For sensitive files or to securely send someone else a file, use OpenSSL to encrypt the file. Here’s how it works!
Encrypt a file called topsecret.txt with AES 256:
$ openssl aes-256-cbc -in topsecret.txt -out encodedtopsecret.txt enter aes-256-cbc encryption password: Verifying - enter aes-256-cbc encryption password:
Now the file encodedtopsecret.txt is a binary encrypted blob. There are no identifiable parts to this other than one thing that OpenSSL encrypted files show: ‘Salted__’ at the top when inspecting the file with the strings command. (This is how others have determined the wikileaks insurance files were encoded with OpenSSL!)
$ file encodedtopsecret.txt encodedtopsecret.txt: data
$ strings encodedtopsecret.txt Salted__ 2sHkv Rr7+ tOx* #_p%& WwlN 'fM`' 5,nn Ha(oy 1$#0 =f_>z D)@& 38yV/ p]XTyJ 10G2 ...
Now for your friend to decode this file, use tack d. OpenSSL prompts for the password the decrypts the file.
$ openssl aes-256-cbc -d -in encodedtopsecret.txt -out decodedtopsecret.txt enter aes-256-cbc decryption password: