@dsnp/hash-util

Overview

This package is a TypeScript implementation of hash-related utilities to support DSNP applications and services.

Background

DSNP anchors content to announcements via a URL and hashes. This ensures integrity of resources and also provides for relocatable content, as hashes can be generated and verified regardless of location.

This library provides a simple implementation that checks whether a data "file" matches at least one of the hash values provided.

Dependencies

This library utilizes a number of open source projects and the authors are grateful for the efforts of the following projects:

• The Multiformats Project, which specifies multihashes, multibase encodings, and CIDs, among other things
• IPLD (InterPlanetary Linked Data), used for the dag-pb codec
• IPFS (InterPlanetary File System), a content addressed distributed file system

Usage

Given a Uint8Array and an array of strings representing DSNP hashes, use the following function to verify if there is a matching hash.

import { compareBinaryToMultibaseHashes } from "@dsnp/hash-util";

const result = await compareBinaryToMultibaseHashes(binaryU8A, hashes);

It can also be used to generate the CID for a Uint8Array (this is used internally in compareBinaryToMultibaseHashes):

import { generateCID } from "@dsnp/hash-util";

const cidString = await generateCID(binaryU8A);

Compatibility

The library will verify the following types of hashes:

• multihash values
  • any standard multibase encoding e.g. base32 or base58btc
  • sha2-256 or blake2b-256 hash
• CID version 1 values as emitted by the default configuration of ipfs add --cid-version=1 ...
  • base32 base encoding
  • dag-pb codec for input longer than 256*1024 bytes
  • raw codec for shorter (single-block) input
  • sha2-256 hash

Limitations

All comparisons are done in-memory, meaning that there is no attempt to limit the size of the byte array or memory requirements. Callers should therefore perform their own sanity checks.

Development

npm i
npm run build
npm run test

Please use the github issues area to report bugs or suggest enhancements. Pull requests are gratefully welcomed.