d2r_offline 1.0

d2r_offline is a compact C++ project for reproducing the offline startup/session flow of Diablo II: Resurrected without the Blizzard launcher through a proxy winhttp.dll.

The project does the following:

• replaces winhttp.dll while forwarding the original WinHTTP exports to the real system library
• publishes the expected environment and registry responses
• patches the trusted PUBLIC KEY in the Diablo II: Resurrected process memory
• generates a compatible %LocalAppData%\Blizzard Entertainment\ClientSdk\cookie.bin

Structure

• src/config — config loading and locale normalization
• src/crypto — Windows CNG/CryptoAPI backend and Serpent CTR
• src/cookie — claims, machine context, cryptobox, and cookie.bin writing
• src/exports — export list and asm forwarders
• src/proxy — process bootstrap and WinHTTP forwarder loading
• src/runtime — runtime patches and registry hook implementation
• src/support — shared types, key material, logging, and platform helpers

Build

Requirements:

• Windows x64
• Visual Studio 2022 Build Tools

Build:

powershell -ExecutionPolicy Bypass -File .\build.ps1

Output:

• build\winhttp.dll

Usage

To use the proxy with Diablo II: Resurrected:

1. Either build the project and take build\winhttp.dll, or download winhttp.dll from the project release.
2. Copy winhttp.dll into the game directory, next to the main game executable.
3. Start the game executable directly, without the Blizzard launcher.
4. On first launch, let the DLL generate d2r_offline.ini automatically or place your own config next to winhttp.dll.
5. After a successful start, the offline cookie will be written to %LocalAppData%\Blizzard Entertainment\ClientSdk\cookie.bin.

Recommended first-run checks:

• d2r_offline.log is created next to winhttp.dll
• cookie.bin is created under %LocalAppData%\Blizzard Entertainment\ClientSdk\
• the game starts with the expected language and offline session state

Config

The DLL looks for d2r_offline.ini next to itself. If the file does not exist, it is created automatically:

[Settings]
Locale=english
LocaleAudio=english
Entitlements=hd,beta,rotw-dlc

Supported keys:

• Locale
• LocaleAudio
• Entitlements

Supported Locale and LocaleAudio values:

• english -> enUS
• german -> deDE
• spanish -> esES
• latam -> esMX
• french -> frFR
• italian -> itIT
• koreana / korean -> koKR
• polish -> plPL
• brazilian -> ptBR
• portuguese -> ptPT
• russian -> ruRU
• tchinese -> zhTW
• schinese -> zhCN
• japanese -> jaJP

You can also provide a Blizzard locale code directly, for example enUS or ruRU.

The runtime log is written to d2r_offline.log next to the DLL and is recreated on every launch.

Notes

• the output file remains winhttp.dll because the client loads that exact module name
• the implementation targets practical compatibility, not binary identity
• the crypto layer uses Windows CNG/CryptoAPI and vendored Serpent