Why is it unnecessary to re-download the Win8.1 MSDN version?

        Microsoft today opened the official version of Win8.1 image download to MSDN subscribers. After comparison, it has been confirmed that the image is completely consistent with the leaked image. So, if you have downloaded the leaked image (that is, the Russian one), you don't need to download it again. However, there are always many friends who have obsessive-compulsive disorder. Be sure to download the original version of Win8.1 MSDN. If you don't feel so uncomfortable.

Come here to science:
Little knowledge 1: What is the hash of the file? What is SHA1? What is the role?
File hash value - we can simply understand it as: a string of characters obtained by computing a file data using a special algorithm. There are many such algorithms. For each algorithm, a file corresponds to a unique hash value, but not necessarily the other way around. However, for a good algorithm, because its back-calculation is almost impossible to achieve, that is, it is almost impossible to forge a file with the same hash value based on the hash value of a file, so we think the hash is the same. The file is the same file, and it is completely possible to judge the correctness and completeness of the file based on the hash value. Commonly used file hashing algorithms are: MD2, MD4, MD5, SHA1, and so on. People often judge the authenticity or integrity of a document based on the MD5 and SHA1 of the file.
Little knowledge 2: How is the ed2k link generated? - Science
Take a closer look at the ed2k link form, and you'll find that these links follow a specific format. The basic ed2k link form for a file resource is:
ed2k://