4 ms·

A Vulnerability in Libsodium

333 points by raggi 10mo ago

CiPHPerCoder 10mo ago
This also affected the PHP library, sodium_compat. https://github.com/FriendsOfPHP/security-advisories/pull/756 https://github.com/FriendsOfPHP/security-advisories/pull/756 I'm planning to spend my evening checking every other Ed25519 implementation I can find to see if this check is missing any where else in the open source ecosystem.
- hu3 10mo ago
  Thank you for your work on open source.
- CiPHPerCoder 10mo ago
  I found several libraries that simply didn't implement the check, but none that implemented in incorrectly in the same way as the vulnerability discussed above. If you didn't receive an email from me, either your implementation isn't listed on https://ianix.com/pub/ed25519-deployment.html https://ianix.com/pub/ed25519-deployment.html, I somehow missed it, or you're safe.
  - F3nd0 10mo ago
    Thank you for your work on free software.
  - pseudohadamard 10mo ago
    [dead]
    - CiPHPerCoder 10mo ago
      > Did you also check all of the libraries that implement the check differently to libsodium? Yes, but it was a breadth-first search sourced from the ianix webpage, so I certainly missed some details somewhere. I'll continue to search over the coming weeks in my spare time (if I can get any).
  - mooreds 9mo ago
    My company just released a JWT library for java that supports Ed25519[0]. Any idea how I can submit that to the ianix list? 0: https://github.com/FusionAuth/fusionauth-jwt https://github.com/FusionAuth/fusionauth-jwt
proof_by_vibes 10mo ago
I've been iterating on sodium bindings in Lean4 for about four months, and now that I've gotten to Ristretto255 I can see why the author is excited about its potential. Ristretto is a tightly designed API that allows me to build arbitrary polynomials on Curve25519 and I've been having a blast tinkering and experimenting with it! If the author by chance reads this, just want to say thank you for your work!
- fshacf 10mo ago
  You have a public repo of this?
  - proof_by_vibes 10mo ago
    Yes: https://github.com/rj-calvin/sodium https://github.com/rj-calvin/sodium The bindings are set and have a monadic interface, but there's some abstractions that still need refining/iterating: mostly I want to be able to formalize keyboard input and eventually build a tactic framework for zero-knowledge proofs.
gafferongames 10mo ago
Such a great library. Thank you Frank Denis
theLiminator 10mo ago
If you work for a big company, consider trying to get Frank sponsored by your company.
- guessmyname 10mo ago
  I work for a big company (Apple) but I have no idea who Frank is, nor how to sponsor them; and even if I knew them and how to sponsor them, the money would come directly from my pocket instead of Apple’s banking account.
  - CiPHPerCoder 10mo ago
    From the article: If libsodium is useful to you, please keep in mind that it is maintained by one person, for free, in time I could spend with my family or on other projects. The best way to help the project would be to consider sponsoring it, which helps me dedicate more time to improving it and making it great for everyone, for many more years to come. The "sponsoring it" links to https://opencollective.com/libsodium/contribute https://opencollective.com/libsodium/contribute Hope that helps.
    - FiloSottile 10mo ago
      Frank does great work that is critical to many businesses, and should get funded to do it professionally. However, donating money to an open collective is prohibitively hard for most big companies. Maybe the world should be different (or maybe not, since it would be easy for employees to embezzle money if they could direct donations easily), but that's how it works currently. AFAICT, there is also no fiscal sponsor, so the donation matching suggested in a sister comment won't apply. This is why Geomys (https://geomys.org https://geomys.org) works the way it does, and why it has revenue (ignoring the FIPS and tlog sides of the business) which is 30-50x of some GitHub Sponsors "success stories": we bill in a way that's compatible with how companies do business, even if effectively we provide a similar service (which is 95% focused on upstream maintenance, not customer support). I am not saying it's for everyone, or that Frank should necessarily adopt this model, or that it's the only way (e.g. the Zig foundation raises real amounts of money, too), but I find it frustrating to see over and over again the same conversation: - "Alice does important maintenance work, she should get professionally funded for it!" - "How does Alice accept/request funding?" - "Monthly credit card transactions anchored at $100/mo that are labeled donations" - no business can move professional amounts of money that way - "Businesses are so short-sighted, it's a tragedy of the commons!"
runtimepanic 10mo ago
