Adding upstream version 0.70.1+ds1.upstream/0.70.1+ds1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 405 insertions, 0 deletions

diff --git a/vendor/elliptic-curve/src/scalar/nonzero.rs b/vendor/elliptic-curve/src/scalar/nonzero.rs
new file mode 100644
index 0000000..c0e4574
--- /dev/null
+++ b/vendor/elliptic-curve/src/scalar/nonzero.rs
@@ -0,0 +1,405 @@
+//! Non-zero scalar type.
+
+use crate::{
+    ops::{Invert, Reduce, ReduceNonZero},
+    scalar::IsHigh,
+    CurveArithmetic, Error, FieldBytes, PrimeCurve, Scalar, ScalarPrimitive, SecretKey,
+};
+use base16ct::HexDisplay;
+use core::{
+    fmt,
+    ops::{Deref, Mul, Neg},
+    str,
+};
+use crypto_bigint::{ArrayEncoding, Integer};
+use ff::{Field, PrimeField};
+use generic_array::{typenum::Unsigned, GenericArray};
+use rand_core::CryptoRngCore;
+use subtle::{Choice, ConditionallySelectable, ConstantTimeEq, CtOption};
+use zeroize::Zeroize;
+
+#[cfg(feature = "serde")]
+use serdect::serde::{de, ser, Deserialize, Serialize};
+
+/// Non-zero scalar type.
+///
+/// This type ensures that its value is not zero, ala `core::num::NonZero*`.
+/// To do this, the generic `S` type must impl both `Default` and
+/// `ConstantTimeEq`, with the requirement that `S::default()` returns 0.
+///
+/// In the context of ECC, it's useful for ensuring that scalar multiplication
+/// cannot result in the point at infinity.
+#[derive(Clone)]
+pub struct NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    scalar: Scalar<C>,
+}
+
+impl<C> NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    /// Generate a random `NonZeroScalar`.
+    pub fn random(mut rng: &mut impl CryptoRngCore) -> Self {
+        // Use rejection sampling to eliminate zero values.
+        // While this method isn't constant-time, the attacker shouldn't learn
+        // anything about unrelated outputs so long as `rng` is a secure `CryptoRng`.
+        loop {
+            if let Some(result) = Self::new(Field::random(&mut rng)).into() {
+                break result;
+            }
+        }
+    }
+
+    /// Create a [`NonZeroScalar`] from a scalar.
+    pub fn new(scalar: Scalar<C>) -> CtOption<Self> {
+        CtOption::new(Self { scalar }, !scalar.is_zero())
+    }
+
+    /// Decode a [`NonZeroScalar`] from a big endian-serialized field element.
+    pub fn from_repr(repr: FieldBytes<C>) -> CtOption<Self> {
+        Scalar::<C>::from_repr(repr).and_then(Self::new)
+    }
+
+    /// Create a [`NonZeroScalar`] from a `C::Uint`.
