use ChaCha⊕AES encryption #1164

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opened 2010-08-09 22:00:12 +00:00 by zooko · 15 comments

In order to protect against weaknesses in AES (such as timing or side-channel attacks, or cryptanalysis, possibly far in the future and applied against old ciphertexts), want to use a combined encryption of AES-128 and XSalsa20. Yu Xue (Student) and Jack Lloyd (Mentor) are working on implementing that mode for GSoC 2010:

[//trac/pycryptopp/ticket/46 https://tahoe-lafs.org/trac/pycryptopp/ticket/46]

This ticket is to integrate that encryption mode into Tahoe-LAFS. The steps are to define new capability versions, such as by inserting an X into the cap type designator:

[//pipermail/tahoe-dev/2010-August/004878.html https://tahoe-lafs.org/pipermail/tahoe-dev/2010-August/004878.html]
[//pipermail/tahoe-dev/2010-August/004879.html https://tahoe-lafs.org/pipermail/tahoe-dev/2010-August/004879.html]

And to make it so that caps of that new type get encrypted/decrypted with XSalsa20+AES-128 instead of with AES-256. For the first release of Tahoe-LAFS which includes that functionality, it will still by default create new caps using the old encryption of only AES-256. It is important that people feel free to upgrade to new versions of Tahoe-LAFS without having to take any steps to ensure backward-compatibility, and that means that the new version of Tahoe-LAFS must not, by default, produce caps that older versions of Tahoe-LAFS (such as v1.8.0) can't read.

[//pipermail/tahoe-dev/2010-August/004936.html This tahoe-dev letter] listed all the places where the source code as of Tahoe-LAFS v1.8.0c1 used encryption. Here are those links updated to current master:

  • source:src/allmydata/dirnode.py@35f37cc5#L175
  • source:src/allmydata/dirnode.py@35f37cc5#L294
  • source:src/allmydata/immutable/filenode.py@0ef59394#L185
  • source:src/allmydata/immutable/upload.py@196bd583#L620
  • source:src/allmydata/immutable/upload.py@196bd583#L738
  • source:src/allmydata/mutable/filenode.py@4563ba45#L161
  • source:src/allmydata/mutable/filenode.py@4563ba45#L166
  • source:src/allmydata/mutable/publish.py@45adde71#L693
  • source:src/allmydata/mutable/retrieve.py@7956e22d#L883
  • source:src/allmydata/util/fileutil.py@c85060c4#L118

This is inspired by The One-Hundred-Year Cryptography Project.

In order to protect against weaknesses in AES (such as timing or side-channel attacks, or cryptanalysis, possibly far in the future and applied against old ciphertexts), want to use a combined encryption of AES-128 and XSalsa20. Yu Xue (Student) and Jack Lloyd (Mentor) are working on implementing that mode for GSoC 2010: [//trac/pycryptopp/ticket/46 <https://tahoe-lafs.org/trac/pycryptopp/ticket/46>] This ticket is to integrate that encryption mode into Tahoe-LAFS. The steps are to define new capability versions, such as by inserting an `X` into the cap type designator: [//pipermail/tahoe-dev/2010-August/004878.html <https://tahoe-lafs.org/pipermail/tahoe-dev/2010-August/004878.html>] [//pipermail/tahoe-dev/2010-August/004879.html <https://tahoe-lafs.org/pipermail/tahoe-dev/2010-August/004879.html>] And to make it so that caps of that new type get encrypted/decrypted with XSalsa20+AES-128 instead of with AES-256. For the first release of Tahoe-LAFS which includes that functionality, it will still by default create new caps using the old encryption of only AES-256. It is important that people feel free to upgrade to new versions of Tahoe-LAFS without having to take any steps to ensure backward-compatibility, and that means that the new version of Tahoe-LAFS *must not*, by default, produce caps that older versions of Tahoe-LAFS (such as v1.8.0) can't read. [//pipermail/tahoe-dev/2010-August/004936.html This tahoe-dev letter] listed all the places where the source code as of Tahoe-LAFS v1.8.0c1 used encryption. Here are those links updated to current master: * source:src/allmydata/dirnode.py@35f37cc5#L175 * source:src/allmydata/dirnode.py@35f37cc5#L294 * source:src/allmydata/immutable/filenode.py@0ef59394#L185 * source:src/allmydata/immutable/upload.py@196bd583#L620 * source:src/allmydata/immutable/upload.py@196bd583#L738 * source:src/allmydata/mutable/filenode.py@4563ba45#L161 * source:src/allmydata/mutable/filenode.py@4563ba45#L166 * source:src/allmydata/mutable/publish.py@45adde71#L693 * source:src/allmydata/mutable/retrieve.py@7956e22d#L883 * source:src/allmydata/util/fileutil.py@c85060c4#L118 This is inspired by [The One-Hundred-Year Cryptography Project](wiki/OneHundredYearCryptography).
zooko added the
code
major
defect
1.8β
labels 2010-08-09 22:00:12 +00:00
zooko added this to the undecided milestone 2010-08-09 22:00:12 +00:00
zooko modified the milestone from undecided to 1.9.0 2010-08-09 22:16:28 +00:00
Author

Upon Samuel Neves's questioning, I added some notes about AES-128 vs. AES-256 for this:

(@@http://tahoe-lafs.org/trac/pycryptopp/ticket/46#comment:-1@@)

I would be interested in the feedback of Jack, Yu Xue, David-Sarah, or Brian about this issue.

Upon Samuel Neves's questioning, I added some notes about AES-128 vs. AES-256 for this: (@@http://tahoe-lafs.org/trac/pycryptopp/ticket/46#[comment:-1](/tahoe-lafs/trac-2024-07-25/issues/1164#issuecomment--1)@@) I would be interested in the feedback of Jack, Yu Xue, David-Sarah, or Brian about this issue.
zooko added
enhancement
and removed
defect
labels 2010-09-29 05:07:19 +00:00
zooko modified the milestone from 1.9.0 to soon 2011-04-24 04:05:49 +00:00
zooko modified the milestone from soon to 1.10.0 2011-04-24 04:07:01 +00:00
Author

Yu Xue contributed a patch to pycryptopp to make it support XSalsa20 and XSalsa20⊕AES-128: http://tahoe-lafs.org/trac/pycryptopp/ticket/46

Yu Xue contributed a patch to pycryptopp to make it support XSalsa20 and XSalsa20⊕AES-128: <http://tahoe-lafs.org/trac/pycryptopp/ticket/46>
davidsarah commented 2012-03-29 21:10:01 +00:00
Owner

It's not clear to me that this should go into 1.10, which is going to focus primarily on bug fixes (especially robustifying mutable files and repair behaviour) and accounting. However, I may be persuadable.

It's not clear to me that this should go into 1.10, which is going to focus primarily on bug fixes (especially robustifying mutable files and repair behaviour) and accounting. However, I may be persuadable.
davidsarah commented 2012-03-29 21:31:12 +00:00
Owner

Hmm, I see this is explicitly listed as one of the goals for the 1.10 milestone. So, I'll leave it in.

Hmm, I see this is explicitly listed as one of the goals for the 1.10 milestone. So, I'll leave it in.
Author

I currently intend to get this landed in trunk for Tahoe-LAFS v1.11.

I currently intend to get this landed in trunk for Tahoe-LAFS v1.11.
davidsarah commented 2012-10-11 20:09:42 +00:00
Owner

Replying to zooko:

I currently intend to get this landed in trunk for Tahoe-LAFS v1.11.

+1.

Replying to [zooko](/tahoe-lafs/trac-2024-07-25/issues/1164#issuecomment-79290): > I currently intend to get this landed in trunk for Tahoe-LAFS v1.11. +1.
daira commented 2013-07-18 19:14:00 +00:00
Owner

We pushed many goals back a release when we decided to have release 1.10 just based on features and bugfixes that were already on trunk. So it is now 1.11 that is going to focus primarily on robustifying share placement and repair behaviour. I suggest that XSalsa+AES support go into 1.12, unless it is ready for 1.11 without slipping the schedule. Note that some design issues about cap format etc. have not been resolved yet.

We pushed many goals back a release when we decided to have release 1.10 just based on features and bugfixes that were already on trunk. So it is now 1.11 that is going to focus primarily on robustifying share placement and repair behaviour. I suggest that XSalsa+AES support go into 1.12, unless it is ready for 1.11 without slipping the schedule. Note that some design issues about cap format etc. have not been resolved yet.
tahoe-lafs modified the milestone from 1.11.0 to soon 2013-07-18 19:14:00 +00:00
Author

Replying to daira:

I suggest that XSalsa+AES support go into 1.12, unless it is ready for 1.11 without slipping the schedule.

+1

Replying to [daira](/tahoe-lafs/trac-2024-07-25/issues/1164#issuecomment-79292): > I suggest that XSalsa+AES support go into 1.12, unless it is ready for 1.11 without slipping the schedule. +1
tahoe-lafs modified the milestone from soon to 1.12.0 2013-07-22 20:42:02 +00:00
Author

Because of the fact that ChaCha looks like it might become a standard cipher in TLS soon (http://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-01), then this makes me think we should use ChaCha instead of XSalsa20 for this.

Because of the fact that ChaCha looks like it might become a standard cipher in TLS soon (<http://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-01>), then this makes me think we should use ChaCha instead of XSalsa20 for this.
Author

I opened [//trac/pycryptopp/ticket/15#comment:79286 pycryptopp ticket #94] to track adding ChaCha into pycryptopp.

I opened [//trac/pycryptopp/ticket/15#[comment:79286](/tahoe-lafs/trac-2024-07-25/issues/1164#issuecomment-79286) pycryptopp ticket #94] to track adding ChaCha into pycryptopp.
zooko changed title from use XSalsa20+AES-128 encryption to use ChaCha⊕AES encryption 2013-10-11 11:32:38 +00:00

Milestone renamed

Milestone renamed
warner modified the milestone from 1.12.0 to 1.13.0 2016-03-22 05:02:25 +00:00

renaming milestone

renaming milestone
warner modified the milestone from 1.13.0 to 1.14.0 2016-06-28 18:17:14 +00:00
daira commented 2016-08-04 14:52:59 +00:00
Owner

As part of the programme of reducing our cryptography library dependencies (and getting out of the business of writing C/Python wrappers ourselves), I think we should move away from pycryptopp and use 'cryptography' (which Tahoe-LAFS already depends on via pyOpenSSL >= 0.14) where possible. It doesn't look like cryptography supports ChaCha20 unfortunately; we could either fix that, or use pysodium for that instead.

As part of the programme of reducing our cryptography library dependencies (and getting out of the business of writing C/Python wrappers ourselves), I think we should move away from pycryptopp and use '[cryptography](https://cryptography.io/en/latest/hazmat/primitives/)' (which Tahoe-LAFS already depends on via pyOpenSSL >= 0.14) where possible. It doesn't look like cryptography supports [ChaCha](wiki/ChaCha)20 unfortunately; we could either fix that, or use pysodium for that instead.

Moving open issues out of closed milestones.

Moving open issues out of closed milestones.
exarkun modified the milestone from 1.14.0 to 1.15.0 2020-06-30 14:45:13 +00:00
Owner

Ticket retargeted after milestone closed

Ticket retargeted after milestone closed
meejah modified the milestone from 1.15.0 to soon 2021-03-30 18:40:19 +00:00
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