hash

bun add @stopcock/hash

import { sha256, crc32, toHex, hmac } from '@stopcock/hash'

toHex(sha256('hello'))        // "2cf24dba..."
crc32('hello')                // 907060870
toHex(hmac(sha256, 'key', 'msg'))

Real-world patterns

Content-addressable cache key

import { sha256, toHex } from '@stopcock/hash'

const cacheKey = (body: string) => toHex(sha256(body)).slice(0, 16)
const key = cacheKey(JSON.stringify(requestBody))
// "a3f2b7c9e1d04f8a" → use as Redis/cache key

HMAC signature verification

import { sha256, hmac, timeSafeEqual, fromHex } from '@stopcock/hash'

const verify = (payload: string, signature: string, secret: string) =>
  timeSafeEqual(hmac(sha256, secret, payload), fromHex(signature))

// Verify a webhook from a third party
const valid = verify(rawBody, req.headers['x-signature'], WEBHOOK_SECRET)

Fast dedup with xxHash

import { xxhash32 } from '@stopcock/hash'

const seen = new Set<number>()
const deduped = items.filter(item => {
  const hash = xxhash32(JSON.stringify(item))
  if (seen.has(hash)) return false
  seen.add(hash)
  return true
})

Hash functions

sha256(input: string | Uint8Array): Uint8Array
md5(input: string | Uint8Array): Uint8Array
xxhash32(input: string | Uint8Array, seed?: number): number
crc32(input: string | Uint8Array): number

sha256 and md5 return Uint8Array. Use toHex or toBase64 to format. xxhash32 and crc32 return numbers directly.

Utilities

toHex(data: Uint8Array): string
toBase64(data: Uint8Array): string
fromHex(hex: string): Uint8Array
hmac(hashFn: (data: Uint8Array) => Uint8Array, key: string | Uint8Array, message: string | Uint8Array): Uint8Array
timeSafeEqual(a: Uint8Array, b: Uint8Array): boolean