====== 1. Preparation ======

Before you can compile OpenSSL, some tools need to be installed.

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===== What do I need? =====

^ Tool ^ For what? ^ Required? ^
| Visual Studio 2022 | C/C++ Compiler | **Yes** |
| Strawberry Perl | Configuration scripts | **Yes** |
| NASM | Assembly optimizations | Recommended |
| Git | Download source code | **Yes** |
| Windows SDK | Header files | **Yes** (usually included with VS) |

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===== Quick Installation =====

<WRAP tip>
**For the impatient:** These three commands install everything you need:
</WRAP>

<code powershell>
# Visual Studio 2022 Community (free)
winget install Microsoft.VisualStudio.2022.Community

# Perl for build scripts
winget install StrawberryPerl.StrawberryPerl

# NASM for faster cryptography
winget install NASM.NASM
</code>

<WRAP important>
After installation: **Restart computer** so all paths are set!
</WRAP>

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===== Detailed Guides =====

  * [[.:windows-tools|Install Windows Tools]] - Step by step
  * [[.:wsl-einrichten|Set up WSL2]] - For Linux builds on Windows
  * [[.:emscripten|Emscripten SDK]] - For WASM/Blazor builds

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===== Verification =====

After installation you can check if everything works:

<code powershell>
# 1. Load Visual Studio environment
& "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"

# 2. Check C compiler
cl
# Expected output: Microsoft (R) C/C++ Optimizing Compiler Version 19.xx

# 3. Check Perl
perl -v
# Expected output: This is perl 5, version xx

# 4. Check NASM (optional)
nasm -v
# Expected output: NASM version 2.xx
</code>

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===== Frequently Asked Questions =====

**Q: Do I need Visual Studio Professional/Enterprise?**

No! Visual Studio **Community** is free and sufficient.

**Q: Can I use a different C compiler?**

Theoretically yes (MinGW, Clang), but the Microsoft compiler is best tested for Windows.

**Q: What is NASM and do I really need it?**

NASM is an assembler. OpenSSL has hand-optimized assembly routines for AES, SHA, etc. Without NASM, slower C implementations are used. For production builds: **Install NASM!**

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===== Continue to =====

  * [[.:windows-tools|Install Windows Tools in Detail]]
  * [[.:quellen:start|2. Download Sources]]

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//Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional//