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annotate doc/encryption.rst @ 3950:8f87ff449a34

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doc: new doc giving an overview on how e2ee is working in Libervia/XMPP: the doc explain pubsub e2ee for now rel 380
author Goffi <goffi@goffi.org>
date Sat, 15 Oct 2022 20:38:33 +0200
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children 9f85369294f3
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1 .. _encryption:
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3 ===========================
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4 Encryption in Libervia/XMPP
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5 ===========================
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7 Libervia being an XMPP client, it handles encryption between client and server, then the
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8 message is encrypted between servers, and finally to deliver to target client(s).
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10 This avoid the communication to be accessible from people having access to the network,
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11 but the communications are available to server administrators, or administrators of
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12 services that you may use (e.g. pubsub service).
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14 To make your communications inaccessible to anybody but your recipient(s), end-to-end
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15 encryption (or e2ee) may be used. This page aims to explain roughly how it is done in
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16 Libervia and XMPP so end-user can understand and exploit it correctly.
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18 .. note::
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20 this page is work in progress, it will be completed over time to explain the whole
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21 machanism. Is something is not clear, please contact the development team at the XMPP
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22 room `libervia@chat.jabberfr.org <xmpp:libervia@chat.jabberfr.org?join>`__ to get
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23 details and help to improve this documentation.
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26 .. _pubsub-encryption:
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28 Pubsub Encryption
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29 =================
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31 By default, pubsub items are in plain text (i.e. not encrypted, beside the normal
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32 encryption between client and server, and between servers). This is often the desired
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33 behaviour as pubsub is often used for public matters (public blogs, events, or other kind
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34 of data).
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36 However, pubsub may also be used for private matters, to keep safe some of your own data,
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37 or to uses all other kind of features privately (private blog, event organization, etc).
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39 To make private pubsub node, in addition to the access model which restrict entities which
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40 can retrieve its item, it is possible to use end-to-end encryption.
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42 Pubsub is not encrypted the same way as messages, because you generally need to access all
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43 items of a pubsub node, even if you get access to the node once items have already been
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44 published.
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46 E2ee is currently done using `OpenPGP`_ (or OX for PubSub: OXPS). Each item is encrypted
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47 using a **symmetric** encryption, which mean that the same key (called "shared secret") is
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48 used both to encrypt and decrypt an item, and is shared between all people who must access
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49 or publish to the pubsub node (i.e. blog, event calendar, etc). This is done this way to
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50 make it easy to add a new members, who can then access all archives of the node, but this
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51 also means that if the shared secret is compromised (i.e. somebody who should not has
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52 obtained a copy), all items made with this secret are accessible to the persons in
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53 possession of the secret.
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55 .. note::
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57 OXPS specification is not currently an official XEP (XMPP Extension Protocol), it is
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58 about to be examinated by "XMPP council". This documentation will be updated with the
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59 evolution of the situation. You can read current specification proposal at
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60 https://xmpp.org/extensions/inbox/pubsub-encryption.html (which is inaccessible due to
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61 a 404 error at the time of writting, this should be fixed hopefully when you read this
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62 documentation).
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63
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64 To make an encrypted pubsub node accessible to somebody, you need to share the secret with
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65 them.
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66
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67 You can see that as the key of a house: everybody who has a copy of the key can go inside
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68 the house, and bring something or take pictures. Sharing the secret is like making
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69 a copy of the key and giving it to the person.
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71 If you think that your shared secret is compromised (obtained by somebody who shouldn't),
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72 or if you want to remove access to somebody, you can "rotate" the secret, which means that
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73 every existing key is revoked (flagged as "you should not use it anymore to write
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74 something", but you can still use it to read archives), and a new one is created (to write
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75 new items).
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77 With the house analogy, it's like changing the locks, and giving new keys to trusted
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78 people: people with the older keys can't go inside the house anymore, but if they have
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79 taken pictures before the key has been changed, theirs pictures is still in their
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80 possession.
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81
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82 .. attention::
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84 If you rotate the shared secret, new items are using the new secret, but all items
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85 which were existing before the secret rotation stay accessible to people who had access
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86 to former secrets (the pubsub node can refuse access to them though). If malicious
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87 people had access to items before, they could have made copy anytime, thus there is
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88 little point in reencrypting everything.
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89
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90 To handle encrypted pubsub node shared secrets from command line, you may use
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91 :ref:`libervia-cli_pubsub_secret`.
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93 .. _OpenPGP: https://en.wikipedia.org/wiki/Pretty_Good_Privacy#OpenPGP
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94