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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*!
* The mac module defines the Message Authentication Code (Mac) trait.
*/
use util::fixed_time_eq;
/**
* The Mac trait defines methods for a Message Authentication function.
*/
pub trait Mac {
/**
* Process input data.
*
* # Arguments
* * data - The input data to process.
*
*/
fn input(&mut self, data: &[u8]);
/**
* Reset the Mac state to begin processing another input stream.
*/
fn reset(&mut self);
/**
* Obtain the result of a Mac computation as a MacResult.
*/
fn result(&mut self) -> MacResult;
/**
* Obtain the result of a Mac computation as [u8]. This method should be used very carefully
* since incorrect use of the Mac code could result in permitting a timing attack which defeats
* the security provided by a Mac function.
*/
fn raw_result(&mut self, output: &mut [u8]);
/**
* Get the size of the Mac code, in bytes.
*/
fn output_bytes(&self) -> usize;
}
/**
* A MacResult wraps a Mac code and provides a safe Eq implementation that runs in fixed time.
*/
pub struct MacResult {
code: Vec<u8>
}
impl MacResult {
/**
* Create a new MacResult.
*/
pub fn new(code: &[u8]) -> MacResult {
MacResult {
code: code.to_vec()
}
}
/**
* Create a new MacResult taking ownership of the specified code value.
*/
pub fn new_from_owned(code: Vec<u8>) -> MacResult {
MacResult {
code: code
}
}
/**
* Get the code value. Be very careful using this method, since incorrect use of the code value
* may permit timing attacks which defeat the security provided by the Mac function.
*/
pub fn code<'s>(&'s self) -> &'s [u8] {
&self.code[..]
}
}
impl PartialEq for MacResult {
fn eq(&self, x: &MacResult) -> bool {
let lhs = self.code();
let rhs = x.code();
fixed_time_eq(lhs, rhs)
}
}
impl Eq for MacResult { }