What is MD5?

What is MD5?

MD5 is the abbreviation of message-Digest algorithm 5 (Information-Digest algorithm). It is widely used in encryption and decryption technology. It can be said to be a "digital fingerprint" of a file ". Any file, whether it is an executable program, image file, temporary file, or any other type of file, no matter how large it is, has only one unique MD5 information value, and if the file has been modified, its MD5 value will also change. Therefore, we can verify whether the file has been "Tampered" by comparing the MD5 value of the same file.
What is the use of MD5?
If you want to know whether the downloaded file is exactly the same as the original file on the website, you can perform MD5 verification on the downloaded file. If the MD5 value is the same as that published on the website, you can confirm that the downloaded file is complete. If there are differences, the downloaded file is incomplete: either an error occurs during the network download process, or the file has been modified by others. It is recommended that you do not use the virus to prevent others from modifying the file.
When we use e-mail to send a file to a friend, we can send the MD5 value of the file to the other party so that the friend can verify the file after receiving it to determine whether the file is secure.
Another example: after installing the system, you can perform MD5 verification on the system files. After a while, if you suspect that some files have been replaced, then we can perform MD5 verification on the suspected files. If the MD5 verification code is different from the previously obtained MD5 verification code, it is certainly a problem.
How to read and verify MD5 Information
After learning about the MD5 information, let's take a look at how to read and verify the MD5 information of the file. This requires a specialized small software for MD5 value detection. This is a green software. After decompression, run the md5.exe file. The software is very easy to use. Click "open" to select and open the file to be verified. After a moment, the MD5 value of the file will be displayed in the MD5 column, compare the value with the Value published on the website to determine whether the file is complete. Click the "save" button to save the read MD5 as A. MD5 file. use NotePad to open the file and copy the MD5 value.
In order to verify whether the modified MD5 value of the file has changed, I used a text file for testing. 2. The first file is the original file for testing, and the second file is the modified file (but only a space is added on the basis of opening the original file ), the third object is the copy object of the original object. It can be seen that the MD5 values of the two files are quite different, but the copied files do not change.