mirror of
https://github.com/tahoe-lafs/tahoe-lafs.git
synced 2024-12-25 07:31:07 +00:00
118 lines
5.3 KiB
ReStructuredText
118 lines
5.3 KiB
ReStructuredText
.. -*- coding: utf-8-with-signature -*-
|
|
|
|
Welcome to Tahoe-LAFS!
|
|
======================
|
|
|
|
Welcome to Tahoe-LAFS_, the first decentralized storage system with
|
|
*provider-independent security*.
|
|
|
|
.. _Tahoe-LAFS: https://tahoe-lafs.org
|
|
|
|
What is "provider-independent security"?
|
|
========================================
|
|
|
|
Every seller of cloud storage services will tell you that their service is
|
|
"secure". But what they mean by that is something fundamentally different
|
|
from what we mean. What they mean by "secure" is that after you've given
|
|
them the power to read and modify your data, they try really hard not to let
|
|
this power be abused. This turns out to be difficult! Bugs,
|
|
misconfigurations, or operator error can accidentally expose your data to
|
|
another customer or to the public, or can corrupt your data. Criminals
|
|
routinely gain illicit access to corporate servers. Even more insidious is
|
|
the fact that the employees themselves sometimes violate customer privacy out
|
|
of carelessness, avarice, or mere curiosity. The most conscientious of
|
|
these service providers spend considerable effort and expense trying to
|
|
mitigate these risks.
|
|
|
|
What we mean by "security" is something different. *The service provider
|
|
never has the ability to read or modify your data in the first place: never.*
|
|
If you use Tahoe-LAFS, then all of the threats described above are non-issues
|
|
to you. Not only is it easy and inexpensive for the service provider to
|
|
maintain the security of your data, but in fact they couldn't violate its
|
|
security if they tried. This is what we call *provider-independent
|
|
security*.
|
|
|
|
This guarantee is integrated naturally into the Tahoe-LAFS storage system and
|
|
doesn't require you to perform a manual pre-encryption step or cumbersome key
|
|
management. (After all, having to do cumbersome manual operations when
|
|
storing or accessing your data would nullify one of the primary benefits of
|
|
using cloud storage in the first place: convenience.)
|
|
|
|
Here's how it works:
|
|
|
|
.. image:: network-and-reliance-topology.svg
|
|
|
|
A "storage grid" is made up of a number of storage servers. A storage server
|
|
has direct attached storage (typically one or more hard disks). A "gateway"
|
|
communicates with storage nodes, and uses them to provide access to the
|
|
file store over protocols such as HTTP(S), SFTP or FTP.
|
|
|
|
Note that you can find "client" used to refer to gateway nodes (which act as
|
|
a client to storage servers), and also to processes or programs connecting to
|
|
a gateway node and performing operations on the grid -- for example, a CLI
|
|
command, Web browser, SFTP client, or FTP client.
|
|
|
|
Users do not rely on storage servers to provide *confidentiality* nor
|
|
*integrity* for their data -- instead all of the data is encrypted and
|
|
integrity-checked by the gateway, so that the servers can neither read nor
|
|
modify the contents of the files.
|
|
|
|
Users do rely on storage servers for *availability*. The ciphertext is
|
|
erasure-coded into ``N`` shares distributed across at least ``H`` distinct
|
|
storage servers (the default value for ``N`` is 10 and for ``H`` is 7) so
|
|
that it can be recovered from any ``K`` of these servers (the default
|
|
value of ``K`` is 3). Therefore only the failure of ``H-K+1`` (with the
|
|
defaults, 5) servers can make the data unavailable.
|
|
|
|
In the typical deployment mode each user runs her own gateway on her own
|
|
machine. This way she relies on her own machine for the confidentiality and
|
|
integrity of the data.
|
|
|
|
An alternate deployment mode is that the gateway runs on a remote machine and
|
|
the user connects to it over HTTPS or SFTP. This means that the operator of
|
|
the gateway can view and modify the user's data (the user *relies on* the
|
|
gateway for confidentiality and integrity), but the advantage is that the
|
|
user can access the file store with a client that doesn't have the gateway
|
|
software installed, such as an Internet kiosk or cell phone.
|
|
|
|
Access Control
|
|
==============
|
|
|
|
There are two kinds of files: immutable and mutable. When you upload a file
|
|
to the storage grid you can choose which kind of file it will be in the
|
|
grid. Immutable files can't be modified once they have been uploaded. A
|
|
mutable file can be modified by someone with read-write access to it. A user
|
|
can have read-write access to a mutable file or read-only access to it, or no
|
|
access to it at all.
|
|
|
|
A user who has read-write access to a mutable file or directory can give
|
|
another user read-write access to that file or directory, or they can give
|
|
read-only access to that file or directory. A user who has read-only access
|
|
to a file or directory can give another user read-only access to it.
|
|
|
|
When linking a file or directory into a parent directory, you can use a
|
|
read-write link or a read-only link. If you use a read-write link, then
|
|
anyone who has read-write access to the parent directory can gain read-write
|
|
access to the child, and anyone who has read-only access to the parent
|
|
directory can gain read-only access to the child. If you use a read-only
|
|
link, then anyone who has either read-write or read-only access to the parent
|
|
directory can gain read-only access to the child.
|
|
|
|
For more technical detail, please see the `the doc page`_ on the Wiki.
|
|
|
|
.. _the doc page: https://tahoe-lafs.org/trac/tahoe-lafs/wiki/Doc
|
|
|
|
Get Started
|
|
===========
|
|
|
|
To use Tahoe-LAFS, please see quickstart.rst_.
|
|
|
|
.. _quickstart.rst: quickstart.rst
|
|
|
|
License
|
|
=======
|
|
|
|
Tahoe-LAFS is an open-source project; please see README.rst_ for details.
|
|
|
|
.. _README.rst: ../README.rst
|