Function parallel_hash256 

pub fn parallel_hash256(
    data: &[u8],
    block_size: usize,
    customization: &[u8],
    out: &mut [u8],
) -> Result<(), CryptoError>

ParallelHash256 with fixed output length (NIST SP 800-185 §6.2).

Hashes data in block_size-byte blocks with optional customization string S; the output length is out.len() bytes.

Errors

Returns CryptoError::BadInput if block_size is 0 or a length computation overflows (unreachable in practice).