Information Security

Using GPG to password-encrypt files

In addition to public key encryption, GPG can also be used to password encrypt files. This doesn’t use public/private key encryption but uses symmetric key ciphers like AES or CAST.  This can be useful when you simply need to use a shared secret to encrypt or decrypt a file or if you are encrypting a file to yourself for safekeeping.

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Enigma Machine – Flickr Simon Claessen CC-BY

OpenSSL is cool and all but don’t use it to encrypt information in-situ. It’s a bad idea. OpenSSL is good for generating TLS certificates. It wasn’t intended for file encryption.

To encrypt a file named message.txt:

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