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

====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.