Can I decrypt the EFS encrypted file after reinstalling the system?

Q: I have several important files placed in the NTFS format partition, and use the encryption function of Windows itself to encrypt the file. How to play after reinstalling the system? Do not open, how can I decrypt, open the original file? Thank you! A: In the absence of backup, it is almost impossible to decrypt EFS. Although there are many methods popular on the Internet, the feasibility is negligible. I suggest you not waste time. Because in Windows 2000/XP, each user has a SID (Security Identifier) ​​to distinguish their respective identities, each person's SID is different and unique. When encrypting the data for the first time, the operating system generates the user's key based on the SID of the encryptor, and saves the public key and the key separately for the user to encrypt and decrypt the data. If you do not back up the current key before reinstalling the system, it actually means that it is impossible to generate the previous user key anyway, and the decrypted file not only needs the public key but also the password, so it cannot be opened at all. EFS encrypted folder. You will definitely want to: re-create a same user can open? The answer is of course no, the recreated user has the same name as the previous user, but the system does not assign the same SID. remember! It is impossible to have the same SID! Unless it is a clone system. Therefore, the keys are different, and the encrypted files cannot be opened naturally.