leeqwind / fuzzy-wasm

ssdeep demonstration library for WebAssembly

fuzzy-wasm: ssdeep demonstration library for WebAssembly

This library is intended for demo of fuzzy hashing on web browser which runs WebAssembly. It has slight modifications from the original ssdeep (version 2.14):

• Built-in libc functions
• Minimum dependencies to libc to minimize wasm file size
• Stateful APIs for zero dynamic memory allocation
• Some variables made global (because it cannot access local variables through pointers)

Build Requirements

• LLVM and Clang 5.0 or later (with WebAssembly experimental backend)

API Differences

• fuzzy_new does not return context and other APIs don't have struct fuzzy_state* typed argument.
• fuzzy_set_total_input_length have two length arguments (high half and low half) because we cannot provide 64-bit integer arguments from JavaScript.
• Temporary buffer intended for digests are pre-allocated. Its address can be retrieved from fuzzy_wasm_get_temp_buffer and slot count and size per slot can be retrieved from fuzzy_wasm_get_temp_buffer_count and fuzzy_wasm_get_temp_buffer_slot_size functions. Note that the size per slot is barely enough for digests with no file names. So, you need to care about buffer size.

Files (including generated ones)

• fuzzy-wasm.c, sum_table.h
  Slightly modified ssdeep 2.14 source code
• musl-libc.h
  Part of musl libc https://www.musl-libc.org/
• fuzzy-wasm.wast
  WebAssembly AST
• fuzzy-wasm.wasm
  WebAssembly module (in binary format)