digest: remove VariableOutput trait

digest/CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## 0.11.0 (UNRELEASED)
 ### Added
 - `CustomizedInit` trait ([#1334])
+- `VariableOutputCoreCustomized` trait ([#1787], [#2043])
 - `buffer_fixed`, `buffer_ct_variable`, `buffer_rt_variable`, and `buffer_xof` macros ([#1799])
 - `CollisionResistance` trait ([#1820])
 
@@ -24,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `CoreWrapper`, `RtVariableCoreWrapper`, and `XofReaderCoreWrapper` types ([#1799])
 - `HashReader` and `HashWriter` are moved to the `digest-io` crate ([#1809])
 - `io::Write/Read` implementations in favor of the `digest_io::IoWrapper` type ([#1809])
+- `VariableOutput` trait ([#2043])
 
 [#1173]: https://github.com/RustCrypto/traits/pull/1173
 [#1334]: https://github.com/RustCrypto/traits/pull/1334
@@ -33,6 +35,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [#1820]: https://github.com/RustCrypto/traits/pull/1820
 [#1953]: https://github.com/RustCrypto/traits/pull/1953
 [#1958]: https://github.com/RustCrypto/traits/pull/1958
+[#2043]: https://github.com/RustCrypto/traits/pull/2043
 
 ## 0.10.7 (2023-05-19)
 ### Changed

digest/src/block_api.rs

@@ -113,6 +113,12 @@ pub trait VariableOutputCore: UpdateCore + OutputSizeUser + BufferKindUser + Siz
     fn finalize_variable_core(&mut self, buffer: &mut Buffer<Self>, out: &mut Output<Self>);
 }
 
+/// Trait adding customization string to hash functions with variable output.
+pub trait VariableOutputCoreCustomized: VariableOutputCore {
+    /// Create new hasher instance with the given customization string and output size.
+    fn new_customized(customization: &[u8], output_size: usize) -> Self;
+}
+
 /// Type which used for defining truncation side in the [`VariableOutputCore`]
 /// trait.
 #[derive(Copy, Clone, Debug)]

digest/src/block_api/ct_variable.rs

@@ -1,10 +1,10 @@
 use super::{
     AlgorithmName, Buffer, BufferKindUser, FixedOutputCore, Reset, TruncSide, UpdateCore,
-    VariableOutputCore,
+    VariableOutputCore, VariableOutputCoreCustomized,
 };
 #[cfg(feature = "mac")]
 use crate::MacMarker;
-use crate::{CollisionResistance, CustomizedInit, HashMarker, VarOutputCustomized};
+use crate::{CollisionResistance, CustomizedInit, HashMarker};
 use core::{fmt, marker::PhantomData};
 use crypto_common::{
     Block, BlockSizeUser, OutputSizeUser,
@@ -120,7 +120,7 @@ where
 
 impl<T, OutSize> CustomizedInit for CtOutWrapper<T, OutSize>
 where
-    T: VariableOutputCore + VarOutputCustomized,
+    T: VariableOutputCoreCustomized,
     OutSize: ArraySize + IsLessOrEqual<T::OutputSize, Output = True>,
 {
     #[inline]

digest/src/buffer_macros.rs

@@ -1,4 +1,3 @@
 mod fixed;
-mod variable_ct;
-mod variable_rt;
+mod variable;
 mod xof;

digest/src/dev.rs

@@ -6,13 +6,11 @@ mod fixed;
 #[cfg(feature = "mac")]
 mod mac;
 mod rng;
-mod variable;
 mod xof;
 
 pub use fixed::*;
 #[cfg(feature = "mac")]
 pub use mac::*;
-pub use variable::*;
 pub use xof::*;
 
 /// Test vector for hash functions

digest/src/lib.rs

@@ -6,10 +6,9 @@
 //! - **High-level convenience traits**: [`Digest`], [`DynDigest`], [`Mac`].
 //!   Wrappers around lower-level traits for most common use-cases. Users should
 //!   usually prefer using these traits.
-//! - **Mid-level traits**: [`Update`], [`FixedOutput`], [`FixedOutputReset`],
-//!   [`ExtendableOutput`], [`ExtendableOutputReset`], [`XofReader`],
-//!   [`VariableOutput`], [`Reset`], [`KeyInit`], and [`InnerInit`]. These
-//!   traits atomically describe available functionality of an algorithm.
+//! - **Mid-level traits**: [`Update`], [`FixedOutput`], [`FixedOutputReset`], [`ExtendableOutput`],
+//!   [`ExtendableOutputReset`], [`XofReader`], [`Reset`], [`KeyInit`], and [`InnerInit`].
+//!   These traits atomically describe available functionality of an algorithm.
 //! - **Marker traits**: [`HashMarker`], [`MacMarker`]. Used to distinguish
 //!   different algorithm classes.
 //! - **Low-level traits** defined in the [`block_api`] module. These traits
@@ -207,90 +206,12 @@ pub trait ExtendableOutputReset: ExtendableOutput + Reset {
     }
 }
 
