Vendor things

third-party/vendor/digest/src/mac.rs

@@ -0,0 +1,305 @@
+use crate::{FixedOutput, FixedOutputReset, Update};
+use crypto_common::{InvalidLength, Key, KeyInit, Output, OutputSizeUser, Reset};
+
+#[cfg(feature = "rand_core")]
+use crate::rand_core::{CryptoRng, RngCore};
+use core::fmt;
+use crypto_common::typenum::Unsigned;
+use subtle::{Choice, ConstantTimeEq};
+
+/// Marker trait for Message Authentication algorithms.
+#[cfg_attr(docsrs, doc(cfg(feature = "mac")))]
+pub trait MacMarker {}
+
+/// Convenience wrapper trait covering functionality of Message Authentication algorithms.
+///
+/// This trait wraps [`KeyInit`], [`Update`], [`FixedOutput`], and [`MacMarker`]
+/// traits and provides additional convenience methods.
+#[cfg_attr(docsrs, doc(cfg(feature = "mac")))]
+pub trait Mac: OutputSizeUser + Sized {
+    /// Create new value from fixed size key.
+    fn new(key: &Key<Self>) -> Self
+    where
+        Self: KeyInit;
+
+    /// Generate random key using the provided [`CryptoRng`].
+    #[cfg(feature = "rand_core")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rand_core")))]
+    fn generate_key(rng: impl CryptoRng + RngCore) -> Key<Self>
+    where
+        Self: KeyInit;
+
+    /// Create new value from variable size key.
+    fn new_from_slice(key: &[u8]) -> Result<Self, InvalidLength>
+    where
+        Self: KeyInit;
+
+    /// Update state using the provided data.
+    fn update(&mut self, data: &[u8]);
+
+    /// Process input data in a chained manner.
+    #[must_use]
+    fn chain_update(self, data: impl AsRef<[u8]>) -> Self;
+
+    /// Obtain the result of a [`Mac`] computation as a [`CtOutput`] and consume
+    /// [`Mac`] instance.
+    fn finalize(self) -> CtOutput<Self>;
+
+    /// Obtain the result of a [`Mac`] computation as a [`CtOutput`] and reset
+    /// [`Mac`] instance.
+    fn finalize_reset(&mut self) -> CtOutput<Self>
+    where
+        Self: FixedOutputReset;
+
+    /// Reset MAC instance to its initial state.
+    fn reset(&mut self)
+    where
+        Self: Reset;
+
+    /// Check if tag/code value is correct for the processed input.
+    fn verify(self, tag: &Output<Self>) -> Result<(), MacError>;
+
+    /// Check if tag/code value is correct for the processed input and reset
+    /// [`Mac`] instance.
+    fn verify_reset(&mut self, tag: &Output<Self>) -> Result<(), MacError>
+    where
+        Self: FixedOutputReset;
+
+    /// Check truncated tag correctness using all bytes
+    /// of calculated tag.
+    ///
+    /// Returns `Error` if `tag` is not valid or not equal in length
+    /// to MAC's output.
+    fn verify_slice(self, tag: &[u8]) -> Result<(), MacError>;
+
+    /// Check truncated tag correctness using all bytes
+    /// of calculated tag and reset [`Mac`] instance.
+    ///
+    /// Returns `Error` if `tag` is not valid or not equal in length
+    /// to MAC's output.
+    fn verify_slice_reset(&mut self, tag: &[u8]) -> Result<(), MacError>
+    where
+        Self: FixedOutputReset;
+
+    /// Check truncated tag correctness using left side bytes
+    /// (i.e. `tag[..n]`) of calculated tag.
+    ///
+    /// Returns `Error` if `tag` is not valid or empty.
+    fn verify_truncated_left(self, tag: &[u8]) -> Result<(), MacError>;
+
+    /// Check truncated tag correctness using right side bytes
+    /// (i.e. `tag[n..]`) of calculated tag.
+    ///
+    /// Returns `Error` if `tag` is not valid or empty.
