Jędrzej Stuczyński
49ce56c367
* introduced PacketVersion into FramedSphinxPacket * Using legacy mode by default in mixnodes and gateways * fixed unit tests
76 lines
3.4 KiB
Rust
76 lines
3.4 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 crypto::aes::Aes128;
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use crypto::blake3;
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use crypto::ctr;
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type Aes128Ctr = ctr::Ctr64BE<Aes128>;
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// Re-export for ease of use
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pub use packet_modes::PacketMode;
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pub use packet_sizes::PacketSize;
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pub mod packet_modes;
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pub mod packet_sizes;
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pub mod packet_version;
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// If somebody can provide an argument why it might be reasonable to have more than 255 mix hops,
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// I will change this to [`usize`]
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pub const DEFAULT_NUM_MIX_HOPS: u8 = 3;
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// TODO: not entirely sure how to feel about those being defined here, ideally it'd be where [`Fragment`]
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// is defined, but that'd introduce circular dependencies as the acknowledgements crate also needs
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// access to that
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pub const FRAG_ID_LEN: usize = 5;
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pub type SerializedFragmentIdentifier = [u8; FRAG_ID_LEN];
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// wait, wait, but why are we starting with version 7?
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// when packet header gets serialized, the following bytes (in that order) are put onto the wire:
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// - packet_version (starting with v1.1.0)
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// - packet_size indicator
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// - packet_mode
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// it also just so happens that the only valid values for packet_size indicator include values 1-6
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// therefore if we receive byte `7` (or larger than that) we'll know we received a versioned packet,
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// otherwise we should treat it as legacy
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/// Increment it whenever we perform any breaking change in the wire format!
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const CURRENT_PACKET_VERSION_NUMBER: u8 = 7;
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// TODO: ask @AP about the choice of below algorithms
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/// Hashing algorithm used during hkdf for ephemeral shared key generation per sphinx packet payload.
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pub type PacketHkdfAlgorithm = blake3::Hasher;
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/// Hashing algorithm used during hkdf while establishing long-term shared key between client and gateway.
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pub type GatewaySharedKeyHkdfAlgorithm = blake3::Hasher;
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/// Hashing algorithm used when computing digest of a reply SURB encryption key.
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pub type ReplySurbKeyDigestAlgorithm = blake3::Hasher;
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/// Hashing algorithm used when computing integrity (H)Mac for message exchanged between client and gateway.
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// TODO: if updated, the pem type defined in gateway\gateway-requests\src\registration\handshake\shared_key
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// needs updating!
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pub type GatewayIntegrityHmacAlgorithm = blake3::Hasher;
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/// Encryption algorithm used for encrypting acknowledgement messages.
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// TODO: if updated:
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// - PacketSize::ACK_PACKET_SIZE needs to be manually updated (if nonce/iv size differs);
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// this requirement will eventually go away once const generics are stabilised (and generic_array and co. start using them)
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// - the pem type defined in nym\common\nymsphinx\acknowledgements\src\key needs updating!
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pub type AckEncryptionAlgorithm = Aes128Ctr;
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/// Encryption algorithm used for end-to-end encryption of messages exchanged between clients
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/// and their gateways.
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// TODO: if updated, the pem type defined in gateway\gateway-requests\src\registration\handshake\shared_key
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// needs updating!
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pub type GatewayEncryptionAlgorithm = Aes128Ctr;
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/// Encryption algorithm used for end-to-end encryption of messages exchanged between clients that are
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/// encapsulated inside sphinx packets.
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pub type PacketEncryptionAlgorithm = Aes128Ctr;
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/// Encryption algorithm used for end-to-end encryption of reply messages constructed using ReplySURBs.
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// TODO: I don't see any reason for it to be different than what is used for regular packets. Perhaps
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// it could be potentially insecure to use anything else?
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pub type ReplySurbEncryptionAlgorithm = PacketEncryptionAlgorithm;
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