Sentence appears to be cut short

[tcharding]

Multiple places, here is an example.

/// Borrows the global context as a raw pointer and does some operation on it.
///
/// If provided, after the operation is complete, [`rerandomize_global_context`]
/// is called on the context. If you have some random data available,
pub fn with_raw_global_context<T, F: FnOnce(NonNull<ffi::Context>) -> T>(

I don't know what should go here?

[apoelstra]

Oops, this is a little bit subtle. What I mean to say is:

If `rerandomize_seed` is provided, then [`rerandomize_global_context`] is called
on the context after the operation. This argument should be provided alongside
any operation that uses secret data (e.g. signing, but not verification). If you have
random data available, it should be provided here; it will be mixed with the current
random state as well as the system RNG if it is available. If you do not have any
random data, it is fine to provide all zeros, or a counter, or a weak source of entropy.
This is a defense-in-depth measure to protect against side-channel attacks, and
anything helps (and nothing will hurt).

[tcharding]

Cool thanks. IIUC its not mixed, its either data from the provided seed or from rand::rng() but only one of them.

pub fn rerandomize_global_context(seed: &[u8; 32]) {
    SECP256K1.with(|secp| {
        let mut borrow = secp.borrow_mut();

        // If we have access to the thread rng then use it as well.
        #[cfg(feature = "rand")]
        {
            let mut new_seed: [u8; 32] = rand::random();
            for (new, byte) in new_seed.iter_mut().zip(seed.iter()) {
                *new ^= *byte;
            }
            borrow.seeded_randomize(&new_seed);
        }
        #[cfg(not(feature = "rand"))]
        {
            borrow.seeded_randomize(seed);
        }
    });
}

[apoelstra]

The code you cite mixes them with xor.

[tcharding]

If there is an orgy going on in a house and I am to be part of the mix, by standing in the house next door, I would not consider that part of the mix. Right?

[apoelstra]

That image doesn't seem applicable here. If rand is unavailable we use seed directly. If it's available we xor some rand output into it. If there is an orgy, seed is in the room.

[tcharding]

for (new, byte) in new_seed.iter_mut().zip(seed.iter()) {

O.M.G - its like I can't even read code. I never once saw seed hiding in that line. Jee wiz.