+    fn verify_truncated_right(self, tag: &[u8]) -> Result<(), MacError>;
+}
+
+impl<T: Update + FixedOutput + MacMarker> Mac for T {
+    #[inline(always)]
+    fn new(key: &Key<Self>) -> Self
+    where
+        Self: KeyInit,
+    {
+        KeyInit::new(key)
+    }
+
+    #[inline(always)]
+    fn new_from_slice(key: &[u8]) -> Result<Self, InvalidLength>
+    where
+        Self: KeyInit,
+    {
+        KeyInit::new_from_slice(key)
+    }
+
+    #[inline]
+    fn update(&mut self, data: &[u8]) {
+        Update::update(self, data);
+    }
+
+    #[inline]
+    fn chain_update(mut self, data: impl AsRef<[u8]>) -> Self {
+        Update::update(&mut self, data.as_ref());
+        self
+    }
+
+    #[inline]
+    fn finalize(self) -> CtOutput<Self> {
+        CtOutput::new(self.finalize_fixed())
+    }
+
+    #[inline(always)]
+    fn finalize_reset(&mut self) -> CtOutput<Self>
+    where
+        Self: FixedOutputReset,
+    {
+        CtOutput::new(self.finalize_fixed_reset())
+    }
+
+    #[inline]
+    fn reset(&mut self)
+    where
+        Self: Reset,
+    {
+        Reset::reset(self)
+    }
+
+    #[inline]
+    fn verify(self, tag: &Output<Self>) -> Result<(), MacError> {
+        if self.finalize() == tag.into() {
+            Ok(())
+        } else {
+            Err(MacError)
+        }
+    }
+
+    #[inline]
+    fn verify_reset(&mut self, tag: &Output<Self>) -> Result<(), MacError>
+    where
+        Self: FixedOutputReset,
+    {
+        if self.finalize_reset() == tag.into() {
+            Ok(())
+        } else {
+            Err(MacError)
+        }
+    }
+
+    #[inline]
+    fn verify_slice(self, tag: &[u8]) -> Result<(), MacError> {
+        let n = tag.len();
+        if n != Self::OutputSize::USIZE {
+            return Err(MacError);
+        }
+        let choice = self.finalize_fixed().ct_eq(tag);
+        if choice.into() {
+            Ok(())
+        } else {
+            Err(MacError)
+        }
+    }
+
+    #[inline]
+    fn verify_slice_reset(&mut self, tag: &[u8]) -> Result<(), MacError>
+    where
+        Self: FixedOutputReset,
+    {
+        let n = tag.len();
+        if n != Self::OutputSize::USIZE {
+            return Err(MacError);
+        }
+        let choice = self.finalize_fixed_reset().ct_eq(tag);
+        if choice.into() {
+            Ok(())
+        } else {
+            Err(MacError)
+        }
+    }
+
+    fn verify_truncated_left(self, tag: &[u8]) -> Result<(), MacError> {
+        let n = tag.len();
+        if n == 0 || n > Self::OutputSize::USIZE {
+            return Err(MacError);
+        }
+        let choice = self.finalize_fixed()[..n].ct_eq(tag);
+
+        if choice.into() {
+            Ok(())
+        } else {
+            Err(MacError)
+        }
+    }
+
+    fn verify_truncated_right(self, tag: &[u8]) -> Result<(), MacError> {
+        let n = tag.len();
+        if n == 0 || n > Self::OutputSize::USIZE {
+            return Err(MacError);
+        }
+        let m = Self::OutputSize::USIZE - n;
+        let choice = self.finalize_fixed()[m..].ct_eq(tag);
+
+        if choice.into() {
+            Ok(())
+        } else {
+            Err(MacError)
+        }
+    }
+
+    #[cfg(feature = "rand_core")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rand_core")))]
+    #[inline]
+    fn generate_key(rng: impl CryptoRng + RngCore) -> Key<Self>
+    where
+        Self: KeyInit,
+    {
+        <T as KeyInit>::generate_key(rng)
+    }
+}
+
+/// Fixed size output value which provides a safe [`Eq`] implementation that
+/// runs in constant time.
+///
+/// It is useful for implementing Message Authentication Codes (MACs).
+#[derive(Clone)]
+#[cfg_attr(docsrs, doc(cfg(feature = "mac")))]
+pub struct CtOutput<T: OutputSizeUser> {
+    bytes: Output<T>,
+}
+
+impl<T: OutputSizeUser> CtOutput<T> {
+    /// Create a new [`CtOutput`] value.
+    #[inline(always)]
+    pub fn new(bytes: Output<T>) -> Self {
+        Self { bytes }
+    }
+
+    /// Get the inner [`Output`] array this type wraps.
+    #[inline(always)]
+    pub fn into_bytes(self) -> Output<T> {
+        self.bytes
+    }
+}
+
+impl<T: OutputSizeUser> From<Output<T>> for CtOutput<T> {
+    #[inline(always)]
+    fn from(bytes: Output<T>) -> Self {
+        Self { bytes }
+    }
+}
+
+impl<'a, T: OutputSizeUser> From<&'a Output<T>> for CtOutput<T> {
+    #[inline(always)]
+    fn from(bytes: &'a Output<T>) -> Self {
+        bytes.clone().into()
+    }
+}
+
+impl<T: OutputSizeUser> ConstantTimeEq for CtOutput<T> {
+    #[inline(always)]
+    fn ct_eq(&self, other: &Self) -> Choice {
+        self.bytes.ct_eq(&other.bytes)
+    }
+}
+
+impl<T: OutputSizeUser> PartialEq for CtOutput<T> {
+    #[inline(always)]
+    fn eq(&self, x: &CtOutput<T>) -> bool {
+        self.ct_eq(x).into()
+    }
+}
+
+impl<T: OutputSizeUser> Eq for CtOutput<T> {}
+
+/// Error type for when the [`Output`] of a [`Mac`]
+/// is not equal to the expected value.
+#[derive(Default, Debug, Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(docsrs, doc(cfg(feature = "mac")))]
+pub struct MacError;
+
+impl fmt::Display for MacError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("MAC tag mismatch")
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for MacError {}