opaque-ke 2.0.0

// Copyright (c) Facebook, Inc. and its affiliates.
//
// This source code is licensed under both the MIT license found in the
// LICENSE-MIT file in the root directory of this source tree and the Apache
// License, Version 2.0 found in the LICENSE-APACHE file in the root directory
// of this source tree.

//! Trait specifying a key stretching function

use generic_array::{ArrayLength, GenericArray};

use crate::errors::InternalError;

/// Recommended salt length for argon2-based password hashing.
#[cfg(feature = "argon2")]
const ARGON2_RECOMMENDED_SALT_LEN: usize = 16;

/// Used for the key stretching function in OPAQUE
pub trait Ksf: Default {
    /// Computes the key stretching function
    fn hash<L: ArrayLength<u8>>(
        &self,
        input: GenericArray<u8, L>,
    ) -> Result<GenericArray<u8, L>, InternalError>;
}

/// A no-op hash which simply returns its input
#[derive(Default)]
pub struct Identity;

impl Ksf for Identity {
    fn hash<L: ArrayLength<u8>>(
        &self,
        input: GenericArray<u8, L>,
    ) -> Result<GenericArray<u8, L>, InternalError> {
        Ok(input)
    }
}

#[cfg(feature = "argon2")]
impl Ksf for argon2::Argon2<'_> {
    fn hash<L: ArrayLength<u8>>(
        &self,
        input: GenericArray<u8, L>,
    ) -> Result<GenericArray<u8, L>, InternalError> {
        let mut output = GenericArray::default();
        self.hash_password_into(&input, &[0; ARGON2_RECOMMENDED_SALT_LEN], &mut output)
            .map_err(|_| InternalError::KsfError)?;
        Ok(output)
    }
}