Subtle but important bug. This is a good example of how “is valid” checks in crypto are rarely as simple as they sound. Accepting points outside the prime-order subgroup can quietly undermine higher-level assumptions, even if no immediate exploit is obvious. Also a reminder that low-level primitives tend to be reused far more widely than intended, so small validation gaps can have surprisingly large blast radii.
- loup-vaillant 10mo ago
  Do note thought that X25519 and Ed25519 were designed so they wouldn’t need those checks at all. It’s only when you’re trying to design fancier protocols on top of Curve25519 or Edwards25519 that you can run into subgroup issues. And for those use cases, I personally try my best to just reproject everything back into the prime order subgroup whenever possible. Monocypher has a number of such fancy functions: crypto_x25519_dirty_fast() crypto_x25519_dirty_small() crypto_elligator_map() crypto_elligator_rev() crypto_elligator_key_pair() The dirty functions explicitly produce public keys that cover the entire curve, so that random such keys are truly indistinguishable from random when converted with `crypto_elligator_rev()`. But instead of just removing the clamp operation, I instead add random low-order point, so that when we later use the point in an X25519 key exchange, the shared secret is exactly the same as it would have been for a genuine X255119 key. That’s where I thank DJB for designing a key exchange protocol that project the shared secret to the prime order subgroup, even when the public key it processes is not. The original intent may have been to make checks easier (low order keys all end up yielding zero), but a nice side effect is how it enabled a nice API for Mike Hamburg’s Elligator2. > Accepting points outside the prime-order subgroup can quietly undermine higher-level assumptions, even if no immediate exploit is obvious. If on the other hand we can prove that all computed results are low-order-component-independent (as is the case for X25519), then we know for sure we’re safe. In the end, Ristretto is only really needed when we can’t tweak the protocol to safely reproject to the prime order subgroup. Don’t get me wrong, having a prime order group abstraction does help. But if someone is qualified to design a protocol that may require this, they’re qualified to try and make it work with a non-trivial cofactor as well — that, or prove it cannot be done.
greatgib 10mo ago
Libsodium’s goal was to expose APIs to perform operations, not low-level functions. Users shouldn’t even have to know or care about what algorithms are used internally. This is how I’ve always viewed libsodium. ... Over the years, people started using these low-level functions directly. Libsodium started to be used as a toolkit of algorithms and low-level primitives. That is interesting to see the common fallacy of what we think users want versus what they really want. The important point is to be able to recognize that and not coerce users into using your project only how you envisioned it and only like that. Some projects are failure on that count having switched on dictatorial direction on that aspect.
- dwoldrich 10mo ago
  I wrote a C++ implementation of the Framework for Integrated Test (FIT) called CeeFIT, and I was really proud of the way it registered fixtures at compile time. Anyhow, I was surprised that more than one user was using CeeFIT as a sort of batch runner for C++ code, feeding in rows tabular data and executing it against their code. There were a couple bugs I had to fix to support their use cases. I was just happy to have users.
  - sylware 10mo ago
    [flagged]
  - dotancohen 10mo ago
    Some of the most successful products were originally intended for a completely different use case. R7 rockets, Viagra, Hugging Face. The ability to pivot - and to recognize when to pivot - is what makes or breaks.
- baobun 10mo ago
  > The important point is to be able to recognize that and not coerce users into using your project only how you envisioned it and only like that. Some projects are failure on that count having switched on dictatorial direction on that aspect. There is certainly a balance there. If every function inside your code is now considered part of your API contract, almost anything is a breaking change and you can basically forget about ever meaningfully refactoring that codebase. Many times making things private or marking them as internal-only is the right call. I'm not really intimate enough with libsodium to judge if they made the right cut there or not in hindsight.
1vuio0pswjnm7 10mo ago
Is libnacl affected I use software compiled with libnacl every day but none compiled with "libsodium"
1vuio0pswjnm7 9mo ago
https://media.ccc.de/v/39c3-to-sign-or-not-to-sign-practical-vulnerabilities-i https://media.ccc.de/v/39c3-to-sign-or-not-to-sign-practical... "When looking into various PGP-related codebases for some personal use cases, we found these expectations not met, and discovered multiple vulnerabilities in cryptographic utilities, namely in GnuPG, Sequoia PGP, age, and minisign." "The vulnerabilities have implementation bugs at their core, for example in parsing code, rather than bugs in the mathematics of the cryptography itself."

