Simon Wicky
69 lines
1.9 KiB
Rust
69 lines
1.9 KiB
Rust
// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
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// SPDX-License-Identifier: Apache-2.0
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use thiserror::Error;
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#[derive(Default, Clone, Copy, Debug, PartialEq, Eq)]
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#[repr(u8)]
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pub enum SphinxKeyRotation {
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// for legacy packets, where there's no explicit information which key has been used
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#[default]
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Unknown = 0,
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OddRotation = 1,
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EvenRotation = 2,
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}
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impl SphinxKeyRotation {
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pub fn from_key_rotation_id(rotation_id: u32) -> Self {
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rotation_id.into()
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}
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pub fn is_unknown(&self) -> bool {
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matches!(self, SphinxKeyRotation::Unknown)
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}
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pub fn is_even(&self) -> bool {
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matches!(self, SphinxKeyRotation::EvenRotation)
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}
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pub fn is_odd(&self) -> bool {
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matches!(self, SphinxKeyRotation::OddRotation)
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}
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}
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#[derive(Debug, Error)]
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#[error("{received} is not a valid encoding of a sphinx key rotation")]
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pub struct InvalidSphinxKeyRotation {
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received: u8,
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}
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// convert from particular rotation id into SphinxKeyRotation variant
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impl From<u32> for SphinxKeyRotation {
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fn from(value: u32) -> Self {
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if value == 0 || value == u32::MAX {
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SphinxKeyRotation::Unknown
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} else if value.is_multiple_of(2) {
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SphinxKeyRotation::EvenRotation
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} else {
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SphinxKeyRotation::OddRotation
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}
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}
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}
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// convert from an encoded SphinxKeyRotation into particular variant
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// if value is actually provided, it MUST be one of the two. otherwise is invalid
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impl TryFrom<u8> for SphinxKeyRotation {
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type Error = InvalidSphinxKeyRotation;
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fn try_from(value: u8) -> Result<Self, Self::Error> {
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match value {
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_ if value == (Self::Unknown as u8) => Ok(Self::Unknown),
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_ if value == (Self::OddRotation as u8) => Ok(Self::OddRotation),
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_ if value == (Self::EvenRotation as u8) => Ok(Self::EvenRotation),
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received => Err(InvalidSphinxKeyRotation { received }),
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}
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}
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}
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