When encountering an encrypted file, you must first identify the encryption type and then use the corresponding tool to decrypt it. 1. Confirm the encryption method, such as GPG or OpenSSL encryption, through file extension or file command; 2. To decrypt GPG files with gpg command, you need to enter a password or private key, such as gpg -o output_file -d encrypted_file.gpg; 3. OpenSSL decryption requires specifying algorithm mode such as openssl aes-256-cbc -d -in encrypted_file.enc -out decrypted_file; 4. File system encryption, such as eCryptfs login, automatically decrypts the compressed package, you can enter the password to decompress. Master the correct tools and parameters to complete the decryption.
It is not mysterious to encounter encrypted files that need to be decrypted. The Linux system itself provides many tools and methods to handle common types of encrypted files. The key is to know what tools to use and how to use them.
Identifying encryption is the first step
Before trying to decrypt, you must first figure out how the file is encrypted. Different encryption methods correspond to different decryption methods. Common encryption types include:
-
.gpg
files encrypted using GPG - Files encrypted with OpenSSL usually have no specific suffix or end with
.enc
- File system-level encryption (such as eCryptfs)
- Encryption package generated by third-party encryption software
If you are not sure about the encryption method, you can first look at the file extension or use file
command to view the file type, such as:
file encrypted_file
Sometimes information like "GPG symmetrically encrypted data" or "OpenSSL AES-256 encrypted data" will be returned, which can help you determine what to do next.
Use GPG to decrypt GPG encrypted files
If you confirm that it is a GPG encrypted file and you have a password or private key, you can directly use the gpg
command to decrypt it. for example:
gpg -o output_file -d encrypted_file.gpg
The meaning of this command is: use GPG to decrypt encrypted_file.gpg
and save the result to output_file
. During execution, you will be prompted to enter your password (if encrypted with a password), or you will automatically use your private key (if it is asymmetric encryption).
Notice:
- If the original file name is preserved, you can use
--set-filename
to specify the output file name - If there is no
-o
parameter, the decrypted content will be output to the terminal by default, which is easy to see
Decrypt AES encrypted files with OpenSSL
OpenSSL is another commonly used encryption/decryption tool, and many scripts or programs like to use it for symmetric encryption. For example, a file encrypted with AES-256-CBC, you can decrypt it like this:
openssl aes-256-cbc -d -in encrypted_file.enc -out decrypted_file
You will be prompted to enter your password when executing. If there is no correct password, the decrypted file will be garbled.
But be aware:
- Must know the encryption algorithm and mode (such as aes-256-cbc)
- If salt is used during encryption, no additional specification is required in the command, OpenSSL will automatically recognize it
- If you get the encrypted file from someone else, remember to confirm which parameters they are using, otherwise it will be difficult to restore.
Other cases: File system encryption and compressed package encryption
Some encryptions are not individual file encryption, but come from file system hierarchy or compressed packages. For example:
- eCryptfs : This is the home directory encryption mechanism that Ubuntu once used by default. This type of encryption is usually transparent, and you can see the plain text as long as you log in to the user, and there is no need to decrypt it manually.
- ZIP/RAR encryption : Use
unzip
or7z
tools to directly enter the password to decompress. For example:
7z x encrypted.zip
You will be prompted to enter your password. However, it should be noted that some ZIP encryption has low strength and is easily brute-forced; while RAR5 encryption is relatively safe.
Basically that's it. The corresponding tools for different encryption methods are slightly different, but there are basically ready-made command support on Linux. As long as you understand the encryption source and match the correct password or key, the decryption process is not complicated, but sometimes it is easy to ignore the encryption details.
The above is the detailed content of How to decrypt files on Linux. For more information, please follow other related articles on the PHP Chinese website!

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