333 points by raggi 10mo ago

This also affected the PHP library, sodium_compat. https://github.com/FriendsOfPHP/security-advisories/pull/756 https://github.com/FriendsOfPHP/security-advisories/pull/756 I'm planning to spend my evening checking every other Ed25519 implementation I can find to see if this check is missing any where else in the open source ecosystem.

hu3 10mo ago
Thank you for your work on open source.
CiPHPerCoder 10mo ago
I found several libraries that simply didn't implement the check, but none that implemented in incorrectly in the same way as the vulnerability discussed above. If you didn't receive an email from me, either your implementation isn't listed on https://ianix.com/pub/ed25519-deployment.html https://ianix.com/pub/ed25519-deployment.html, I somehow missed it, or you're safe.
- F3nd0 10mo ago
  Thank you for your work on free software.
- pseudohadamard 10mo ago
  [dead]
  - CiPHPerCoder 10mo ago
    > Did you also check all of the libraries that implement the check differently to libsodium? Yes, but it was a breadth-first search sourced from the ianix webpage, so I certainly missed some details somewhere. I'll continue to search over the coming weeks in my spare time (if I can get any).
- mooreds 9mo ago
  My company just released a JWT library for java that supports Ed25519[0]. Any idea how I can submit that to the ianix list? 0: https://github.com/FusionAuth/fusionauth-jwt https://github.com/FusionAuth/fusionauth-jwt

proof_by_vibes 10mo ago

I've been iterating on sodium bindings in Lean4 for about four months, and now that I've gotten to Ristretto255 I can see why the author is excited about its potential. Ristretto is a tightly designed API that allows me to build arbitrary polynomials on Curve25519 and I've been having a blast tinkering and experimenting with it! If the author by chance reads this, just want to say thank you for your work!

fshacf 10mo ago
You have a public repo of this?
- proof_by_vibes 10mo ago
  Yes: https://github.com/rj-calvin/sodium https://github.com/rj-calvin/sodium The bindings are set and have a monadic interface, but there's some abstractions that still need refining/iterating: mostly I want to be able to formalize keyboard input and eventually build a tactic framework for zero-knowledge proofs.

gafferongames 10mo ago

Such a great library. Thank you Frank Denis

theLiminator 10mo ago

If you work for a big company, consider trying to get Frank sponsored by your company.

guessmyname 10mo ago
I work for a big company (Apple) but I have no idea who Frank is, nor how to sponsor them; and even if I knew them and how to sponsor them, the money would come directly from my pocket instead of Apple’s banking account.
- CiPHPerCoder 10mo ago
  From the article: If libsodium is useful to you, please keep in mind that it is maintained by one person, for free, in time I could spend with my family or on other projects. The best way to help the project would be to consider sponsoring it, which helps me dedicate more time to improving it and making it great for everyone, for many more years to come. The "sponsoring it" links to https://opencollective.com/libsodium/contribute https://opencollective.com/libsodium/contribute Hope that helps.
  - FiloSottile 10mo ago
    Frank does great work that is critical to many businesses, and should get funded to do it professionally. However, donating money to an open collective is prohibitively hard for most big companies. Maybe the world should be different (or maybe not, since it would be easy for employees to embezzle money if they could direct donations easily), but that's how it works currently. AFAICT, there is also no fiscal sponsor, so the donation matching suggested in a sister comment won't apply. This is why Geomys (https://geomys.org https://geomys.org) works the way it does, and why it has revenue (ignoring the FIPS and tlog sides of the business) which is 30-50x of some GitHub Sponsors "success stories": we bill in a way that's compatible with how companies do business, even if effectively we provide a similar service (which is 95% focused on upstream maintenance, not customer support). I am not saying it's for everyone, or that Frank should necessarily adopt this model, or that it's the only way (e.g. the Zig foundation raises real amounts of money, too), but I find it frustrating to see over and over again the same conversation: - "Alice does important maintenance work, she should get professionally funded for it!" - "How does Alice accept/request funding?" - "Monthly credit card transactions anchored at $100/mo that are labeled donations" - no business can move professional amounts of money that way - "Businesses are so short-sighted, it's a tragedy of the commons!"

