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digest.rs
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digest.rs
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use super::{FixedOutput, Reset, Update};
use generic_array::typenum::Unsigned;
use generic_array::{ArrayLength, GenericArray};
/// The `Digest` trait specifies an interface common for digest functions.
///
/// It's a convenience wrapper around [`Update`], [`FixedOutput`], [`Reset`],
/// [`Clone`], and [`Default`] traits. It also provides additional convenience methods.
pub trait Digest {
/// Output size for `Digest`
type OutputSize: ArrayLength<u8>;
/// Create new hasher instance
fn new() -> Self;
/// Digest data, updating the internal state.
///
/// This method can be called repeatedly for use with streaming messages.
fn update(&mut self, data: impl AsRef<[u8]>);
/// Digest input data in a chained manner.
fn chain(self, data: impl AsRef<[u8]>) -> Self
where
Self: Sized;
/// Retrieve result and consume hasher instance.
fn finalize(self) -> Output<Self>;
/// Retrieve result and reset hasher instance.
///
/// This method sometimes can be more efficient compared to hasher
/// re-creation.
fn finalize_reset(&mut self) -> Output<Self>;
/// Reset hasher instance to its initial state.
fn reset(&mut self);
/// Get output size of the hasher
fn output_size() -> usize;
/// Convenience function to compute hash of the `data`. It will handle
/// hasher creation, data feeding and finalization.
///
/// Example:
///
/// ```rust,ignore
/// println!("{:x}", sha2::Sha256::digest(b"Hello world"));
/// ```
fn digest(data: &[u8]) -> Output<Self>;
}
impl<D: Update + FixedOutput + Reset + Clone + Default> Digest for D {
type OutputSize = <Self as FixedOutput>::OutputSize;
fn new() -> Self {
Self::default()
}
fn update(&mut self, data: impl AsRef<[u8]>) {
Update::update(self, data);
}
fn chain(self, data: impl AsRef<[u8]>) -> Self
where
Self: Sized,
{
Update::chain(self, data)
}
fn finalize(self) -> Output<Self> {
self.finalize_fixed()
}
fn finalize_reset(&mut self) -> Output<Self> {
let res = self.clone().finalize_fixed();
self.reset();
res
}
fn reset(&mut self) {
<Self as Reset>::reset(self)
}
fn output_size() -> usize {
Self::OutputSize::to_usize()
}
fn digest(data: &[u8]) -> Output<Self> {
let mut hasher = Self::default();
Update::update(&mut hasher, data);
hasher.finalize_fixed()
}
}
/// Output of a [`Digest`] function
pub type Output<D> = GenericArray<u8, <D as Digest>::OutputSize>;