Quick Summary
jass(1) is a tool to let you encrypt/decrypt data using SSH keys. Keys can be provided locally, fetched from LDAP, retrieved from GitHub, or via any external command.
Encryption:
$ jass -u jschauma <service.yml | \
mail -s "Please do the needful!" jschauma
Decryption:
jass -d -k ~/.ssh/privkey <secret
Please see the manual page for further details.
Installation
If you like to live fast and fetch binaries from the internet, you can install jass(1) via e.g.:
$ curl -s https://raw.githubusercontent.com/jschauma/jass/master/src/install.sh | sh
This will fetch the binary and manual page and attempt
to install it under ${PREFIX}. If you don't have
write access to ${PREFIX}, add sudo(8) before sh.
If you're on Mac OS X, you can install this package (M1 / arm64); that package is signed with my PGP key 6F6BD3D7 with the signature here.
$ cd packages/dmgs
$ gpg --verify jass.dmg.asc jass.dmg
gpg: Signature made Wed Oct 23 16:55:04 2019 EDT using RSA key ID 6F6BD3D7
gpg: Good signature from "Jan Schaumann <[email protected]>"
gpg: aka "Jan Schaumann (@jschauma) <[email protected]>"
gpg: aka "Jan Schaumann <[email protected]>"
$ hdiutil mount -quiet jass.dmg
$ sudo installer -pkg /Volumes/Jass/jass-7.1.pkg -target /
installer: Package name is jass-7.1
installer: Upgrading at base path /
installer: The upgrade was successful.
$ hdiutil unmount /Volumes/Jass
"/Volumes/Jass" unmounted successfully.
$
Manual installation
$ make build
If you like, you can install the binary and the manual page somewhere convenient; the Makefile defaults to '/usr/local' but you can change the PREFIX:
$ make PREFIX=~ install
Details
Sharing Secrets
Every now and then we have a need to share a "secret" with some co-workers. Coordinating this can be problematic, since you would either need to be in the same physical space at the same time, or you would need to be able to talk over the phone (and know that who you're talking to is in fact the person you think you're talking to) etc. etc.
Wouldn't it be nice if you could just attach the file in question to an email, insert it into a ticketing system, or drop it on a shared host?
Using SSH Keys
Many organizations already use SSH keys for access to their hosts. That is, you have a central place (local file systems on shared hosts as well as, perhaps, LDAP) where you have public keys that you already trust to belong to the given person. Most engineers are familiar with ssh(1) and the use of ssh keys for authentication, but what not everybody might be aware of is that by their very nature these keys can also be used for encryption of non-SSH related data.
jass(1) does just that. It supports encryption for multiple keys and should generally be reasonably "user friendly".
Finding keys
You can specify the public key(s) to encrypt data for on the command-line. Alternatively, jass(1) can try to fetch the key(s) for a given user or members of a Unix group from LDAP, GitHub (public or internal), or an external command.
GitHub Service
By default, jass(1) will look for keys for the recipients on GitHub. It
does so by retrieving the URL https://api.github.com/users/<user>/keys.
If you prefer this not to happen, set the GITHUB_URL environment variable
to the empty string.
Alternatively, you can set GITHUB_URL to e.g., an internal GitHub
service endpoint such as https://git.your.domain.com/api/v3, and jass(1)
will look for keys there. This also will work for specifying a GitHub
"team" instead of a group, either in the format "org/team" or as a numeric
team-id.
If you are using an internal GitHub service and require authentication,
you can set the GITHUB_API_TOKEN environment variable to enable Basic
HTTP Auth. This token will require read:org and read:user
privileges.
External Commands
The perhaps easiest way to customize SSH public key retrieval for your environment is to use a separate external command or shell script. For example, if you have an internal server where you can fetch SSH pubkeys via a client-cert authenticated HTTP GET, you might do the following:
$ cat > ~/bin/fetchkeys <<EOF
#! /bin/sh
curl --cert ~/.cert/cert.pem --key ~/.cert/key.pem \
https://internal.example.com/pubkeys/$1
EOF
$ chmod +rx ~/bin/fetchkeys
$ export PATH=~/bin:$PATH
$ jass -c fetchkeys -u recipient <data
The command passed to jass(1) via -c will be invoked with the
recipient name as the single argument.
The advantage of this is that with an external command, there is no limit
on the complexity of what you might need to do to find the keys without
having to code those details into jass(1).
How to use jass(1)
Encrypting data
To encrypt the file service.yml for the local user jschauma and send it via email:
$ jass -u jschauma <service.yml | \
mail -s "Please do the needful!" jschauma
If you do not have a user named 'jschauma' on your local systems, nor in LDAP (if you set that up), then by default jass(1) will look for that user's keys on GitHub.
For example, to encrypt a message for Linus Torvalds using his GitHub key, you might run:
$ echo "0-day in ext4, ping me for details" | jass -u torvalds
Please see the manual page for details and other examples.
Decrypting data
To decrypt data, you need to have access to the private ssh key in question. This means that this should not happen on a shared box but instead is likely to occur on your desktop, laptop or other private system:
jass -d -k ~/.ssh/privkey <secret
Providing Passphrases
jass(1) allows you to specify the passphrase for your private key as
well as for querying LDAP via several methods. It is strongly recommended
to use one of the options involving a password manager.
For example, on macOS you might want to add your LDAP password and SSH key passphrase to the keychain as described here:
$ security add-generic-password -a ${USER} -s ldap -w
password data for new item:
retype password for new item:
$ security add-generic-password -a ${USER} -s sshkey-internal -w
password data for new item:
retype password for new item:
$
With those items in the keychain, you'd then use jass(1) as follows:
# To encrypt:
$ echo "secret message" | jass -p keychain:ldap -u jschauma
# To decrypt:
$ <secret-input-file jass -d -p keychain:ssh-key -k ~/.ssh/mykey
You might then use some aliases to save yourself some typing:
$ cat >>~/.bashrc <<EOF
alias jass-e='jass -p keychain:ldap'
alias jass-d='jass -d -p keychain:ssh-key -k ~/.ssh/mykey
EOF
$ . ~/.bashrc
$ echo "secret message" | jass-e -u ${USER} | jass-d
secret message
$
jass(1) also supports the
1Password and
LastPass key managers by way
of their respective command-line interfaces.
Supported Platforms
jass(1) is written in Go, so it should run pretty much anywhere that you
can build a binary for. (An older version of jass(1) written in shell is
also available in the 'src' directory, but that is largely for historical
purposes.)
FAQ
Why don't you just use PGP?
Why indeed. PGP has many advantages and more widespread use would make things a lot easier, but very few people appear to use it. SSH keys, on the other hand, are used nearly everywhere.
Why does this ask me for my passphrase when decrypting? Can't it get it from my ssh agent?
Unfortunately the key available in any possible ssh agent cannot be used
by jass(1), since we are not actually using ssh(1) at all: we just happen to
use an SSH key. If the key is encrypted, then we need to prompt the user
for the passphrase.
Why can't I use ECDSA or DSS keys?
DSA (or DSS) and ECDSA are digital signature algorithms, not
encryption algorithms. jass(1) uses AES for the actual data encryption,
but it then encrypts a session key using RSA, and thus only supports (at
this time, anyway) RSA SSH keys.
Who wrote this tool?
jass(1) was originally written by Jan Schaumann ([email protected]) in
April 2013.
You can read more about its historical evolution here: