Pull in Viget posts

content/elsewhere/simple-secure-file-transmission/index.md

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+---
+title: "Simple, Secure File Transmission"
+date: 2013-08-29T00:00:00+00:00
+draft: false
+needs_review: true
+canonical_url: https://www.viget.com/articles/simple-secure-file-transmission/
+---
+
+Often I need to send a file containing sensitive information, like a
+database dump or a digital certificate, to a client or fellow developer.
+It's difficult to know the correct level of paranoia to exhibit in
+situations like these. Obviously, nobody's sitting in front of a
+computer in a dark room, just *waiting* for me to leak the SSL
+certificate for the staging Solr EC2 box. At the same time, I know there
+are many people with access to my email, my Dropbox, my Basecamp posts,
+and it would be irresponsible of me to rely on their collective good
+faith to keep this information secure.
+
+I've settled on a simple solution that doesn't inconvenience the sender
+or receiver too terribly much (assuming they're both on modern,
+Unix-compatible machines) while making things considerably more
+difficult for any would-be eavesdroppers. Suppose I want to send an AWS
+PEM certificate to [Chris](https://viget.com/about/team/cjones),
+disregarding the fact that he's sitting maybe four feet from me right
+now. Here's what I'd do:
+
+### Step 1: Encrypt with OpenSSL
+
+I have a short shell script, `encrypt.sh`, that lives in my `~/.bin`
+directory:
+
+    #!/bin/sh
+
+    openssl aes-256-cbc -a -salt -pass "pass:$2" -in $1 -out $1.enc
+
+    echo "openssl aes-256-cbc -d -a -pass \"pass:XXX\" -in $1.enc -out $1"
+
+This script takes two arguments: the file you want to encrypt and a
+password (or, preferably, a [passphrase](https://xkcd.com/936/)). To
+encrypt the certificate, I'd run:
+
+    encrypt.sh production.pem 
+    "I can get you a toe by 3 o'clock this afternoon."
+
+The script creates an encrypted file, `production.pem.enc`, and outputs
+instructions for decrypting it, but with the password blanked out.
+
+### Step 2: Send the encryped file
+
+From here, I'd move the encrypted file to my Dropbox public folder and
+send Chris the generated link, as well as the output of `encrypt.sh`,
+over IM:
+
+![](http://i.imgur.com/lSEsz5z.jpg)
+
+Once he acknowledges that he's received the file, I immediately delete
+it.
+
+### Step 3: Send the password (via another channel)
+
+Now I need to send Chris the password. Here's what I **don't** do: send
+it to him over the same channel that I used to send the file itself.
+Instead, I pull out my phone and send it to him as a text message:
+
+![](http://i.imgur.com/pQHZlkO.jpg)
+
+Now Chris has the file, instructions to decrypt it, and the passphrase,
+so he's good to go. An attacker, meanwhile, would need access to both
+his Google chat and iOS messages, or at least a sweet [\$5
+wrench](http://xkcd.com/538/). (Friday is two-for-one XKCD day, in case
+you missed the sign out front.)
+
+------------------------------------------------------------------------
+
+So that's what I've been doing when I have to send private files across
+the network. I'm sure a security expert could find a hundred ways that
+it's insufficient, but I hope said strawman expert would agree that this
+is a much better approach than sending this information in the clear.
+I'm curious what others do in these types of situations -- let me know
+in the comments below.