opaque-vx 1.0.0-rc.0

An implementation of the OPAQUE password-authenticated key exchange protocol
Documentation 
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// SPDX-License-Identifier: MIT OR Apache-2.0
// Copyright (c) VexaHub and contributors.
// Copyright (c) Meta Platforms, Inc. and affiliates.

//! Trait specifying a key stretching function

use generic_array::{ArrayLength, GenericArray};

use crate::errors::InternalError;

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

#[cfg(feature = "argon2")]
impl Ksf for argon2::Argon2<'_> {
    fn hash<L: ArrayLength>(
        &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)
    }
}