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Firefox OS/Remote Control (view source)

Revision as of 03:39, 24 May 2016

319 bytes added ,  24 May 2016
→‎Architecture Designs: add disconnect and reconnection description
(→‎Request handshake: Put id to detail)
(→‎Architecture Designs: add disconnect and reconnection description)
 
(6 intermediate revisions by the same user not shown)
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# Peer authentication
# Peer authentication
# Control event processing
# Control event processing
Any error occurs will close connection between server and client, reconnection is required. Server side error will sends message back to client to let user know what happen on Fennec.


=== Peer authentication ===
=== Peer authentication ===
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# Client computes J-PAKE round 1 and sends the result to server.
# Client computes J-PAKE round 1 and sends the result to server.
# Server generates PIN code and show on screen, computes J-PAKE round 1 and sends the result to client.
# Server generates PIN code and show on screen, computes J-PAKE round 1 and sends the result to client.
# Server computes J-PAKE round 2 with PIN code attached first 12 characters of server's TLS certificate fingerprint as weak secret.
# User enter PIN code, client computs J-PAKE round 2 with PIN code attached first 12 characters of server's TLS certificate fingerprint as weak secret.
# User enter PIN code, client computs J-PAKE round 2 with PIN code attached first 12 characters of server's TLS certificate fingerprint as weak secret.
# Client sends round 2 result to server.
# Client sends round 2 result to server.
# Server computes J-PAKE round 2 with PIN code attached first 12 characters of server's TLS certificate fingerprint as weak secret.
# Server dismisses PIN code notification on screen, sends round 2 result to client.
# Server dismisses PIN code notification on screen, sends round 2 result to client.
# Both client and server compute J-PAKE final round, gets AES and HMAC key.
# Both client and server compute J-PAKE final round, gets AES and HMAC key.
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# Client computes J-PAKE round 1 and sends the result to server.
# Client computes J-PAKE round 1 and sends the result to server.
# Server computes J-PAKE round 1 and sends the result to client.
# Server computes J-PAKE round 1 and sends the result to client.
# Client and server computes J-PAKE round 2 with previous AES key value attached first 12 characters of server's TLS certificate fingerprint as weak secret.
# Client and server computes J-PAKE round 2 with first 4 characters of previous AES key value attached first 12 characters of server's TLS certificate fingerprint as weak secret.
# Client sends round 2 result to server.
# Client sends round 2 result to server.
# Server sends round 2 result to client.
# Server sends round 2 result to client.
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# Client.sjs parses event and dispatch to Gecko or Gaia system app.
# Client.sjs parses event and dispatch to Gecko or Gaia system app.


=== Data encryption/decryption ===
=== Data used in JPAKE authentication ===
There are three kinds of data are encrypted while tranmission:
==== Singer ID for JPAKE round 1 & 2: ====
# Client polls '''UUID''' in establish secure connection stage
* TV: server
# Client sends '''PIN code''' in pin code pairing
* Fennec addon: client
# Client sends '''event''' in control event processing
 
==== Weak secret: ====
* TV: concatenate PIN and first 12 characters of TLS server cert SHA 256 fingerprint
* Fennec addon: concatenate user input PIN and first 12 characters connected TLS server cert SHA 256 fingerprint
 
==== HMAC Input for JAPKE final: ====
We use "AES_256_CBC-HMAC256", as aHkdfInfo, includes the full crypto spec, should be the same in both TV and fennec addon
 
==== Key confirmation: ====


As data are encrypted by symmetric key, AES-GCM, there are two things need noticed:
Double hash of AES key:
# AES-GCM need initialization vector(IV) to encrypt/decrypt. Currently, IV is random value for each data, length is 12 bytes. Encrypted data is appended after IV. Receiver needs to slice first 12 bytes as IV to decrypt.
## TV converts AES key to array buffer
# Each message type is string, use [https://developer.mozilla.org/en-US/docs/Web/API/TextEncoder/encode TextEncoder.encode()] to encode as an UInt8Array, then encrypt to ArrayBuffer. Vice versa.
## Sign AES key array buffer, get signature 1 (array buffer)
# Data encryption/decryption is asynchronous but HTTP request need response immediately. For UUID and PIN code case, remote control uses a ticket number to get status after decryption. But for event, we reduce polling result but use latest event's result instead.
## Sign signature 1, get signature 2
## Convert signature 2 to base 64, send to Fennec addon
## Fennec addon do the same as TV from step 1 to 4
## Compare received base 64 string of self and TV's signature 2
 
Single hash of AES key:
## Fennec addon converts AES key to array buffer
## Sign AES key array buffer, get signature 1 (array buffer)
## Convert signature 1 to base 64, send to TV
## TV use HMAC key, received signature, AES key array buffer to verify if the signature is valid.


=== Authentication and Event Protocol ===
=== Authentication and Event Protocol ===
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       gx1: gx1.value,
       gx1: gx1.value,
       gx2: gx2.value,
       gx2: gx2.value,
       zpk_x1: { gr: gv1.value, b: r1.value, id: 'client' },
       zkp_x1: { gr: gv1.value, b: r1.value, id: 'client' },
       zpk_x2: { gr: gv2.value, b: r2.value, id: 'client' }
       zkp_x2: { gr: gv2.value, b: r2.value, id: 'client' }
     }
     }
   }
   }
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       gx1: gx1.value,
       gx1: gx1.value,
       gx2: gx2.value,
       gx2: gx2.value,
       zpk_x1: { gr: gv1.value, b: r1.value, id: 'server' },
       zkp_x1: { gr: gv1.value, b: r1.value, id: 'server' },
       zpk_x2: { gr: gv2.value, b: r2.value, id: 'server' }
       zkp_x2: { gr: gv2.value, b: r2.value, id: 'server' }
     }
     }
   }
   }
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   }
   }


==== Custom Events ====
==== Server reply error ====


   {
   {
     type: 'command'
     type: common, or the event type sent from client
    action: 'custom',
     error: <error message of exception or root cause>
     detail: {
      action: <custom action name, string>,
      ...
    }
   }
   }


Eric Tsai
133

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