Crypto

Overview

This document describes a proposal for the window.crypto API.

Definitions

Cryptographically Random Values

A cryptographically random value is a value generated from a cryptographically strong pseudo-random number generator when seeded with truly random values. In practice, implementations generate cryptographically random values using well-established cryptographic pseudo-random number generators, such as RC4, seeded with high-quality entropy, such as from an operating-system entropy source (e.g., /dev/urandom). This document provides no lower-bound on the information theoretic entropy present in cryptographically random values, but implementations should make a best effort to provide as much entropy as practicable.

Interface

[NoInterfaceObject]
interface Crypto {
  void getRandomValues(in ArrayBufferView array);
};

[Suplemental, NoInterfaceObject]
interface Window {
  readonly attribute Crypto crypto;
};

Methods

getRandomValues

The getRandomValues method fills array with random data. Specifically, if array is an ArrayBufferView of an integer type (i.e., Int8Array, Uint8Array, Int16Array, Uint16Array, Int32Array, or Uint32Array), then all the elements of array are overwritten with cryptographically random values. If array is not of an appropriate type, getRandomValues throws a TYPE_MISMATCH_ERR. If no cryptographically random values are available, getRandomValues throws a NOT_SUPPORTED_ERR.