c-kzg-zig

Zig build packaging for c-kzg-4844.

This package exports:

• a c_kzg Zig module generated with translate-c from ckzg.h
• a blst Zig module generated with translate-c from the exact blst.h used to build c_kzg
• the c_kzg C library artifact
• the c-kzg public headers, installed on that artifact
• a trusted_setup Zig module with decoded byte slices for load_trusted_setup
• trusted_setup.txt as a named lazy path

This package does not export a handwritten Zig wrapper over the C API. It exports the translated C ABI directly, so consumers can import the module instead of writing their own @cImport.

Requirements

• Zig 0.16.0-dev

Public Surface

From a dependency handle:

• dep.module("c_kzg")
• dep.module("blst")
• dep.artifact("c_kzg")
• dep.module("trusted_setup")
• dep.namedLazyPath("trusted_setup")

The c_kzg artifact installs:

• the full c-kzg public header tree
• blst.h and related installed headers forwarded from blst.zig

The exported c_kzg module is produced by translate-c and links the packaged c_kzg library transitively. The exported blst module is produced from the same blst build step that c_kzg uses internally.

Ownership Model

This package owns the concrete blst version used to build c_kzg.

If downstream code needs only the KZG API, import c_kzg. If downstream code needs both the KZG API and direct blst access, import both c_kzg and blst from this package.

Do not add a second, separate blst.zig dependency next to c-kzg-zig unless you are intentionally taking ownership of the entire versioning and link-compatibility story yourself. Mixing two independently selected blst package instances is where symbol duplication and drift become possible.

Usage

Add dependencies to build.zig.zon:

.dependencies = .{
    .c_kzg = .{
        .url = "https://github.com/ChainSafe/c-kzg-zig/archive/refs/tags/v0.1.0.tar.gz",
        .hash = "<hash>",
    },
},

In build.zig:

const c_kzg_dep = b.dependency("c_kzg", .{
    .target = target,
    .optimize = optimize,
});

exe.root_module.addImport("c_kzg", c_kzg_dep.module("c_kzg"));
exe.root_module.addImport("blst", c_kzg_dep.module("blst"));
exe.root_module.addImport("trusted_setup", c_kzg_dep.module("trusted_setup"));

const install_setup = b.addInstallFile(
    c_kzg_dep.namedLazyPath("trusted_setup"),
    "trusted_setup.txt",
);
b.getInstallStep().dependOn(&install_setup.step);

In Zig code:

const c = @import("c_kzg");
const blst = @import("blst"); // Only if you need direct blst access.

The exported trusted_setup module contains the decoded buffers expected by load_trusted_setup:

const c = @import("c_kzg");
const trusted_setup = @import("trusted_setup");

var settings: c.KZGSettings = undefined;
try expectOk(c.load_trusted_setup(
    &settings,
    trusted_setup.g1_monomial_bytes.ptr,
    trusted_setup.g1_monomial_bytes.len,
    trusted_setup.g1_lagrange_bytes.ptr,
    trusted_setup.g1_lagrange_bytes.len,
    trusted_setup.g2_monomial_bytes.ptr,
    trusted_setup.g2_monomial_bytes.len,
    0,
));
defer c.free_trusted_setup(&settings);

If you want the original upstream text file at runtime instead, keep using dep.namedLazyPath("trusted_setup").

If you still want to use your own wrapper around the headers, dep.artifact("c_kzg") still installs the public header tree and can be linked directly.

Build Options

Option	Default	Description
-Dportable	false	Passed through to the package's build-time blst.zig dependency
-Dfield_elements_per_blob	4096	Override for non-mainnet

Tests

zig build test runs compile-time and C-API smoke tests against the exported embedded trusted setup module.

License

Apache 2.0.