Encrypting files is actually not difficult, you can do it with GPG. GPG is an open source encryption tool that supports symmetric and asymmetric encryption methods and is suitable for protecting local files or securely exchanging data; 1. When installing GPG, Linux users can use the package manager, such as sudo apt install gnupg for Ubuntu, Homebrew for macOS: brew install gnupg, and Windows can download the installation package or use Gpg4win; 2. Check the version number and use gpg --version to ensure successful installation; 3. To symmetrically encrypt a single file, use gpg -c filename.txt, decrypt using gpg -o decrypted.txt -d filename.txt.gpg; 4. For asymmetric encryption, you need to import the other party’s public key and use gpg -e -r someone@example.com to encrypt filename.txt, and the other party uses gpg -o original.txt -d received_file.gpg decryption; 5. Clean the plain text files after encryption, and it is recommended to package and compress multiple files before encryption and then encrypt.
Encrypting files is actually not difficult, you can do it with GPG (GNU Privacy Guard). It is an open source encryption tool that supports symmetric and asymmetric encryption methods and is suitable for protecting local files or exchanging data securely with others.
Install the tool before encrypting with GPG
Whether you are using Linux, macOS or Windows, GPG has a corresponding version. Linux users can generally install through a package manager, such as on Ubuntu:
sudo apt install gnupg
Homebrew can be used on macOS:
brew install gnupg
For Windows, you can download the installation package from the official website, or use Gpg4win. After installation, it is recommended to check the version number:
gpg --version
Make sure the installation is successful and you see a list of supported algorithms in the output.
Simple encryption of a single file (symmetric encryption)
If you just want to encrypt a file for yourself and don't want to make it too complicated, you can directly use symmetric encryption. That is, set a password and use this password to decrypt later.
The operation command is as follows:
gpg -c filename.txt
After execution, you will be prompted to enter and confirm your password. After completion, a filename.txt.gpg
file will be generated. The original file is still there and you can delete it manually.
Decryption is also very simple:
gpg -o decrypted.txt -d filename.txt.gpg
It will ask you to enter a password, which if correct will restore the original content.
Send encrypted files to others? Asymmetric encryption is more appropriate
If you want to encrypt a file and send it to someone else, and the other party can decrypt it with their own private key, then you need to use asymmetric encryption. This requires you to have the other party's public key.
First import the other party’s public key:
gpg --import their_public_key.asc
Then see what keys are available:
gpg --list-keys
Find the person you want to encrypt to. Assuming his email is someone@example.com
, you can encrypt it like this:
gpg -e -r someone@example.com filename.txt
This will generate a filename.txt.gpg
file, which can only be unlocked by those with the corresponding private key.
If the other party wants to decrypt the file after receiving it, just run:
gpg -o original.txt -d received_file.gpg
This assumes they have imported their private key.
Tip: Don’t forget to clean up plain text files
Just because encryption is complete doesn’t mean everything is fine. Remember to delete the original file, otherwise others can still open it and view the content directly. Deleting files on some systems cannot completely clear them. You can use shred
or special tools to overwrite the disk space.
In addition, if it is sensitive data, it is recommended to package it into a compressed package and then encrypt it before encryption, for example:
tar -czf files.tar.gz file1 file2 gpg -e -r someone@example.com files.tar.gz
This is also convenient for uploading multiple files at once.
That's basically it. GPG has many functions, but the above methods are enough for daily encryption of files.
The above is the detailed content of How to use GPG for file encryption. For more information, please follow other related articles on the PHP Chinese website!

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