@lodestar/beacon-node/lib/util/blobs.js

A Typescript implementation of the beacon chain

import { digest as sha256Digest } from "@chainsafe/as-sha256";
import { Tree } from "@chainsafe/persistent-merkle-tree";
import { KZG_COMMITMENT_GINDEX0, VERSIONED_HASH_VERSION_KZG } from "@lodestar/params";
import { signedBlockToSignedHeader } from "@lodestar/state-transition";
import { ssz } from "@lodestar/types";
export function kzgCommitmentToVersionedHash(kzgCommitment) {
    const hash = sha256Digest(kzgCommitment);
    // Equivalent to `VERSIONED_HASH_VERSION_KZG + hash(kzg_commitment)[1:]`
    hash[0] = VERSIONED_HASH_VERSION_KZG;
    return hash;
}
export function computeInclusionProof(fork, body, index) {
    const bodyView = ssz[fork].BeaconBlockBody.toView(body);
    const commitmentGindex = KZG_COMMITMENT_GINDEX0 + index;
    return new Tree(bodyView.node).getSingleProof(BigInt(commitmentGindex));
}
export function computeBlobSidecars(config, signedBlock, contents) {
    const blobKzgCommitments = signedBlock.message.body.blobKzgCommitments;
    if (blobKzgCommitments === undefined) {
        throw Error("Invalid block with missing blobKzgCommitments for computeBlobSidecars");
    }
    const signedBlockHeader = signedBlockToSignedHeader(config, signedBlock);
    const fork = config.getForkName(signedBlockHeader.message.slot);
    return blobKzgCommitments.map((kzgCommitment, index) => {
        const blob = contents.blobs[index];
        const kzgProof = contents.kzgProofs[index];
        const kzgCommitmentInclusionProof = contents.kzgCommitmentInclusionProofs?.[index] ?? computeInclusionProof(fork, signedBlock.message.body, index);
        return { index, blob, kzgCommitment, kzgProof, signedBlockHeader, kzgCommitmentInclusionProof };
    });
}
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