lighthouse/beacon_node/beacon_chain/src/kzg_utils.rs

use kzg::{Blob as KzgBlob, Error as KzgError, Kzg};
use types::{Blob, EthSpec, Hash256, KzgCommitment, KzgProof};

/// Converts a blob ssz List object to an array to be used with the kzg
/// crypto library.
fn ssz_blob_to_crypto_blob<E: EthSpec>(blob: &Blob<E>) -> Result<KzgBlob, KzgError> {
    KzgBlob::from_bytes(blob.as_ref()).map_err(Into::into)
}

/// Validate a single blob-commitment-proof triplet from a `BlobSidecar`.
pub fn validate_blob<E: EthSpec>(
    kzg: &Kzg,
    blob: &Blob<E>,
    kzg_commitment: KzgCommitment,
    kzg_proof: KzgProof,
) -> Result<(), KzgError> {
    let _timer = crate::metrics::start_timer(&crate::metrics::KZG_VERIFICATION_SINGLE_TIMES);
    let kzg_blob = ssz_blob_to_crypto_blob::<E>(blob)?;
    kzg.verify_blob_kzg_proof(&kzg_blob, kzg_commitment, kzg_proof)
}

/// Validate a batch of blob-commitment-proof triplets from multiple `BlobSidecars`.
pub fn validate_blobs<E: EthSpec>(
    kzg: &Kzg,
    expected_kzg_commitments: &[KzgCommitment],
    blobs: Vec<&Blob<E>>,
    kzg_proofs: &[KzgProof],
) -> Result<(), KzgError> {
    let _timer = crate::metrics::start_timer(&crate::metrics::KZG_VERIFICATION_BATCH_TIMES);
    let blobs = blobs
        .into_iter()
        .map(|blob| ssz_blob_to_crypto_blob::<E>(blob))
        .collect::<Result<Vec<_>, KzgError>>()?;

    kzg.verify_blob_kzg_proof_batch(&blobs, expected_kzg_commitments, kzg_proofs)
}

/// Compute the kzg proof given an ssz blob and its kzg commitment.
pub fn compute_blob_kzg_proof<E: EthSpec>(
    kzg: &Kzg,
    blob: &Blob<E>,
    kzg_commitment: KzgCommitment,
) -> Result<KzgProof, KzgError> {
    let kzg_blob = ssz_blob_to_crypto_blob::<E>(blob)?;
    kzg.compute_blob_kzg_proof(&kzg_blob, kzg_commitment)
}

/// Compute the kzg commitment for a given blob.
pub fn blob_to_kzg_commitment<E: EthSpec>(
    kzg: &Kzg,
    blob: &Blob<E>,
) -> Result<KzgCommitment, KzgError> {
    let kzg_blob = ssz_blob_to_crypto_blob::<E>(blob)?;
    kzg.blob_to_kzg_commitment(&kzg_blob)
}

/// Compute the kzg proof for a given blob and an evaluation point z.
pub fn compute_kzg_proof<E: EthSpec>(
    kzg: &Kzg,
    blob: &Blob<E>,
    z: Hash256,
) -> Result<(KzgProof, Hash256), KzgError> {
    let z = z.0.into();
    let kzg_blob = ssz_blob_to_crypto_blob::<E>(blob)?;
    kzg.compute_kzg_proof(&kzg_blob, &z)
        .map(|(proof, z)| (proof, Hash256::from_slice(&z.to_vec())))
}

/// Verify a `kzg_proof` for a `kzg_commitment` that evaluating a polynomial at `z` results in `y`
pub fn verify_kzg_proof<E: EthSpec>(
    kzg: &Kzg,
    kzg_commitment: KzgCommitment,
    kzg_proof: KzgProof,
    z: Hash256,
    y: Hash256,
) -> Result<bool, KzgError> {
    kzg.verify_kzg_proof(kzg_commitment, &z.0.into(), &y.0.into(), kzg_proof)
}