Jon Häggblad
59 lines
1.6 KiB
Rust
59 lines
1.6 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::AckKey;
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use nym_crypto::symmetric::stream_cipher::{self, encrypt, iv_from_slice, random_iv, IvSizeUser};
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use nym_sphinx_params::{AckEncryptionAlgorithm, SerializedFragmentIdentifier, FRAG_ID_LEN};
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use rand::{CryptoRng, RngCore};
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// TODO: should those functions even exist in this file?
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pub fn prepare_identifier<R: RngCore + CryptoRng>(
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rng: &mut R,
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key: &AckKey,
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serialized_id: SerializedFragmentIdentifier,
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) -> Vec<u8> {
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let iv = random_iv::<AckEncryptionAlgorithm, _>(rng);
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let id_ciphertext = encrypt::<AckEncryptionAlgorithm>(key.inner(), &iv, &serialized_id);
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// IV || ID_CIPHERTEXT
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iv.into_iter().chain(id_ciphertext).collect()
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}
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pub fn recover_identifier(
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key: &AckKey,
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iv_id_ciphertext: &[u8],
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) -> Option<SerializedFragmentIdentifier> {
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let iv_size = AckEncryptionAlgorithm::iv_size();
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let iv = iv_from_slice::<AckEncryptionAlgorithm>(&iv_id_ciphertext[..iv_size]);
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let id = stream_cipher::decrypt::<AckEncryptionAlgorithm>(
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key.inner(),
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iv,
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&iv_id_ciphertext[iv_size..],
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);
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let mut id_arr = [0u8; FRAG_ID_LEN];
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id_arr.copy_from_slice(&id);
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Some(id_arr)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use rand::rngs::OsRng;
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#[test]
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fn id_is_recoverable() {
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let mut rng = OsRng;
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let key = AckKey::new(&mut rng);
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let id = [1, 2, 3, 4, 5];
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let iv_ciphertext = prepare_identifier(&mut rng, &key, id);
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assert_eq!(
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id.to_vec(),
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recover_identifier(&key, &iv_ciphertext).unwrap()
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);
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}
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}
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