Command line AES with openssl (and tar)

I had a script that would take a file and a passphrase and either encrypt it or, if already encrypted, decrypt it. It worked well enough and I got to play with the struct library. But it was home grown–so not compatible with anything–and didn’t properly validate anything. It worked well enough, but perhaps I could do something better.

Enter aes 2.0.

This time around, it’s just a thin wrapper around OpenSSL, originally based on the commands in this article. To encrypt a file:

dst=$src.aes
openssl enc -e -aes256 -in $src -out $dst && rm $src

To decrypt:

dst=${src::${#src}-4}
openssl enc -d -aes256 -in $src -out $dst && rm $src || (rm $dst; false)

And wrap that all up with a bit of magical filenames to do the right thing(bur for real):

for src in "$@"
do
    if [[ "$src" == *.aes ]]
    then
        echo "Decrypting $src"
        dst=${src::${#src}-4}
        openssl enc -d -aes256 -in $src -out $dst && rm $src || (rm $dst; false)

    else
        echo "Encrypting $src"
        dst=$src.aes
        openssl enc -e -aes256 -in $src -out $dst && rm $src
    fi
done

And it works great:

Excellent.

But wait…

There’s more.

if [[ "$src" == *.aesdir ]]
then
    echo "Decrypting directory $src"
    dst=${src::${#src}-7}
    (openssl enc -d -aes256 -in $src | tar xf -) && rm $src

elif [[ -d "$src" ]]
then
    echo "Encrypting directory $src"
    dst=$src.aesdir
    (tar -czf - $src | openssl enc -e -aes256 -out $dst) && rm -rf $src

...

Let’s do directories! Basically, if it’s given a directory instead of a file, tar it up then encrypt it (with a different extention). If you see that extension, decrypt it and untar it.

Recordings generated via Terminalizer with a wrapper. I’ll write that up soon™.

All in all, it’s pretty handy. I’ll have to move my files over at some point, but for now, onwards!

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