Note: You might want to consider using OpenSSL for file encryption instead. Please see this post.

In this post we will see how to use GnuPG to make a simple symmetric encryption and decryption. This method applies to encrypt a file so that it is unreadable.

GPG supports 11 cipher algorithms that you can use:

• IDEA
• 3DES
• CAST5
• BLOWFISH
• AES
• AES192
• AES256
• TWOFISH
• CAMELLIA128
• CAMELLIA192
• CAMELLIA256

By default, GPG will use AES256 cipher for encryption. However, you can change the cipher algorithm by supplying --cipher-also CIPHER option.

To Encrypt:

$ gpg --output encrypted.data --symmetric --cipher-algo AES256 un_encrypted.data

To Decrypt:

$ gpg --output un_encrypted.data --decrypt encrypted.data

Note: You will be prompted for a password when encrypting or decrypt.