Vulnerabilities

RUSTSEC-2024-0344

Timing variability in curve25519-dalek's Scalar29::sub/Scalar52::sub

Timing variability of any kind is problematic when working with potentially secret values such as
elliptic curve scalars, and such issues can potentially leak private keys and other secrets. Such a
problem was recently discovered in curve25519-dalek.

The Scalar29::sub (32-bit) and Scalar52::sub (64-bit) functions contained usage of a mask value
inside a loop where LLVM saw an opportunity to insert a branch instruction (jns on x86) to
conditionally bypass this code section when the mask value is set to zero as can be seen in godbolt:

• 32-bit (see L106): <https://godbolt.org/z/zvaWxzvqv>
• 64-bit (see L48): <https://godbolt.org/z/PczYj7Pda>

A similar problem was recently discovered in the Kyber reference implementation:

<https://groups.google.com/a/list.nist.gov/g/pqc-forum/c/hqbtIGFKIpU/m/cnE3pbueBgAJ>

As discussed on that thread, one portable solution, which is also used in this PR, is to introduce a
volatile read as an optimization barrier, which prevents the compiler from optimizing it away.

The fix can be validated in godbolt here:

• 32-bit: <https://godbolt.org/z/jc9j7eb8E>
• 64-bit: <https://godbolt.org/z/x8d46Yfah>

The problem was discovered and the solution independently verified by
Alexander Wagner <[email protected]> and Lea Themint <[email protected]> using
their DATA tool:

<https://github.com/Fraunhofer-AISEC/DATA>

Warnings

RUSTSEC-2021-0139

ansi_term is Unmaintained

The maintainer has advised that this crate is deprecated and will not receive any maintenance.

The crate does not seem to have much dependencies and may or may not be ok to use as-is.

Last release seems to have been three years ago.

Possible Alternative(s)

The below list has not been vetted in any way and may or may not contain alternatives;

• ansiterm
• anstyle
• console
• nu-ansi-term
• owo-colors
• stylish
• yansi

Dependency Specific Migration(s)

• structopt, clap2

RUSTSEC-2021-0065

anymap is unmaintained.

The anymap crate does not appear to be maintained, and the most recent
published version 0.12.1 includes a soundness bug. This has been
fixed a few years ago, but
was never released.

RUSTSEC-2021-0141

dotenv is Unmaintained

dotenv by description is meant to be used in development or testing only.

Using this in production may or may not be advisable.

Alternatives

The below may or may not be feasible alternative(s):

• dotenvy