+    pub fn from_uint(uint: C::Uint) -> CtOption<Self> {
+        ScalarPrimitive::new(uint).and_then(|scalar| Self::new(scalar.into()))
+    }
+}
+
+impl<C> AsRef<Scalar<C>> for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn as_ref(&self) -> &Scalar<C> {
+        &self.scalar
+    }
+}
+
+impl<C> ConditionallySelectable for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
+        Self {
+            scalar: Scalar::<C>::conditional_select(&a.scalar, &b.scalar, choice),
+        }
+    }
+}
+
+impl<C> ConstantTimeEq for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn ct_eq(&self, other: &Self) -> Choice {
+        self.scalar.ct_eq(&other.scalar)
+    }
+}
+
+impl<C> Copy for NonZeroScalar<C> where C: CurveArithmetic {}
+
+impl<C> Deref for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    type Target = Scalar<C>;
+
+    fn deref(&self) -> &Scalar<C> {
+        &self.scalar
+    }
+}
+
+impl<C> From<NonZeroScalar<C>> for FieldBytes<C>
+where
+    C: CurveArithmetic,
+{
+    fn from(scalar: NonZeroScalar<C>) -> FieldBytes<C> {
+        Self::from(&scalar)
+    }
+}
+
+impl<C> From<&NonZeroScalar<C>> for FieldBytes<C>
+where
+    C: CurveArithmetic,
+{
+    fn from(scalar: &NonZeroScalar<C>) -> FieldBytes<C> {
+        scalar.to_repr()
+    }
+}
+
+impl<C> From<NonZeroScalar<C>> for ScalarPrimitive<C>
+where
+    C: CurveArithmetic,
+{
+    #[inline]
+    fn from(scalar: NonZeroScalar<C>) -> ScalarPrimitive<C> {
+        Self::from(&scalar)
+    }
+}
+
+impl<C> From<&NonZeroScalar<C>> for ScalarPrimitive<C>
+where
+    C: CurveArithmetic,
+{
+    fn from(scalar: &NonZeroScalar<C>) -> ScalarPrimitive<C> {
+        ScalarPrimitive::from_bytes(&scalar.to_repr()).unwrap()
+    }
+}
+
+impl<C> From<SecretKey<C>> for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn from(sk: SecretKey<C>) -> NonZeroScalar<C> {
+        Self::from(&sk)
+    }
+}
+
+impl<C> From<&SecretKey<C>> for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn from(sk: &SecretKey<C>) -> NonZeroScalar<C> {
+        let scalar = sk.as_scalar_primitive().to_scalar();
+        debug_assert!(!bool::from(scalar.is_zero()));
+        Self { scalar }
+    }
+}
+
+impl<C> Invert for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+    Scalar<C>: Invert<Output = CtOption<Scalar<C>>>,
+{
+    type Output = Self;
+
+    fn invert(&self) -> Self {
+        Self {
+            // This will always succeed since `scalar` will never be 0
+            scalar: Invert::invert(&self.scalar).unwrap(),
+        }
+    }
+
+    fn invert_vartime(&self) -> Self::Output {
+        Self {
+            // This will always succeed since `scalar` will never be 0
+            scalar: Invert::invert_vartime(&self.scalar).unwrap(),
+        }
+    }
+}
+
+impl<C> IsHigh for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn is_high(&self) -> Choice {
+        self.scalar.is_high()
+    }
+}
+
+impl<C> Neg for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    type Output = NonZeroScalar<C>;
+
+    fn neg(self) -> NonZeroScalar<C> {
+        let scalar = -self.scalar;
+        debug_assert!(!bool::from(scalar.is_zero()));
+        NonZeroScalar { scalar }
+    }
+}
+
+impl<C> Mul<NonZeroScalar<C>> for NonZeroScalar<C>
+where
+    C: PrimeCurve + CurveArithmetic,
+{
+    type Output = Self;
+
+    #[inline]
+    fn mul(self, other: Self) -> Self {
+        Self::mul(self, &other)
+    }
+}
+
+impl<C> Mul<&NonZeroScalar<C>> for NonZeroScalar<C>
+where
+    C: PrimeCurve + CurveArithmetic,
+{
+    type Output = Self;
+
+    fn mul(self, other: &Self) -> Self {
+        // Multiplication is modulo a prime, so the product of two non-zero
+        // scalars is also non-zero.
+        let scalar = self.scalar * other.scalar;
+        debug_assert!(!bool::from(scalar.is_zero()));
+        NonZeroScalar { scalar }
+    }
+}
+
+/// Note: this is a non-zero reduction, as it's impl'd for [`NonZeroScalar`].
