Editing WoW:Battle.net Mobile Authenticator Specification (section)

==Server Communication==

===Authenticator Initialization===

====Authenticator Initialization Request====
Initialization request is an HTTP POST request to
* ''<nowiki>http://m.eu.mobileservice.blizzard.com/enrollment/enroll.htm</nowiki>'' (Europe) (old)
* ''<nowiki>http://m.us.mobileservice.blizzard.com/enrollment/enroll.htm</nowiki>'' (North America) (old)
* ''<nowiki>http://mobile-service.blizzard.com/enrollment/enroll.htm</nowiki>'' (new)
with Content-type "application/octet-stream".


The plaintext of the request has the following format:
{| class="darktable"
|-
! style="width:15%;" align="left" | function code
! style="width:40%;" align="left" | response encryption key
! style="width:15%;" align="left" | region code
! style="width:30%;" align="left" | mobile model
|-
| 1 byte
| 37 bytes
| 2 bytes
| 16 bytes
|}
;Function code
: always 0x01
;Response encryption key
: Random bytes for one time pad encryption of the response. Blizzard is using the default Java random number generator (initialized with the current system time), hashes the created random bytes via SHA1 and is using the hash output for the key. But every other good source of randomness would be also OK here.
;Region code
: "EU" or "US" but doesn't have any meaning - distinction is only done via the URL and not via the code here.
;Mobile model
: Default value is "Motorola RAZR v3" but every other 16 bytes would be also OK. Seems to be only a statistical record.


The plaintext is then encrypted with RSA-1024 (upper bytes of the RSA-block are padded with zeros). The modulus is
 0x955e4bd989f3917d2f15544a7e0504eb9d7bb66b6f8a2fe470e453c779200e5e
   3ad2e43a02d06c4adbd8d328f1a426b83658e88bfd949b2af4eaf30054673a14
   19a250fa4cc1278d12855b5b25818d162c6e6ee2ab4a350d401d78f6ddb99711
   e72626b48bd8b5b0b7f3acf9ea3c9e0005fee59e19136cdb7c83f2ab8b0a2a99
(big endian) and the public exponent is "0x101" (257). The resulting 128 encrypted bytes are sent to the server within the HTTP-POST-request. Europe and North America are using the same keys for RSA.


====Authenticator Initialization Response====
The HTTP body of the response has the following format:
{| class="darktable"
|-
! style="width:40%;" align="left" | current server time
! style="width:60%;" align="left" | encrypted initialization data
|-
| 8 bytes
| 37 bytes
|}
;Current server time
: Milliseconds since midnight, January 1, 1970 UTC (like returnded by System.currentTimeMillis() in Java), big endian format.
;Encrypted initialization data
: One time pad encrypted data with initialization information for the authenticator. The decryption key is the key sent to the server within the initialization request.


After decryption the initialization information has the following format:
{| class="darktable"
|-
! style="width:60%;" align="left" | secret key for code calculation
! style="width:40%;" align="left" | authenticator serial number
|-
| 20 bytes
| 17 bytes
|}
;Secret key for code calculation
: Secret key generated by the server for calculation of the authenticator codes. Refer to [[#Code Calculation|code calculation section]] for the usage of this key. The key ''MUST'' be stored within the authenticator as long as it is linked to a Battle.net account and ''MUST'' kept secret.
;Authenticator serial number
: Serial number of the authenticator used for linking it to a Battle.net account. It has the format "EU-1234-5678-9012" or "US-1234-5678-9012". The number seems to be simply incremented by the server for every initialization request. There should be no way to calculate the secret key corresponding to this serial number. The serial number ''SHOULD'' be stored together with the secret key. Though it isn't any longer possible to link a single authenticator to more than one Battle.net account at a time<ref>Blizzard Entertainment: Battle.net Blog: [http://us.battle.net/sc2/en/blog/882513 Battle.net Authenticator Change] (Oct 7, 2010)</ref>, but maybe the support will ask for the serial number if there is a problem with the authenticator.


===Authenticator Time Synchronization===

====Authenticator Time Synchronization Request====
Synchronization request is simply an HTTP GET request to
:* ''<nowiki>http://m.eu.mobileservice.blizzard.com/enrollment/time.htm</nowiki>'' (Europe) (old)
:* ''<nowiki>http://m.us.mobileservice.blizzard.com/enrollment/time.htm</nowiki>'' (North America) (old)
:* ''<nowiki>http://mobile-service.blizzard.com/enrollment/time.htm</nowiki>'' (new)


====Authenticator Time Synchronization Response====
The HTTP body of the response has the following format:
{| class="darktable"
|-
! align="left" | current server time
|-
| 8 bytes
|}
;Current server time
: Milliseconds since midnight, January 1, 1970 UTC (like returned by System.currentTimeMillis() in Java), big endian format.