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bc96439261
Using a weak RNG for the form boundary allows a website operator to perform several attacks on users (as outlined in https://trac.torproject.org/projects/tor/ticket/22919) These include: - Identifying Windows users based on the unseeded RNG - Identify the number of form submissions that have occurred cross-origin between same-origin submissions Additionally, a predictable boundary makes it possible to forge a boundary in the middle of a file upload. Differential Revision: https://phabricator.services.mozilla.com/D56056 --HG-- extra : moz-landing-system : lando
42 lines
1.3 KiB
C++
42 lines
1.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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/* Routines for generating random numbers */
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#ifndef mozilla_RandomNum_h_
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#define mozilla_RandomNum_h_
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#include "mozilla/Maybe.h"
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#include "mozilla/Types.h"
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namespace mozilla {
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/**
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* Generate a cryptographically secure random 64-bit unsigned number using the
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* best facilities available on the current OS.
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*
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* Useful whenever a secure random number is needed and NSS isn't available.
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* (Perhaps because it hasn't been initialized yet)
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*
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* Current mechanisms:
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* Windows: RtlGenRandom()
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* Android, Darwin, DragonFly, FreeBSD, OpenBSD, NetBSD: arc4random()
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* Linux: getrandom() if available, "/dev/urandom" otherwise
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* Other Unix: "/dev/urandom"
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*
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*/
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MFBT_API Maybe<uint64_t> RandomUint64();
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/**
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* Like RandomUint64, but always returns a uint64_t or crashes with an assert
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* if the underlying RandomUint64 call failed.
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*/
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MFBT_API uint64_t RandomUint64OrDie();
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} // namespace mozilla
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#endif // mozilla_RandomNum_h_
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