strip-nondeterminism

Strip nondeterministic information from a file

$ strip-nondeterminism [path/to/file]

$ strip-nondeterminism --type [filetype] [path/to/file]

$ strip-nondeterminism --timestamp [unix_timestamp] [path/to/file]

strip-nondeterminism [options] file...

--help
    Display help message and exit.

--version
    Display version information and exit.

The `strip-nondeterminism` command is a utility designed to remove sources of non-determinism from object files, executables, and archive files. Non-determinism in these files can arise from various factors, such as timestamps, build paths, and other data that changes between compilations, even if the source code remains identical. By removing these elements, `strip-nondeterminism` helps ensure that builds are reproducible, meaning that compiling the same source code multiple times will produce identical output files. This is crucial for build systems that rely on bit-for-bit comparisons to detect changes or to verify the integrity of software. It supports various object file formats like ELF, PE and Mach-O, and archive formats like `ar` archives. This tool is crucial for creating reliable and verifiable software builds, which is especially important for security and auditing purposes. Using `strip-nondeterminism` typically involves specifying the file(s) to be processed, and it attempts to remove non-deterministic elements such as build paths or timestamps. The goal is to produce an output file that is identical across different build environments and times, given the same source code.

This tool may not be able to remove all sources of non-determinism, especially in cases where non-deterministic data is deeply embedded within the file format or generated dynamically during the build process. Its effectiveness depends on the specific build system and the types of non-deterministic data present in the input files.

Under the hood, the command typically parses the object file or executable format, identifies sections containing non-deterministic information (e.g., debug sections with timestamps), and replaces or removes that data. The exact methods used depend on the file format. For example, it might zero out timestamps or replace build paths with a standardized value.

Note: This tool may overwrite the input file or create a modified version, depending on its configuration or implementation.

Achieving fully reproducible builds often requires a combination of tools and techniques, including `strip-nondeterminism`, controlled build environments (e.g., containers), and careful management of dependencies. `strip-nondeterminism` plays a vital role in removing variable components from the final binary, but it must be used in conjunction with other reproducible build practices to achieve complete reproducibility. Reproducible builds are important for security because they allow end-users to verify independently that the binaries they are running were built from the claimed source code and that no malicious modifications were introduced during the build process.

The `strip-nondeterminism` command has emerged as a critical component in the ongoing effort to improve software build reproducibility. Its development stems from the need to create build environments where identical source code produces identical binary outputs, irrespective of the build machine or time. Originally incorporated into build systems for specific software packages, its utility has led to its adoption as a standalone tool in recent years. Its usage has grown alongside the increasing emphasis on software supply chain security and verifiable builds.

strip(1), objcopy(1), ld(1)