1.
An Abuse-Resistant
Messaging Protocol
Jim Fenton
fenton@bluepopcorn.net
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2.
Problem
• Limits on abuse resistance of existing
general-purpose protocols
• Email, SMS, telephone
• Anti-abuse features run afoul of some use
cases
• Need to accept either collateral damage or
limits on protocol usage
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3.
Approach
• Migrate subset of messaging use cases
• New abuse-resistant protocol
• Focus on high value use cases
• Need value for both senders and
recipients to prompt migration
(migration is hard!)
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4.
Value
• Moving messaging to an abuse-resistant
protocol decreases fraud
• Messages sent using legacy protocols
eventually become “suspicious”
• Narrower protocol may also better serve
certain use cases
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5.
Proposed use case:
Notifications
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6.
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7.
Desired Characteristics
• Recipient:
• Opt-in only
• Prioritized
• Authenticated
• Expire or deleted
when not relevant
• Timely
• Unsubscribable
• Configurable “push"
• Sender:
• Receipt confirmation
• Intermediaries not
needed
• Possible with modest
originator, e.g. IoT
• Update or delete
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8.
What is a Nōtif?
• Nōtif : notification :: app : application
• Tell a user that something they’re
interested in is happening or has happened
• Requested by the user
• Typically time-sensitive, perishable
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9.
What a Nōtif isn’t
• Anything unsolicited
• correspondence
• spam
• Addressed by a human
• addresses are unsuitable for that
• Two-way
• Multihop
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10.
Nōtifs Manifesto
• Users:
• Should have control over what nōtifs they receive
• Should be able to know that the nōtifs they receive are genuine
• Should have control over if and how they are alerted when
nōtifs arrive
• Should not have to reveal information about themselves just to
receive nōtifs
• Notifiers:
• Should not have to guess whether nōtifs are being delivered
• Should not have to employ intermediaries to get nōtifs delivered
• Should be able to amend or delete nōtifs to keep them relevant
• Nōtifs:
• Should expire and hide when no longer relevant
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11.
Notifiers
Agent
User endpoints
Notification
Agent
Phone
CallSMS,
App push
Growl
Management,
Authorization
Notifications
Authorization Table
Rules
Bank Emergency
Services
RetailersSocial Media
Approval
Requests
Calendar
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12.
Notifiers
• Typically not operated
by user
• Opt-in by user through
authorization ceremony
• May or may not know
much about the user
• Examples:
• Emergency services
• E-Commerce sites
• Social media
• Enterprise services
• Reminders
• IoT sensors
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13.
Nōtif Agents
• Operate on behalf of
user
• Cloud-based
• User-chosen,
decentralized
• Store notifications for
retrieval by user
• Manage authorizations
for user
• Analogous to last-hop
MTA/MDA
• Alert user to specific
notifications of
particular interest or
urgency
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14.
User endpoints
• Push
• Mobile device app
(push notification)
• SMS
• Voice (telephone)
• Desktop app
• Email (!)
• Pull
• Web interface
• Email-like (IMAP)
• Mobile app (via future
API)
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15.
Nōtif Authorizations
• A record of a relationship between a notifier and a user
• Contains:
• Notification address
• Notifier’s domain
• Description (provided/edited by user)
• Max authorized priority
• Tags
• Flags (active, deleted, etc.)
• Statistics (count, etc.)
• Link to user (internal)
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16.
Authorizing
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17.
Authorizing - 2
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18.
Authorizing - 3
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19.
Nōtif Summary
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20.
Nōtif Detail
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21.
Nōtif (IMAP)
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22.
Authorization Summary
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23.
Authorization
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24.
Methods
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25.
Alert Rules
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26.
Current status
• Prototype Nōtif agent up and running
• Linux/PostgreSQL/Go
• Prototype user/authorization/nōtif management
• Linux/PostgreSQL/Python/Django
• Notifier SDK (Python)
• Sample “clockwatcher” notifier running
• Available on GitHub!
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27.
Under development
• Generate notifs from tweets
• IMAP gateway
• Connectors: Generate notifs from other
services
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28.
Backup Slides
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29.
Notification examples
• Emergency bulletins
• Advertising / special
offers
• Event invitations
• Approval requests
• Tech support
• Password resets
• Fraud alerts (bank, etc.)
• Alerts from
“things” (IoT)
• Newsletter availability
• Social media alerts
• Burglar/fire alarms
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30.
Nōtif characteristics
• Opt-in
• Typically short
• Modifiable/deletable (best effort)
• Acknowledged delivery
• Domain-signed
• Encrypted in transit (use TLS)
• Priority tagged
• Expires at specified date/time
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31.
Typical Nōtif
{"header": {"to": “d28363d7-9d28-49f2-8d5b-
b9c1cf989335@altmode.net:5342"},
"payload": “eyJhbGciOiAiUlMyNTYiLCAia2lkIjogInNoaW55In0.
eyJvcmlndGltZSI6ICIyMDE1LTA0LTA0VDE2OjE3OjAwLjI0MjE4MVoiLC
AicHJpb3JpdHkiOiA0LCAiZXhwaXJlcyI6ICIyMDE1LTA0LTA0VDE2OjE3
OjAwLjI0MjE5M1oiLCAiYm9keSI6ICJJdCBpcyBub3cgMDk6MTcgYW5kIG
FsbCBpcyB3ZWxsIiwgInN1YmplY3QiOiAiSXQgaXMgbm93IDA5OjE3In0.
MVXxsqrqc6XQm2gkVgatmHC847JEBxg0eR4LSmsUsTpMAwWgZ7dKQ_Wk_Q
K0It0aibj4qVdnJbs1MY6IwV7rqJMsSbzuZ7n_QDn_OKjI2L_rPq9IsW7z
EUtwf2T1J1j9yfWX0zmXwqSxdqnFHNcv49S7eDPrEhlvIMLtixHDOjk"}
Protected header
Unprotected header
Payload
Signature
Now in JWS format!
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32.
Protected Header
• Public key from DNS TXT record ala DKIM
• Algorithm must agree with that specified by key
record
{"alg": “RS256",
"kid": "shiny"}
Public key obtained from DNS:
<kid>._domainkey.<notifier-domain>
Signing and hashing algorithms
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33.
Nōtif Body
• You can’t spoof what isn’t there:
• From address/domain (comes from
authorization)
• To address (part of the envelope)
{"origtime": “2015-04-04T16:17:00.242181Z",
"priority": 4,
"expires": “2015-04-05T16:17:00.242193Z",
"body": "It is now 09:17 and all is well”,
"subject": "It is now 09:17"}
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