether it is re-sealed.

SHA 1, that is, 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.