Jędrzej Stuczyński
827c13b69e
dont build netstack in CI additional rust 2024 fixes fixes removed temp.rs first round of cleanup removed duplicated NS types moved gateway probe to the monorepo
66 lines
2.4 KiB
Rust
66 lines
2.4 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::x25519;
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use crate::hkdf;
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use cipher::{Key, KeyIvInit, StreamCipher};
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use digest::Digest;
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use digest::crypto_common::BlockSizeUser;
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#[cfg(feature = "rand")]
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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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#[cfg(feature = "rand")]
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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: &x25519::PublicKey,
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) -> (x25519::KeyPair, Key<C>)
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where
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C: StreamCipher + KeyIvInit,
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D: Digest + BlockSizeUser + Clone,
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R: RngCore + CryptoRng,
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{
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let ephemeral_keypair = x25519::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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// SAFETY: while this is a relatively weak assumption, it's unlikely that any stream cipher has `C::key_size()`
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// larger than 255 * chunk_size of the digest (so for example keys larger than 8160 bytes if sh256 is used)
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#[allow(clippy::expect_used)]
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let okm = hkdf::extract_then_expand::<D>(None, &dh_result, None, C::key_size())
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.expect("somehow too long okm was provided");
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// SAFETY: the generated okm has exactly `C::key_size()` elements,
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// so this call is safe
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#[allow(clippy::unwrap_used)]
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let derived_shared_key = Key::<C>::from_exact_iter(okm).unwrap();
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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: &x25519::PublicKey,
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local_key: &x25519::PrivateKey,
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) -> Key<C>
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where
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C: StreamCipher + KeyIvInit,
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D: Digest + BlockSizeUser + Clone,
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{
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let dh_result = local_key.diffie_hellman(remote_key);
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// SAFETY: while this is a relatively weak assumption, it's unlikely that any stream cipher has `C::key_size()`
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// larger than 255 * chunk_size of the digest (so for example keys larger than 8160 bytes if sh256 is used)
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#[allow(clippy::expect_used)]
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let okm = hkdf::extract_then_expand::<D>(None, &dh_result, None, C::key_size())
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.expect("somehow too long okm was provided");
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// SAFETY: the generated okm has exactly `C::key_size()` elements,
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// so this call is safe
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#[allow(clippy::unwrap_used)]
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Key::<C>::from_exact_iter(okm).unwrap()
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}
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