8.3 KiB
Mailvelope Keyserver 
A simple OpenPGP public key server that validates email address ownership of uploaded keys.
Why not use Web of Trust?
There are already OpenPGP key servers like the SKS keyserver that employ the Web of Trust to provide a way to authenticate a user's PGP keys. The problem with these servers are discussed here.
Privacy
The web of trust raises some valid privacy concerns. Not only is a user's social network made public, common SKS servers are also not compliant with the EU Data Protection Directive due to lack of key deletion. This key server addresses these issues by not employing the web of trust and by allowing key removal.
Usability
The main issue with the Web of Trust though is that it does not scale in terms of usability. The goal of this key server is to enable a better user experience for OpenPGP user agents by providing a more reliable source of public keys. Similar to messengers like Signal, users verify their email address by clicking on a link of a PGP encrypted message. This prevents user A from uploading a public key for user B. With this property in place, automatic key lookup is more reliable than with standard SKS servers.
This requires more trust to be placed in the service provider that hosts a key server, but we believe that this trade-off is necessary to improve the user experience for average users. Tech-savvy users or users with a threat model that requires stronger security may still choose to verify PGP key fingerprints just as before.
Standardization and (De)centralization
The idea is that an identity provider such as an email provider can host their own key directory under a common openpgpkeys subdomain. An OpenPGP supporting user agent should attempt to lookup keys under the user's domain e.g. https://openpgpkeys.example.com for user@example.com first. User agents can host their own fallback key server as well, in case a mail provider does not provide its own key directory.
Api
The key server provides a modern RESTful api, but is also backwards compatible to the OpenPGP HTTP Keyserver Protocol (HKP).
HKP api
The HKP apis are not documented here. Please refer to the HKP specification to learn more. The server generally implements the full specification, but has some constraints to improve the security for automatic key lookup:
Accepted search parameters
- Email addresses
- V4 Fingerprints
- Key ID strings with at least 16 digits (64-bit long key ID)
Accepted op parameters
- get
- index
- vindex
Accepted options parameters
- mr
REST api
Lookup a key
By ID (hex long key id or fingerprint)
GET /api/v1/key?id=b8e4105cc9dedc77
By email address
GET /api/v1/key?email=user@example.com
By email address (shorthand link for sharing)
GET /user/user@example.com
Payload (JSON):
{
"keyId": "b8e4105cc9dedc77",
"fingerprint": "e3317db04d3958fd5f662c37b8e4105cc9dedc77",
"userIds": [
{
"name": "Jon Smith",
"email": "jon@smith.com"
}
],
"created": "Sat Oct 17 2015 12:17:03 GMT+0200 (CEST)",
"algorithm": "rsa_encrypt_sign",
"keySize": "4096",
"publicKeyArmored": "-----BEGIN PGP PUBLIC KEY BLOCK----- ... -----END PGP PUBLIC KEY BLOCK-----"
}
- keyId: The 16 char key id in hex
- fingerprint: The 40 char key fingerprint in hex
- userIds: An array of the public key's user IDs
- created: The key creation time as a JavaScript Date
- algorithm: The primary key alogrithm
- keySize: The key length in bits
- publicKeyArmored: The ascii armored public key block
Upload new key
POST /api/v1/key
Payload (JSON):
{
"publicKeyArmored": "-----BEGIN PGP PUBLIC KEY BLOCK----- ... -----END PGP PUBLIC KEY BLOCK-----",
"primaryEmail": "user@example.com"
}
- publicKeyArmored: The ascii armored public PGP key to be uploaded
- primaryEmail (optional): The ascii armored block is parsed to check for user ids, so this parameter is purely optional. Normally a verification email is sent to every user id found in the pgp key. To prevent this behaviour, user agents can specify the user's primary email address to send out only one email.
Verify uploaded key
GET /api/v1/verify?id=b8e4105cc9dedc77&nonce=123e4567-e89b-12d3-a456-426655440000
Request key removal
By key id
DELETE /api/v1/key?id=b8e4105cc9dedc77
By email address
DELETE /api/v1/key?email=user@example.com
Verify key removal
GET /api/v1/verifyRemove?id=b8e4105cc9dedc77&nonce=123e4567-e89b-12d3-a456-426655440000
Development
The server is written is in JavaScript ES6 and runs on Node.js v4+. It uses MongoDB v2.4+ as its database.
Install Node.js (Mac OS)
This is how to install node on Mac OS using homebrew. For other operating systems, please refer to the Node.js download page.
brew update
brew install node
Setup local MongoDB (Mac OS)
This is the installation guide to get a local development installation on Mac OS using homebrew. For other operating systems, please refer to the MongoDB Getting Started Guide.
brew update
brew install mongodb
mongod --config /usr/local/etc/mongod.conf
Now the mongo daemon should be running in the background. To have mongo start automatically as a background service on startup you can also do:
brew services start mongodb
Now you can use the mongo CLI client to create a new test database. The username and password used here match the ones in the config/development.js file. Be sure to change them for production use:
mongo
use keyserver-test
db.createUser({ user:"keyserver-user", pwd:"trfepCpjhVrqgpXFWsEF", roles:[{ role:"readWrite", db:"keyserver-test" }] })
Setup SMTP user
The key server uses nodemailer to send out emails upon public key upload to verify email address ownership. To test this feature locally, open the config/development.js file and change the email.auth.user and email.auth.pass attributes to your Gmail test account. Make sure that email.auth.user and email.sender.email match. Otherwise the Gmail SMTP server will block any emails you try to send. Also, make sure to enable Allow less secure apps in the Gmail security settings. You can read more on this in the Nodemailer documentation.
For production you should use a service like Amazon SES, Mailgun or Sendgrid. Nodemailer supports all of these out of the box.
Install dependencies and run tests
npm install && npm test
Start local server
npm start
Production
The config/development.js file can be used to configure a local development installation. For production use, the following environment variables need to be set:
- NODE_ENV=production
- MONGO_URI=127.0.0.1:27017/test_db
- MONGO_USER=db_user
- MONGO_PASS=db_password
- SMTP_HOST=127.0.0.1
- SMTP_PORT=465
- SMTP_TLS=true
- SMTP_STARTTLS=true
- SMTP_PGP=true
- SMTP_USER=smtp_user
- SMTP_PASS=smtp_pass
- SENDER_NAME="OpenPGP Key Server"
- SENDER_EMAIL=noreply@example.com
License
AGPL v3.0
See the LICENSE file for details
Libraries
Among others, this project relies on the following open source libraries: