direct SSL certificate pinning for check.torproject.org and torproject.org (curl method)

[phabricator-migrator]

Information

ID: 80
PHID: PHID-TASK-tsull3kmksftqnvdtfgy
Author: Patrick
Status at Migration Time: open
Priority at Migration Time: Normal

Description

Migrated from:
https://github.com/Whonix/Whonix/issues/24

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Info:

Terminology in this field is ambiguous. “(public key) pinning” is easily misunderstood. Not to be confused with SSL Certificate Authority (CA) Pinning! This ticket is for pinning the exact certificate.

TPO offers fingerprints on their website.

TPO offers no hidden services that could be used as alternative anymore.

wget has no feature for direct certificate pinning (feature request).

#whonixcheck has an unfinished --pin-tpo-cert feature.

Status:

Whonix 14 will be based on Debian stretch, so this could now be implemented.

TODO: Implement using curl and --pinnedpubkey

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Enable this by default or not?

If you want to discuss if this should be enabled by default or not, please see Defaults Discussion and create a child ticket.

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Related tickets:

• sdwdate uses onions rather than SSL: T131
• wget local CA alternative workaround: T81
• openssl sclient method: T82
• python method: T146

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TODO:

• Wait for curl 7.39.0 to appear in Debian. Done, stretch comes with curl 7.51.
• Implement this in #whonixcheck and #tb-updater.

Comments

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HulaHoop

2015-12-07 15:41:45 UTC

This may not be needed if TPO switches to Let’s Encrypt for its own sites. It would be as simple as trusting their CA without worrying about expired certs or MITM.

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HulaHoop

2015-12-08 19:36:22 UTC

Security comparison:

Self-signed cert > Let’s Encrypt > Current CA model

Our options are limited but what TPO decides to proceed so we need to ask them and get an idea.

To be researched: The implications of NSLs on Let’s Encrypt’s security.

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Patrick

2015-12-08 19:46:18 UTC

letsencrypt should go into it’s own ticket. Not good to have it under
“direct SSL certificate pinning”.

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HulaHoop

2016-03-01 00:04:56 UTC

[tor-talk] Lets Encrypt compared to self-signed certs

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HulaHoop

2016-03-01 18:37:12 UTC

Key level pinning is not coded yet but planned. Lets Encrypt logs can be checked by users for signs of strange behavior or sudden key changes. Lets Encrypt aims for great transparency and will fight to defeat NSLs but As a CA this type of legal attack can happen. Sticking to the previous idea of direct cert pinning makes more sense for usability and security IMO.

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HulaHoop

2018-10-13 12:47:08 UTC

We can now grab the browser tarball from the TPO onion instead which makes this ticket obsolete. Close if you concur.