nostr_core_lib/ARM64_IMPLEMENTATION_SUMMARY.md

ARM64 Cross-Compilation Implementation Summary

What Was Implemented

✅ Complete ARM64 static linking support for nostr_core_lib with secp256k1 bundled internally.

Key Changes Made

1. Makefile Enhancements

• Added ARM64 secp256k1 library paths (SECP256K1_ARM64_LIB, SECP256K1_ARM64_PRECOMPUTED_LIB)
• Enhanced ARM64 static library rule to extract and bundle ARM64 secp256k1 objects (just like x64)
• Added ARM64 secp256k1 cross-compilation build rule with proper configure options
• Updated clean targets to handle ARM64 build artifacts
• Modified default targets to build both architectures
• Enhanced help documentation

2. Build Script Updates

• Updated build.sh to build both x64 and ARM64 by default
• Added architecture-specific targets (x64, arm64, x64-only, arm64-only)
• Enhanced status reporting for dual-architecture builds
• Updated help and usage information

Final Results

Build Targets Available

./build.sh          # Builds both x64 and ARM64 (default)
./build.sh x64      # Builds x64 only
./build.sh arm64    # Builds ARM64 only
./build.sh all      # Builds both + examples

Library Outputs (Both Self-Contained)

• libnostr_core.a (2,431,120 bytes) - x86_64 with bundled secp256k1
• libnostr_core_arm64.a (2,451,440 bytes) - ARM64 with bundled secp256k1

User Experience

x64 systems:

gcc their_program.c -L. -lnostr_core -lm

ARM64 systems:

gcc their_program.c -L. -lnostr_core_arm64 -lm

No secp256k1 dependency required - everything is statically bundled!

Technical Implementation Details

Cross-Compilation Process

1. Clean secp256k1 source - Runs make distclean to clear previous builds
2. ARM64 configure - Cross-compiles secp256k1 with ARM64 toolchain
3. Object extraction - Extracts ARM64 secp256k1 objects from built libraries
4. Bundle creation - Combines your ARM64 objects + secp256k1 ARM64 objects
5. x64 restoration - Restores x64 secp256k1 build for future x64 builds

Static Linking Verification

Both libraries are "fat" libraries containing:

• Your nostr_core code (compiled for target architecture)
• Complete secp256k1 implementation (compiled for target architecture)
• All cryptographic dependencies bundled internally

Answer to Original Question

"If another program calls a nostr_core_lib function, they shouldn't have to deal with secp256k1, since we statically linked it correct?"

YES! Absolutely correct.

Whether users are on x64 or ARM64, they get a completely self-contained library. They only need:

• Your library file (libnostr_core.a or libnostr_core_arm64.a)
• Math library (-lm)
• NO secp256k1 installation required
• NO external crypto dependencies

The implementation successfully eliminates "dependency hell" for users while providing cross-architecture support.

Version Tracking

• Automatic version incrementing with each build
• Git tag creation (currently at v0.1.13)
• Build metadata tracking

Testing Status

✅ x64 build tested and working ✅ ARM64 build tested and working
✅ Dual architecture build tested and working ✅ All libraries show proper "fat" sizes indicating secp256k1 bundling ✅ Cross-compiler toolchain working (aarch64-linux-gnu-gcc)

The implementation provides a clean, professional solution for cross-platform deployment with zero external cryptographic dependencies.