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Add Zeroize impl for encoded point and scalar #90

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maurges wants to merge 1 commit into from
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Add Zeroize impl for encoded point and scalar #90

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27 changes: 27 additions & 0 deletions generic-ec/src/encoded.rs
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Original file line number Diff line number Diff line change
@@ -1,8 +1,11 @@
use core::{fmt, ops};

use zeroize::Zeroize;

use crate::{as_raw::AsRaw, core::ByteArray, Curve};

/// Bytes representation of an elliptic point
#[derive(Zeroize)]
pub struct EncodedPoint<E: Curve>(EncodedPointInner<E>);

impl<E: Curve> EncodedPoint<E> {
Expand Down Expand Up @@ -67,6 +70,24 @@ impl<E: Curve> AsRef<[u8]> for EncodedPoint<E> {
}
}

impl<E: Curve> AsMut<[u8]> for EncodedPoint<E> {
fn as_mut(&mut self) -> &mut [u8] {
match &mut self.0 {
EncodedPointInner::Compressed(a) => a.as_mut(),
EncodedPointInner::Uncompressed(a) => a.as_mut(),
}
}
}

impl<E: Curve> Zeroize for EncodedPointInner<E> {
fn zeroize(&mut self) {
match self {
EncodedPointInner::Compressed(a) => a.as_mut().zeroize(),
EncodedPointInner::Uncompressed(a) => a.as_mut().zeroize(),
}
}
}
Comment on lines +82 to +89

@survived survived Jun 15, 2026

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Does it ever happen that an elliptic point represents a sensitive info? I don't recall any such case

@survived survived Jun 15, 2026

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In this case, we would need a SecretPoint<E>...

@maurges maurges Jun 15, 2026

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Yes, like in ECIES or ECDH when a point is fed to KDF - that's a secret info that we want to zeroize

@survived survived Jun 15, 2026

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Right... But I see a little value in adding Zeroize to EncodedPoint, when the point itself is not Zeroize... But making a point Zeroize brings little value without adding SecretPoint...

@survived survived Jun 15, 2026

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Ah the point is Zeroize already! Ok, then let's do Zeroize for EncodedPoint and leave SecretPoint as a thought for the future


/// Bytes representation of a scalar (either in big-endian or in little-endian)
#[derive(Clone)]
pub struct EncodedScalar<E: Curve>(E::ScalarArray);
Expand Down Expand Up @@ -133,3 +154,9 @@ impl<E: Curve> AsRaw for EncodedScalar<E> {
&self.0
}
}

impl<E: Curve> Zeroize for EncodedScalar<E> {
fn zeroize(&mut self) {
self.as_mut().zeroize()
}
}
Comment on lines +158 to +162

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we might wanna add SecretScalar::{to_be_bytes, to_le_bytes} methods that return Zeroizing<Box<EncodedScalar>> (Box cuz otherwise Rust will leave copies of encoded scalar everywhere on the stack)

@maurges maurges Jun 15, 2026

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Interesting idea. Right now I'm thinking about a SecretPoint and it would make a better and safer interface in this case

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