# Table of contents:

• Introduction
• Client/Request
  • Challenge responses
    • Basic responses
    • Advanced responses
• Server/Response
• Examples
  • Successful response
  • Failed challenge
• Known changes

# Introduction

QRY is a command introduced with MSNP6.

It is a Notification Server command, WITH a request payload but without a response payload.

Responds to a challenge request (CHL command).

# Client/Request

QRY TrID public-key length
payload

Where public-key is your client's Public Key. For a list of valid Public Keys, read the Challenge Key Pairs article.

Where length is the size (in bytes) of the payload.

Where payload is the challenge response.

# Challenge responses

Calculating the challenge response depends on the version of the protocol you are using.

For a list of valid Private Keys, read the Challenge Key Pairs article.

# Basic responses

Only in MSNP6 to MSNP10.

Simply MD5 hash the challenge and your client's Private Key concatenated together as a string.

For an implementation of this, review SolveMSNP6Challenge in msnp_challenges.cs.

The output should be 32 bytes and lowercase hexadecimal.

# Advanced responses

Since MSNP11.

1. MD5 hash the challenge and your client's Private Key concatenated together as a string.
2. Create an 32-bit integer array with the size of 4, with the contents being each part of the first step put through a bitwise AND of 0x7FFFFFFF.
3. Concatenate the challenge and Public Key together and save as a new string.
4. Pad the string to the right if it's length can not be divided by 8.
5. Create a new 32-bit integer array with the size of the padded string's length divided by 4, with the contents being 4 bytes of the fourth step put through a bitwise AND of 0x7FFFFFFF.
6. Initialize three 64-bit variables, one called temp, another called high, and the last called low.
7. In a loop, iterate the array made in step 5, and increase the iterator by 2 every pass.
   1. The temp variable should be set to the part of the array created in the fifth step indexed by the iterator.
   2. Multiply and set temp by 0x0E79A9C1.
   3. Modulo (not bitwise AND) and set temp by 0x7FFFFFFF.
   4. Add and set temp by the contents of high.
   5. Multiply and set temp by the first part of the array made in step 2.
   6. Add the value of the second part of the array made in step 2 to temp.
   7. Modulo and set temp by 0x7FFFFFFF.
   8. Set high to the part of the array created in the fifth step indexed by the iterator plus 1.
   9. Add and set high to the value of temp.
   10. Modulo high by 0x7FFFFFFF.
   11. Multiply and set high by the third part of the array made in step 2.
   12. Add and set high by the value of the fourth part of the array made in step 2.
   13. Modulo and set high by 0x7FFFFFFF.
   14. Add and set low to the result of high and temp being added together.
8. We have now finished the loop.
9. Add and set high by the value of the second part of the array made in step 2.
10. Modulo high by 0x7FFFFFFF.
11. Swap the endianness of the 32-bit segment of high.
12. Add and set low by the value of the fourth part of the array made in step 2.
13. Modulo low by 0x7FFFFFFF.
14. Swap the endianness of the 32-bit segment of low.
15. Create a new 64-bit variable named key.
16. Set the value of key to the value of high shifted 32 bits to the left, and the value of low.
17. Swap the endianness of the entire 64-bit segment of key.
18. Create two new 64-bit variables, one resultHigh, and the other resultLow.
19. Set resultHigh to the first 64 bits of the value created in step 1.
20. Set resultLow to the last 64 bits of the value created in step 1.
21. Bitwise XOR and set resultHigh by the value of key.
22. Bitwise XOR and set resultLow by the value of key.
23. Concatenate the values of resultHigh and resultLow as a set of bytes.
24. Convert the concatenated values into a hex stream.

For an implementation of this, review SolveMSNP11Challenge in msnp_challenges.cs.

The output should be 32 bytes and lowercase hexadecimal.

# Server/Response

QRY TrID

# Examples

# Successful response

S: CHL 12345678901234567890
C: QRY 1 msmsgs@msnmsgr.com 32
8ba1bb9d6dbf624fee31a2053af5fdd0
S: QRY 1

# Failed challenge

NOTE: This happens as-is in MSNP11, since it isn't using the new method.

S: CHL 12345678901234567890
C: QRY 2 msmsgs@msnmsgr.com 32
8ba1bb9d6dbf624fee31a2053af5fdd0
S: 540 2

Server disconnects client.

# Known changes

• MSNP11: Changed challenge response generation algorithm drastically.