Drazen Urch
5dfaff6296
* Update hmac and blake3 * Remain paranoid for `0.*` crates * Most paranoid versions :) * Updated aes and using published version of blake3 Co-authored-by: Jędrzej Stuczyński <jedrzej.stuczynski@gmail.com>
58 lines
2.2 KiB
Rust
58 lines
2.2 KiB
Rust
// Copyright 2021 - Nym Technologies SA <contact@nymtech.net>
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// SPDX-License-Identifier: Apache-2.0
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use crate::asymmetric::encryption;
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use crate::hkdf;
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use cipher::{CipherKey, NewCipher, StreamCipher};
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use digest::{BlockInput, FixedOutput, Reset, Update};
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use generic_array::{typenum::Unsigned, ArrayLength};
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use rand::{CryptoRng, RngCore};
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/// Generate an ephemeral encryption keypair and perform diffie-hellman to establish
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/// shared key with the remote.
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pub fn new_ephemeral_shared_key<C, D, R>(
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rng: &mut R,
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remote_key: &encryption::PublicKey,
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) -> (encryption::KeyPair, CipherKey<C>)
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where
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C: StreamCipher + NewCipher,
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D: Update + BlockInput + FixedOutput + Reset + Default + Clone,
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D::BlockSize: ArrayLength<u8>,
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D::OutputSize: ArrayLength<u8>,
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R: RngCore + CryptoRng,
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{
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let ephemeral_keypair = encryption::KeyPair::new(rng);
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// after performing diffie-hellman we don't care about the private component anymore
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let dh_result = ephemeral_keypair.private_key().diffie_hellman(remote_key);
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// there is no reason for this to fail as our okm is expected to be only C::KeySize bytes
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let okm = hkdf::extract_then_expand::<D>(None, &dh_result, None, C::KeySize::to_usize())
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.expect("somehow too long okm was provided");
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let derived_shared_key =
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CipherKey::<C>::from_exact_iter(okm).expect("okm was expanded to incorrect length!");
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(ephemeral_keypair, derived_shared_key)
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}
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/// Recompute shared key using remote public key and local private key.
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pub fn recompute_shared_key<C, D>(
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remote_key: &encryption::PublicKey,
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local_key: &encryption::PrivateKey,
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) -> CipherKey<C>
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where
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C: StreamCipher + NewCipher,
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D: Update + BlockInput + FixedOutput + Reset + Default + Clone,
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D::BlockSize: ArrayLength<u8>,
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D::OutputSize: ArrayLength<u8>,
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{
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let dh_result = local_key.diffie_hellman(remote_key);
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// there is no reason for this to fail as our okm is expected to be only C::KeySize bytes
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let okm = hkdf::extract_then_expand::<D>(None, &dh_result, None, C::KeySize::to_usize())
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.expect("somehow too long okm was provided");
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CipherKey::<C>::from_exact_iter(okm).expect("okm was expanded to incorrect length!")
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}
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