index.js

var assert = require('nanoassert')
var b4a = require('b4a')

var wasm = null
var wasmPromise = typeof WebAssembly !== "undefined" && require('./blake2b')().then(mod => {
  wasm = mod
})

var head = 64
var freeList = []

module.exports = Blake2b
var BYTES_MIN = module.exports.BYTES_MIN = 16
var BYTES_MAX = module.exports.BYTES_MAX = 64
var BYTES = module.exports.BYTES = 32
var KEYBYTES_MIN = module.exports.KEYBYTES_MIN = 16
var KEYBYTES_MAX = module.exports.KEYBYTES_MAX = 64
var KEYBYTES = module.exports.KEYBYTES = 32
var SALTBYTES = module.exports.SALTBYTES = 16
var PERSONALBYTES = module.exports.PERSONALBYTES = 16

function Blake2b (digestLength, key, salt, personal, noAssert) {
  if (!(this instanceof Blake2b)) return new Blake2b(digestLength, key, salt, personal, noAssert)
  if (!wasm) throw new Error('WASM not loaded. Wait for Blake2b.ready(cb)')
  if (!digestLength) digestLength = 32

  if (noAssert !== true) {
    assert(digestLength >= BYTES_MIN, 'digestLength must be at least ' + BYTES_MIN + ', was given ' + digestLength)
    assert(digestLength <= BYTES_MAX, 'digestLength must be at most ' + BYTES_MAX + ', was given ' + digestLength)
    if (key != null) {
      assert(key instanceof Uint8Array, 'key must be Uint8Array or Buffer')
      assert(key.length >= KEYBYTES_MIN, 'key must be at least ' + KEYBYTES_MIN + ', was given ' + key.length)
      assert(key.length <= KEYBYTES_MAX, 'key must be at least ' + KEYBYTES_MAX + ', was given ' + key.length)
    }
    if (salt != null) {
      assert(salt instanceof Uint8Array, 'salt must be Uint8Array or Buffer')
      assert(salt.length === SALTBYTES, 'salt must be exactly ' + SALTBYTES + ', was given ' + salt.length)
    }
    if (personal != null) {
      assert(personal instanceof Uint8Array, 'personal must be Uint8Array or Buffer')
      assert(personal.length === PERSONALBYTES, 'personal must be exactly ' + PERSONALBYTES + ', was given ' + personal.length)
    }
  }

  if (!freeList.length) {
    freeList.push(head)
    head += 216
  }

  this.digestLength = digestLength
  this.finalized = false
  this.pointer = freeList.pop()
  this._memory = new Uint8Array(wasm.memory.buffer)

  this._memory.fill(0, 0, 64)
  this._memory[0] = this.digestLength
  this._memory[1] = key ? key.length : 0
  this._memory[2] = 1 // fanout
  this._memory[3] = 1 // depth

  if (salt) this._memory.set(salt, 32)
  if (personal) this._memory.set(personal, 48)

  if (this.pointer + 216 > this._memory.length) this._realloc(this.pointer + 216) // we need 216 bytes for the state
  wasm.blake2b_init(this.pointer, this.digestLength)

  if (key) {
    this.update(key)
    this._memory.fill(0, head, head + key.length) // whiteout key
    this._memory[this.pointer + 200] = 128
  }
}

Blake2b.prototype._realloc = function (size) {
  wasm.memory.grow(Math.max(0, Math.ceil(Math.abs(size - this._memory.length) / 65536)))
  this._memory = new Uint8Array(wasm.memory.buffer)
}

Blake2b.prototype.update = function (input) {
  assert(this.finalized === false, 'Hash instance finalized')
  assert(input instanceof Uint8Array, 'input must be Uint8Array or Buffer')

  if (head + input.length > this._memory.length) this._realloc(head + input.length)
  this._memory.set(input, head)
  wasm.blake2b_update(this.pointer, head, head + input.length)
  return this
}

Blake2b.prototype.digest = function (enc) {
  assert(this.finalized === false, 'Hash instance finalized')
  this.finalized = true

  freeList.push(this.pointer)
  wasm.blake2b_final(this.pointer)

  if (!enc || enc === 'binary') {
    return this._memory.slice(this.pointer + 128, this.pointer + 128 + this.digestLength)
  }

  if (typeof enc === 'string') {
    return b4a.toString(this._memory, enc, this.pointer + 128, this.pointer + 128 + this.digestLength)
  }

  assert(enc instanceof Uint8Array && enc.length >= this.digestLength, 'input must be Uint8Array or Buffer')
  for (var i = 0; i < this.digestLength; i++) {
    enc[i] = this._memory[this.pointer + 128 + i]
  }

  return enc
}

// libsodium compat
Blake2b.prototype.final = Blake2b.prototype.digest

Blake2b.WASM = wasm
Blake2b.SUPPORTED = typeof WebAssembly !== 'undefined'

Blake2b.ready = function (cb) {
  if (!cb) cb = noop
  if (!wasmPromise) return cb(new Error('WebAssembly not supported'))
  return wasmPromise.then(() => cb(), cb)
}

Blake2b.prototype.ready = Blake2b.ready

Blake2b.prototype.getPartialHash = function () {
  return this._memory.slice(this.pointer, this.pointer + 216);
}

Blake2b.prototype.setPartialHash = function (ph) {
  this._memory.set(ph, this.pointer);
}

function noop () {}