res.sendFile support for encrypted files

[ediweissmann]

I'd like to be able to serve encrypted files with res.sendFile().
Maybe by passing a decrypting stream via opts, that is piped along with the file contents?

Thanks.

[dougwilson]

Hi! Would you be willing to flesh out the proposal a bit more so we can understand what would need to be implemented to support your use-case? You're also definitely welcome to start up a PR even if it's incomplete if that is a more preferred way to start on a proposal (code vs words) :)

[ediweissmann]

Hi,

Use-case is:

• files are stored encrypted on disk.
• I'd like to use res.sendFile() and pass a transforming stream, that decrypts the files.

var decrypt = crypto.createCipher(algorithm, password);
var opts = {
  transform: function(stream) { 
    return stream.pipe(decrypt);
  }
}
res.sendFile(path, opts, cb);

I've tried implementing this in an Express PR.
Realised Express uses pillarjs/send for the file streaming.
So, support for transforming streams would first need to land in pillarjs/send.
Noticed one open PR exists on the subject.
Options already are passed through, so no change required in Express.

[dougwilson]

Ah, good catch on that send PR. I added a comment for an issue it has, which I believe would be an issue if you are trying to decrypt files as well.

[ediweissmann]

Thanks, your comment was very helpful.