Adren Software

Disclaimer: All information on this page is not guaranteed to be correct or up to date. Everything is preliminary and is subject to change at any time.

Packet Structure

4B				4B				2B
YMSG				Version				pktlen
Service		Status				Session Id
DATA 0 - 65535

Currently the YMSG packet version is v18 (0x0012)

Verify - Service ID: 76 (0x4C)

Server returns a verify packet with a status of 1.
Status: 0
Session ID: 0
Parameters: None

Authentication - Service ID: 87 (0x57)

Status: 0 - Sent to the server
Session ID: 0
Parameters

• 1 : Username

Status: 1 - Sent from the server
The server will reply with a session id. Use this for any further packet sent to the server. Parameters

• 1 : Username
• 94 : Authentication Algorithm - Used in the hashing algorithm

Authentication Response - Service ID: 84 (0x54)

Status: 12 (0x0000000c) - Sent to the server
Parameters

• 1 : Username
• 0 : Username
• 277 : Authentication Token (v=1&n=7fkr3....; path=/; domain=.yahoo.com)
• 278 : Authentication Token 2 (z=90egLB....; path=/; domain=.yahoo.com)
• 307 : Authentication hash of crumb and challenge More Info
• 59 : B-Cookie
• 2 : Username
• 2 : "1" (Set this to the number 1 ASCII Value: 49)
• 244 : Client build number (16777151)
• 98 : 2 digit country code (us)
• 135 : Client version (11.0.0.1751)
• New Items added in 11.0.0.1751 -- Appear to be related to the multiple sign on system
• 300 : "508"
• 500 : Computer MAC Address
• 510 : "0"
• 301 : "508"

List - Service ID: 85 (0x55)

Contains information about the currently signed in user. (You)
Parameters

• 2 : Username
• 3 : Username
• 70 : Mobile Phone Number
• 89 : Username
• 216 : First Name
• 254 : Last Name
• 442 : Yahoo Power Users icon (See Status v15)

YMSG List v15 - Service ID: 241 (0xf1)

• 65 : Group Name
• 7 : Friend's Username
• 317 : Invisibility Status
  • 2 : means you show up as invisible to that person
• 223 : Add request pending
• 241 : 3rd Party Network (unconfirmed)
  • 2 : Windows Live

YMSG Status v15 - Service ID: 240 (0xf0)

• 10 : Availability
  • 0 : Available
  • 2 : Busy
  • 999 : Idle
• 241 : Possibly set if this is the first status update
• 192 : Photo Avatar Checksum
• 198 : Yahoo! Avatars Key
• 442 : Yahoo Power Users icon
  • 1 : Crown 1 -

YMSG SMS Message - Service ID: 746 (0x2ea)

• 4 : Cell Phone number
• 68 : Message Contents

YMSG Buddy Authentication - Service ID: 216 (0xd6)

Status: 3 - Buddy Requests

• 4 : Sender
• 14 : Request Message
• 216 : Sender's First Name
• 254 : Sender's Last Name

Status 0 - Buddy Response

• 1 : Username
• 5 : Buddy's Username
• 13 : Request Result
  • 1 : Accepted

Status 1 - 3rd Party Buddy Response

• 4 : Buddy's Username
• 5 : Username
• 13 : Request Result
  • 1 : Accepted

YMSG Add Buddy - Service ID: 131 (0x83)

• 1 : Username
• 7 : New buddy's username
• 65 : Group name to put the new buddy in
• 216 : First name to send to new buddy
• 254 : Last name to send to new buddy

YMSG Conference Invitation - Service ID: 24 (0x18)

• 50 : Sender
• 57 : Room Name
• 58 : Invitation Message

YMSG Mobile IM Setup - Service ID: 749 (0x2ed)

Received from the server after the user sets up mobile IM

• 4 : Unknown - Contents: "Yahoo Messenger"
• 5 : Username
• 70 : Phone number in format 15551234567

Computing the Auth Hash

X : Auth Crumb you get from https://login.yahoo.com/config/pwtoken_login...
Y : Challenge algorithm you get from the Authentication Packet (87) response (parameter 94)

1. MD5(X concat Y)
2. Base64 encode the MD5 hash
3. Replace the + sign with a .
4. Replace the / sign with a _
5. Replace the = sign with a -
6. Done