There is no need to re-download Win8.1 MSDN version

Computer store news: 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. 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.

Here is a science:

Tip 1: What is the hash of the file? What is SHA1? What is the role?

File hashes —— We can simply interpret this as a string of characters obtained by computing a file 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.

Tip 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://| File| Aa….aa| Bb…..bb| Cc……cc| /

where "aa….aa” part indicates the file name, which can be changed at will; "bb…..bb” part indicates the file size (bytes); the most critical is "cc…&hellip ;cc” section. The cc……cc” part is actually a hash of the file (ie ed2k hash algorithm, a variant of the MD4 algorithm). If you do not consider the file name (the name is free to change, does not affect the download results. Remember to download the gourd XX as a farce?), because the file hash value is unique, so a file ed2k share link In fact, since the birth of the document, it has been uniquely determined.

So how did the ed2k link come about? It's very simple, just download the authentic eDonkey client (foreign. The basics in the country have become a squat), and share the files on your computer to automatically generate the ed2k link. Or calculate the ed2k hash of the file, you can get the ed2k link address by combining it yourself.

To understand, the network disk sharing, or ed2k and other download forms are based on the file hash algorithm to identify the file. Even if someone re-shares the MSDN original image, because the network disk upload will definitely pass, so the file is still the file, changed the name; and the ed2k link only recognizes the hash value, regardless of the file name, so you download the source and download the file. There is no difference before, and the download result is naturally the same.