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Crypto: Difference between revisions

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===Cryptographically Random Values===
===Cryptographically Random Values===


A <b id=concept-cryptographically-random-values title=concept-cryptographically-random-values>cryptographically random value</b> is a value generated from a cryptographically strong pseudo-random number generator seeded with truly random values.  In practice, implementations should 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.
A <b id=concept-cryptographically-random-values title=concept-cryptographically-random-values>cryptographically random value</b> is a value generated from a cryptographically strong pseudo-random number generator seeded with truly random values.  In practice, implementations should generate cryptographically random values using well-established cryptographic pseudo-random number generators 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 <code title>Crypto</code>==
==Interface <code title>Crypto</code>==

Revision as of 20:02, 13 August 2012

The current specification for the window.Crypto API can now be found in the Web Cryptography API being developed by the W3C Web Cryptography Working Group.

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 seeded with truly random values. In practice, implementations should generate cryptographically random values using well-established cryptographic pseudo-random number generators 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 Crypto

interface Crypto {
  ArrayBufferView getRandomValues(in ArrayBufferView array);
};

partial interface Window {
  readonly attribute Crypto crypto;
};

The getRandomValues(array) must run the following steps:

  1. array is an ArrayBufferView. If array is not of an integer type (i.e., Int8Array, Uint8Array, Int16Array, Uint16Array, Int32Array, or Uint32Array), throw a TypeMismatchError and abort these steps.
  2. If array's length is greater than 65536, throw a QuotaExceededError and abort these steps.
  3. Overwrite all elements of array with cryptographically random values of the appropriate type.
  4. Return array.