garble

GO111MODULE=on go get mvdan.cc/garble

Obfuscate a Go build. Requires Go 1.13 or later.

garble build [build flags] [packages]

which is equivalent to the longer:

GARBLE_DIR="$PWD" go build -a -trimpath -toolexec=garble [build flags] [packages]

Purpose

Produce a binary that works as well as a regular build, but that has as little information about the original source code as possible.

The tool is designed to be:

• Coupled with cmd/go, to support both GOPATH and modules with ease
• Deterministic and reproducible, given the same initial source code
• Reversible given the original source, to un-garble panic stack traces

Mechanism

The tool wraps calls to the Go compiler to transform the Go source code, in order to:

• Replace as many useful identifiers as possible with short base64 hashes
• Remove module build information
• Strip filenames and unnecessary lines, to make position info less useful

It also wraps calls to the linker in order to:

• Enforce the -s flag, to not include the symbol table
• Enforce the -w flag, to not include DWARF debugging data

Finally, the tool requires the use of the -trimpath build flag, to ensure the binary doesn't include paths from the current filesystem.

Caveats

• The -a flag for go build is required, since -toolexec doesn't work well with the build cache; see #27628.

• Since no caching at all can take place right now (see the link above), builds will be slower than go build - especially for large projects.

• The standard library is never garbled when compiled, since the source is always publicly available.

• Deciding what method names to garble is always going to be difficult, due to interfaces that could be implemented up or down the package import tree.

• Similarly to methods, exported struct fields are difficult to garble, as the names might be relevant for reflection work like encoding/json