This directory holds build scripts for unofficial, unsupported distributions of Go+BoringCrypto.

Version strings

The distribution name for a Go+BoringCrypto release has the form <GoVersion>b<BoringCryptoVersion>, where <GoVersion> is the Go version the release is based on, and <BoringCryptoVersion> is an integer that increments each time there is a new release with different BoringCrypto bits. The <BoringCryptoVersion> is stored in the VERSION file in this directory.

For example, the first release is based on Go 1.8.3 is go1.8.3b1. If the BoringCrypto bits are updated, the next would be go1.8.3b2. If, after that, Go 1.9 is released and the same BoringCrypto code added to it, that would result in go1.9b2. There would likely not be a go1.9b1, since that would indicate Go 1.9 with the older BoringCrypto code.


The build.release script prepares a binary release and publishes it in Google Cloud Storage at gs://go-boringcrypto/, making it available for download at<FILE>. The script records each published release in the RELEASES file in this directory.

The build.docker script, which must be run after build.release, prepares a Docker image and publishes it on Google Artifact Registry. go1.17.2b7 is published as

Release process

Development is done on the dev.boringcrypto branch, which tracks master. Releases are cut from dev.boringcrypto.go1.X branches, which are BoringCrypto backported to the Go 1.X release branches. To issue new BoringCrypto releases based on Go 1.X:

  1. If the BoringCrypto bits have been updated, increment the number in VERSION, send that change out as a CL for review, get it committed to dev.boringcrypto, and run git sync.

  2. Change to the dev.boringcrypto.go1.X branch and cherry-pick all BoringCrypto updates, including the update of the VERSION file. If desired, merge release-branch.go1.X into dev.boringcrypto.go1.X. Mail them out and get them committed.

  3. Back on the dev.boringcrypto branch, run git fetch, make.bash and then build.release dev.boringcrypto.go1.X. The script will determine the base Go version and the BoringCrypto version, build a release, and upload it.

  4. Run build.docker, which will build and upload a Docker image from the latest release.

  5. Send out a CL with the updated RELEASES file and get it committed to dev.boringcrypto.

Building from Docker

A Dockerfile that starts with FROM golang:1.17.2 can switch to FROM and should need no other modifications.

Building from Bazel

Starting from bazelbuild/rules_go tag 0.7.1, simply download the BoringCrypto-enabled Go SDK using go_download_sdk() before calling go_register_toolchains().

For example, to use Go 1.9.3 with BoringCrypto on Linux, use the following lines in WORKSPACE:

load("@io_bazel_rules_go//go:def.bzl", "go_rules_dependencies", "go_download_sdk", "go_register_toolchains")


    name = "go_sdk",
    sdks = {
       "linux_amd64": ("go1.9.3b4.linux-amd64.tar.gz", "db1997b2454a2f27669b849d2d2cafb247a55128d53da678f06cb409310d6660"),
    urls = ["{}"],


Note: you must not enable pure mode, since cgo must be enabled. To ensure that binaries are linked with BoringCrypto, you can set pure = "off" on all relevant go_binary rules.


BoringCrypto is used for a given build only in limited circumstances:

  • The build must be GOOS=linux, GOARCH=amd64.
  • The build must have cgo enabled.
  • The android build tag must not be specified.
  • The cmd_go_bootstrap build tag must not be specified.

The version string reported by runtime.Version does not indicate that BoringCrypto was actually used for the build. For example, linux/386 and non-cgo linux/amd64 binaries will report a version of go1.8.3b2 but not be using BoringCrypto.

To check whether a given binary is using BoringCrypto, run go tool nm on it and check that it has symbols named *_Cfunc__goboringcrypto_*.

The program will report the crypto implementation used by a given binary when invoked with the -crypto flag.