Jędrzej Stuczyński
596bc76cc6
* Updated all non-breaking dependencies * Updated common/crypto dependencies * Updated all tokio [and associated] dependencies to most recent version * Bumped version of rand_distr * Fixed api changes in tests * Made clippy happier about the acronym * Fixed the type while trying to make clippy even happier * nightly cargo fmt
69 lines
2.7 KiB
Rust
69 lines
2.7 KiB
Rust
// Copyright 2020 Nym Technologies SA
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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use crate::asymmetric::encryption;
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use crate::hkdf;
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use cipher::stream::{Key, NewStreamCipher, SyncStreamCipher};
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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, Key<C>)
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where
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C: SyncStreamCipher + NewStreamCipher,
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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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Key::<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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) -> Key<C>
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where
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C: SyncStreamCipher + NewStreamCipher,
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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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Key::<C>::from_exact_iter(okm).expect("okm was expanded to incorrect length!")
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}
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