runtimepanic 10mo ago

Subtle but important bug. This is a good example of how “is valid” checks in crypto are rarely as simple as they sound. Accepting points outside the prime-order subgroup can quietly undermine higher-level assumptions, even if no immediate exploit is obvious. Also a reminder that low-level primitives tend to be reused far more widely than intended, so small validation gaps can have surprisingly large blast radii.

loup-vaillant 10mo ago
Do note thought that X25519 and Ed25519 were designed so they wouldn’t need those checks at all. It’s only when you’re trying to design fancier protocols on top of Curve25519 or Edwards25519 that you can run into subgroup issues. And for those use cases, I personally try my best to just reproject everything back into the prime order subgroup whenever possible. Monocypher has a number of such fancy functions: crypto_x25519_dirty_fast() crypto_x25519_dirty_small() crypto_elligator_map() crypto_elligator_rev() crypto_elligator_key_pair() The dirty functions explicitly produce public keys that cover the entire curve, so that random such keys are truly indistinguishable from random when converted with `crypto_elligator_rev()`. But instead of just removing the clamp operation, I instead add random low-order point, so that when we later use the point in an X25519 key exchange, the shared secret is exactly the same as it would have been for a genuine X255119 key. That’s where I thank DJB for designing a key exchange protocol that project the shared secret to the prime order subgroup, even when the public key it processes is not. The original intent may have been to make checks easier (low order keys all end up yielding zero), but a nice side effect is how it enabled a nice API for Mike Hamburg’s Elligator2. > Accepting points outside the prime-order subgroup can quietly undermine higher-level assumptions, even if no immediate exploit is obvious. If on the other hand we can prove that all computed results are low-order-component-independent (as is the case for X25519), then we know for sure we’re safe. In the end, Ristretto is only really needed when we can’t tweak the protocol to safely reproject to the prime order subgroup. Don’t get me wrong, having a prime order group abstraction does help. But if someone is qualified to design a protocol that may require this, they’re qualified to try and make it work with a non-trivial cofactor as well — that, or prove it cannot be done.

greatgib 10mo ago

Libsodium’s goal was to expose APIs to perform operations, not low-level functions. Users shouldn’t even have to know or care about what algorithms are used internally. This is how I’ve always viewed libsodium. ... Over the years, people started using these low-level functions directly. Libsodium started to be used as a toolkit of algorithms and low-level primitives. That is interesting to see the common fallacy of what we think users want versus what they really want. The important point is to be able to recognize that and not coerce users into using your project only how you envisioned it and only like that. Some projects are failure on that count having switched on dictatorial direction on that aspect.

dwoldrich 10mo ago
I wrote a C++ implementation of the Framework for Integrated Test (FIT) called CeeFIT, and I was really proud of the way it registered fixtures at compile time. Anyhow, I was surprised that more than one user was using CeeFIT as a sort of batch runner for C++ code, feeding in rows tabular data and executing it against their code. There were a couple bugs I had to fix to support their use cases. I was just happy to have users.
- sylware 10mo ago
  [flagged]
- dotancohen 10mo ago
  Some of the most successful products were originally intended for a completely different use case. R7 rockets, Viagra, Hugging Face. The ability to pivot - and to recognize when to pivot - is what makes or breaks.
baobun 10mo ago
> The important point is to be able to recognize that and not coerce users into using your project only how you envisioned it and only like that. Some projects are failure on that count having switched on dictatorial direction on that aspect. There is certainly a balance there. If every function inside your code is now considered part of your API contract, almost anything is a breaking change and you can basically forget about ever meaningfully refactoring that codebase. Many times making things private or marking them as internal-only is the right call. I'm not really intimate enough with libsodium to judge if they made the right cut there or not in hindsight.

1vuio0pswjnm7 10mo ago

Is libnacl affected I use software compiled with libnacl every day but none compiled with "libsodium"

1vuio0pswjnm7 9mo ago

https://media.ccc.de/v/39c3-to-sign-or-not-to-sign-practical-vulnerabilities-i https://media.ccc.de/v/39c3-to-sign-or-not-to-sign-practical... "When looking into various PGP-related codebases for some personal use cases, we found these expectations not met, and discovered multiple vulnerabilities in cryptographic utilities, namely in GnuPG, Sequoia PGP, age, and minisign." "The vulnerabilities have implementation bugs at their core, for example in parsing code, rather than bugs in the mathematics of the cryptography itself."