KZG-WASM

This module implements a JS wrapper around a WASM compilation of the c-kzg-4844 C library built for use with EIP-4844. Starting with v1.0.0, the library also support cell-based operations in the context of EIP-7594 (PeerDAS).

This library is produced by building the original C code to WASM using the empscripten toolchain in this fork of c-kzg-4844.

Usage

This module exposes a single export, an async function called loadKZG which loads and compiles the WASM object, loads a trusted setup (defaults to the official setup from the KZG ceremony) and returns an object that exposes the API defined in the KZG type interface in @ethereumjs/util

To use with the @ethereumjs libraries, do the following:

``ts
import { loadKZG } from 'kzg-wasm'
import { Common, Chain, Hardfork } from '@ethereumjs/common'

const main = async () => {
const kzg = await loadKZG()
const common = new Common({
chain: Chain.Mainnet,
hardfork: Hardfork.Cancun,
customCrypto: { kzg },
})
console.log(common.customCrypto.kzg) // Should print the initialized KZG interface
}

main()
`

API Reference

The loadKZG() function returns an object that implements the KZG interface with the following methods:

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#### loadTrustedSetup(trustedSetup?, precompute?)
`ts
loadTrustedSetup(trustedSetup: TrustedSetup = mainnetTrustedSetup, precompute: number = 0): number
`
Loads a trusted setup for KZG operations. Returns 0 on success, non-zero on failure.

#### freeTrustedSetup()
`ts
freeTrustedSetup(): void
`
Frees the loaded trusted setup from memory.

#### blobToKZGCommitment(blob)
`ts
blobToKZGCommitment(blob: string): string
`
Converts a blob of data into a KZG commitment. Takes a prefixed hex string containing 4096 big endian KZG field elements and returns a 48-byte KZG commitment as a prefixed hex string.

#### computeBlobKZGProof(blob, commitment)
`ts
computeBlobKZGProof(blob: string, commitment: string): string
`
Computes a KZG proof for a blob and its commitment. Returns a 48-byte KZG proof as a prefixed hex string.

#### verifyBlobKZGProof(blob, commitment, proof)
`ts
verifyBlobKZGProof(blob: string, commitment: string, proof: string): boolean
`
Verifies a KZG proof against a blob and its commitment. Returns true if the proof is valid, false otherwise.

#### verifyBlobKZGProofBatch(blobs, commitments, proofs)
`ts
verifyBlobKZGProofBatch(blobs: string[], commitments: string[], proofs: string[]): boolean
`
Verifies multiple KZG proofs in batch. All arrays must have the same length. Returns true if all proofs are valid, false otherwise.

#### verifyKZGProof(commitment, z, y, proof)
`ts
verifyKZGProof(commitment: string, z: string, y: string, proof: string): boolean
`
Verifies a KZG proof for specific points z and y against a commitment. Returns true if the proof is valid, false otherwise.

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#### computeCellsAndKZGProofs(blob)
`ts
computeCellsAndKZGProofs(blob: string): KZGProofWithCells
`
Computes all 128 cells and their corresponding KZG proofs for a blob. Returns an object containing arrays of proofs and cells.

#### recoverCellsFromKZGProofs(cellIndices, partialCells, numCells)
`ts
recoverCellsFromKZGProofs(cellIndices: number[], partialCells: string[], numCells: number): KZGProofWithCells
`
Recovers all cells and proofs from partial cell data. Requires at least 50% of the total cells to be provided. Returns the complete set of proofs and cells.

#### verifyCellKZGProof(commitment, cells, proofs)
`ts
verifyCellKZGProof(commitment: string, cells: string[], proofs: string[]): boolean
`
Verifies KZG proofs for specific cells against a commitment. Returns true if all proofs are valid, false otherwise.

#### verifyCellKZGProofBatch(commitments, cellIndices, cells, proofs, numCells)
`ts
verifyCellKZGProofBatch(commitments: string[], cellIndices: number[], cells: string[], proofs: string[], numCells: number): boolean
`
Verifies multiple cell KZG proofs in batch. All arrays must have the same length and match numCells. Returns true if all proofs are valid, false otherwise.

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The library also provides aliases for compatibility with different naming conventions:

- blobToKzgCommitment - alias for blobToKZGCommitment
- computeBlobProof - alias for computeBlobKZGProof

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#### TrustedSetup
`ts
type TrustedSetup = {
g1_monomial: string
g1_lagrange: string
g2_monomial: string
}
`

#### KZGProofWithCells
`ts
type KZGProofWithCells = {
proofs: string[] // Array of 128 proofs, each 48 bytes
cells: string[] // Array of 128 cells, each 2048 bytes
}
`

Development

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This section outlines the build scripts included in this repository to create distributable JavaScript/TypeScript packages from the WASM compilation.

#### Prerequisites

Ensure you have the following installed:
- Node.js (v16+)
- npm
- TypeScript (installed as dev dependency)
- Babel (installed as dev dependency)

#### Build Scripts Overview

The repository includes the following build scripts:

1. build - Main build command
2. build:ts - TypeScript compilation to multiple targets
3. transpileCJS - Babel transpilation for CommonJS compatibility
4. fixRequire - Fix dynamic require statements
5. fixWasmDirInNode - Fix WASM paths for Node.js builds
6. fixWasmDirInWeb - Fix WASM paths for browser builds

#### Script Details

build:ts (scripts/ts-build.sh)
- Copies WASM file to dist/wasm/
- Compiles TypeScript to CommonJS (dist/cjs/)
- Compiles TypeScript to ESM (dist/esm/)
- Creates browser build (dist/browser/)

transpileCJS
- Uses Babel to transpile src/kzg.js to dist/cjs/
- Ensures CommonJS compatibility

fixRequire
- Fixes dynamic require statements in CommonJS build
- Replaces \_require('url') with require('url')

fixWasmDirInNode
- Updates WASM file paths in Node.js builds
- Changes kzg-node.wasm → kzg.wasm → ../wasm/kzg.wasm

fixWasmDirInWeb
- Updates WASM file paths in browser builds
- Changes kzg-web.wasm → ../wasm/kzg.wasm

#### Build Output Structure

`
dist/
├── cjs/ # CommonJS build for Node.js
│ ├── index.js
│ ├── kzg.js
│ ├── loader.cjs
│ └── package.json
├── esm/ # ES Modules build
│ ├── index.js
│ ├── kzg.js
│ ├── loader.mjs
│ └── package.json
├── browser/ # Browser build
│ ├── index.js
│ ├── kzg.js
│ └── package.json
└── wasm/ # WASM binary
└── kzg.wasm
`

#### Testing Builds

`bash


Test all builds

npm test

Test specific builds

npm run test:dist # Test distribution build
npm run test:src # Test source code
npm run test:browser # Test browser environment
``