+impl<C, I> Reduce<I> for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+    I: Integer + ArrayEncoding,
+    Scalar<C>: Reduce<I> + ReduceNonZero<I>,
+{
+    type Bytes = <Scalar<C> as Reduce<I>>::Bytes;
+
+    fn reduce(n: I) -> Self {
+        let scalar = Scalar::<C>::reduce_nonzero(n);
+        debug_assert!(!bool::from(scalar.is_zero()));
+        Self { scalar }
+    }
+
+    fn reduce_bytes(bytes: &Self::Bytes) -> Self {
+        let scalar = Scalar::<C>::reduce_nonzero_bytes(bytes);
+        debug_assert!(!bool::from(scalar.is_zero()));
+        Self { scalar }
+    }
+}
+
+/// Note: forwards to the [`Reduce`] impl.
+impl<C, I> ReduceNonZero<I> for NonZeroScalar<C>
+where
+    Self: Reduce<I>,
+    C: CurveArithmetic,
+    I: Integer + ArrayEncoding,
+    Scalar<C>: Reduce<I, Bytes = Self::Bytes> + ReduceNonZero<I>,
+{
+    fn reduce_nonzero(n: I) -> Self {
+        Self::reduce(n)
+    }
+
+    fn reduce_nonzero_bytes(bytes: &Self::Bytes) -> Self {
+        Self::reduce_bytes(bytes)
+    }
+}
+
+impl<C> TryFrom<&[u8]> for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    type Error = Error;
+
+    fn try_from(bytes: &[u8]) -> Result<Self, Error> {
+        if bytes.len() == C::FieldBytesSize::USIZE {
+            Option::from(NonZeroScalar::from_repr(GenericArray::clone_from_slice(
+                bytes,
+            )))
+            .ok_or(Error)
+        } else {
+            Err(Error)
+        }
+    }
+}
+
+impl<C> Zeroize for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn zeroize(&mut self) {
+        // Use zeroize's volatile writes to ensure value is cleared.
+        self.scalar.zeroize();
+
+        // Write a 1 instead of a 0 to ensure this type's non-zero invariant
+        // is upheld.
+        self.scalar = Scalar::<C>::ONE;
+    }
+}
+
+impl<C> fmt::Display for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{self:X}")
+    }
+}
+
+impl<C> fmt::LowerHex for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:x}", HexDisplay(&self.to_repr()))
+    }
+}
+
+impl<C> fmt::UpperHex for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:}", HexDisplay(&self.to_repr()))
+    }
+}
+
+impl<C> str::FromStr for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    type Err = Error;
+
+    fn from_str(hex: &str) -> Result<Self, Error> {
+        let mut bytes = FieldBytes::<C>::default();
+
+        if base16ct::mixed::decode(hex, &mut bytes)?.len() == bytes.len() {
+            Option::from(Self::from_repr(bytes)).ok_or(Error)
+        } else {
+            Err(Error)
+        }
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<C> Serialize for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: ser::Serializer,
+    {
+        ScalarPrimitive::from(self).serialize(serializer)
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de, C> Deserialize<'de> for NonZeroScalar<C>
+where
+    C: CurveArithmetic,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: de::Deserializer<'de>,
+    {
+        let scalar = ScalarPrimitive::deserialize(deserializer)?;
+        Option::from(Self::new(scalar.into()))
+            .ok_or_else(|| de::Error::custom("expected non-zero scalar"))
+    }
+}
+
+#[cfg(all(test, feature = "dev"))]
+mod tests {
+    use crate::dev::{NonZeroScalar, Scalar};
+    use ff::{Field, PrimeField};
+    use hex_literal::hex;
+    use zeroize::Zeroize;
+
+    #[test]
+    fn round_trip() {
+        let bytes = hex!("c9afa9d845ba75166b5c215767b1d6934e50c3db36e89b127b8a622b120f6721");
+        let scalar = NonZeroScalar::from_repr(bytes.into()).unwrap();
+        assert_eq!(&bytes, scalar.to_repr().as_slice());
+    }
+
+    #[test]
+    fn zeroize() {
+        let mut scalar = NonZeroScalar::new(Scalar::from(42u64)).unwrap();
+        scalar.zeroize();
+        assert_eq!(*scalar, Scalar::ONE);
+    }
+}