-/// Trait for hash functions with variable-size output.
-pub trait VariableOutput: Sized + Update {
-    /// Maximum size of output hash in bytes.
-    const MAX_OUTPUT_SIZE: usize;
-
-    /// Create new hasher instance with the given output size in bytes.
-    ///
-    /// It will return `Err(InvalidOutputSize)` in case if hasher can not return
-    /// hash of the specified output size.
-    fn new(output_size: usize) -> Result<Self, InvalidOutputSize>;
-
-    /// Get output size in bytes of the hasher instance provided to the `new` method
-    fn output_size(&self) -> usize;
-
-    /// Write result into the output buffer.
-    ///
-    /// Returns `Err(InvalidOutputSize)` if `out` size is not equal to
-    /// `self.output_size()`.
-    fn finalize_variable(self, out: &mut [u8]) -> Result<(), InvalidBufferSize>;
-
-    /// Compute hash of `data` and write it to `output`.
-    ///
-    /// Length of the output hash is determined by `output`. If `output` is
-    /// bigger than `Self::MAX_OUTPUT_SIZE`, this method returns
-    /// `InvalidOutputSize`.
-    fn digest_variable(
-        input: impl AsRef<[u8]>,
-        output: &mut [u8],
-    ) -> Result<(), InvalidOutputSize> {
-        let mut hasher = Self::new(output.len())?;
-        hasher.update(input.as_ref());
-        hasher
-            .finalize_variable(output)
-            .map_err(|_| InvalidOutputSize)
-    }
-
-    /// Retrieve result into a boxed slice and consume hasher.
-    ///
-    /// `Box<[u8]>` is used instead of `Vec<u8>` to save stack space, since
-    /// they have size of 2 and 3 words respectively.
-    #[cfg(feature = "alloc")]
-    fn finalize_boxed(self) -> Box<[u8]> {
-        let n = self.output_size();
-        let mut buf = vec![0u8; n].into_boxed_slice();
-        self.finalize_variable(&mut buf)
-            .expect("buf length is equal to output_size");
-        buf
-    }
-}
-
-/// Trait for hash functions with variable-size output able to reset themselves.
-pub trait VariableOutputReset: VariableOutput + Reset {
-    /// Write result into the output buffer and reset the hasher state.
-    ///
-    /// Returns `Err(InvalidOutputSize)` if `out` size is not equal to
-    /// `self.output_size()`.
-    fn finalize_variable_reset(&mut self, out: &mut [u8]) -> Result<(), InvalidBufferSize>;
-
-    /// Retrieve result into a boxed slice and reset the hasher state.
-    ///
-    /// `Box<[u8]>` is used instead of `Vec<u8>` to save stack space, since
-    /// they have size of 2 and 3 words respectively.
-    #[cfg(feature = "alloc")]
-    fn finalize_boxed_reset(&mut self) -> Box<[u8]> {
-        let n = self.output_size();
-        let mut buf = vec![0u8; n].into_boxed_slice();
-        self.finalize_variable_reset(&mut buf)
-            .expect("buf length is equal to output_size");
-        buf
-    }
-}
-
 /// Trait for hash functions with customization string for domain separation.
 pub trait CustomizedInit: Sized {
     /// Create new hasher instance with the given customization string.
     fn new_customized(customization: &[u8]) -> Self;
 }
 
-/// Trait adding customization string to hash functions with variable output.
-pub trait VarOutputCustomized: Sized {
-    /// Create new hasher instance with the given customization string and output size.
-    fn new_customized(customization: &[u8], output_size: usize) -> Self;
-}
-
 /// Types with a certain collision resistance.
 pub trait CollisionResistance {
     /// Collision resistance in bytes. This applies to an output size of `CollisionResistance * 2`.