Shulou(Shulou.com)06/02 Report--

When downloading some large files on the Internet, sometimes we will go down to a file in sfv format, which is packaged with the file we want to download. Many friends are not quite sure what this file is for, let alone how to open it, so what is the sfv file? how to open the sfv file? The following editor has brought the relevant introduction, if you are interested, let's take a look.

What file is SFV?

Shorthand for SFV (Simple File Verification) (simple file check). Literally, it is a set of simple file detection functions using CRC32 algorithm, which is suitable for various windows platforms such as Windows 95/98/NT/2000.

CRC32: CRC itself means "redundancy check code". CRC32 means that a check value of 32bit (8-bit hexadecimal number) will be generated. Because each bit (bit) of the source data block participates in the calculation when the CRC32 generates a check value, even if only one bit in the data block changes, it will get a different CRC32 value.

MD5: the name of a message digest algorithm (also known as an one-way hash function). Through a certain algorithm, it finally produces a 128bit (bit) check value (a 32-bit hexadecimal number) according to each bit of the source data. The most common application of MD5 is in cryptography, this article mainly uses it to verify the integrity of the file-if you find the above text difficult to understand, then you can simply think of MD5 as a 128bit digital signature to verify whether the file has been modified.

Users often download all kinds of files on the Internet, the most common of which are MP3, ISO, or programs compressed with all kinds of compression software. however, even if the Internet provides a reliable transmission environment, sometimes errors in the downloaded files are inevitable due to various factors, which are not exactly the same as those provided by the original uploader, and it is often difficult for users to find out. Because no original file can be compared with the downloaded file to determine whether the downloaded file is exactly the same as the one on the Internet.

Sometimes when you download, you will find that in addition to the main file, there is also a file with the .SFV file name, but it does not seem to have anything to do with the main file, in fact, the existence of this .SFV file is to solve the above problems. This file is a simple text file format, and its content is to provide additional CRC information for other files. When uploading files, the file provider uses SFV software to generate CRC information for each file and records it in a .SFV output text file. At the same time, the .SFV file is uploaded to the network with other files, and other users on the network also transmit the .SFV file back to the computer when downloading. Then the SFV software uses the contents of this file to do CRC32 testing on other files. Since its CRC32 check code will be different when there is any change in the contents of the file, it can compare this value with the CRC information of the file provider. If it is different, it means that the downloaded file is different from the original file on the network: no 100% download is complete or an error occurred in transmission. Users can download it again on the Internet.

SFV is most commonly used in RAR, MP3, ISO and other file formats.

Reference: http://www.285868.com/jiaocheng/jpc/show-10712.html

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