Prototype of two-factor authentication using email and a password

email-auth.rb

require 'jwe'

# Set your password and email address
key = Digest::SHA256.digest('p455w0rd!')
payload = 'aaron@parecki.com'

# Create the JWE string
encrypted = JWE.encrypt(payload, key, alg:'dir')

# Put the resulting string on your website:
# <link rel="???" href="emailauth:eyJhbGciOiJkaXIiLCJlbmMiOiJBMTI4R0NNIn0..BikmXTFB7Fcg_hhZ.Y0jDbweNGq8V3zY8gdeUFME.9i6NAgyBTHyw9P2Au55YMg">

########

# Now when a website wants to email you a challenge, in order to find the 
# email address to send to, you have to provide the encryption key to 
# allow it to decrypt the email
plaintext = JWE.decrypt encrypted, key