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//! Relay cell cryptography
//!
//! The Tor protocol centers around "RELAY cells", which are transmitted through
//! the network along circuits. The client that creates a circuit shares two
//! different sets of keys and state with each of the relays on the circuit: one
//! for "outbound" traffic, and one for "inbound" traffic.
//!
//! So for example, if a client creates a 3-hop circuit with relays R1, R2, and
//! R3, the client has:
//! * An "inbound" cryptographic state shared with R1.
//! * An "inbound" cryptographic state shared with R2.
//! * An "inbound" cryptographic state shared with R3.
//! * An "outbound" cryptographic state shared with R1.
//! * An "outbound" cryptographic state shared with R2.
//! * An "outbound" cryptographic state shared with R3.
//!
//! In this module at least, we'll call each of these state objects a "layer" of
//! the circuit's encryption.
//!
//! The Tor specification does not describe these layer objects very explicitly.
//! In the current relay cryptography protocol, each layer contains:
//! * A keyed AES-CTR state. (AES-128 or AES-256) This cipher uses a key
//! called `Kf` or `Kb` in the spec, where `Kf` is a "forward" key used in
//! the outbound direction, and `Kb` is a "backward" key used in the
//! inbound direction.
//! * A running digest. (SHA1 or SHA3) This digest is initialized with a
//! value called `Df` or `Db` in the spec.
//!
//! This `crypto::cell` module itself provides traits and implementations that
//! should work for all current future versions of the relay cell crypto design.
//! The current Tor protocols are instantiated in a `tor1` submodule.
use crate::{Error, Result};
use tor_cell::chancell::BoxedCellBody;
use tor_error::internal;
use digest::generic_array::GenericArray;
use super::binding::CircuitBinding;
/// Type for the body of a relay cell.
#[derive(Clone, derive_more::From, derive_more::Into)]
pub(crate) struct RelayCellBody(BoxedCellBody);
impl AsRef<[u8]> for RelayCellBody {
fn as_ref(&self) -> &[u8] {
&self.0[..]
}
}
impl AsMut<[u8]> for RelayCellBody {
fn as_mut(&mut self) -> &mut [u8] {
&mut self.0[..]
}
}
/// Represents the ability for one hop of a circuit's cryptographic state to be
/// initialized from a given seed.
pub(crate) trait CryptInit: Sized {
/// Return the number of bytes that this state will require.
fn seed_len() -> usize;
/// Construct this state from a seed of the appropriate length.
fn initialize(seed: &[u8]) -> Result<Self>;
/// Initialize this object from a key generator.
fn construct<K: super::handshake::KeyGenerator>(keygen: K) -> Result<Self> {
let seed = keygen.expand(Self::seed_len())?;
Self::initialize(&seed[..])
}
}
/// A paired object containing the inbound and outbound cryptographic layers
/// used by a client to communicate with a single hop on one of its circuits.
///
/// TODO: Maybe we should fold this into CryptInit.
pub(crate) trait ClientLayer<F, B>
where
F: OutboundClientLayer,
B: InboundClientLayer,
{
/// Consume this ClientLayer and return a paired forward and reverse
/// crypto layer, and a [`CircuitBinding`] object
fn split(self) -> (F, B, CircuitBinding);
}
/// Represents a relay's view of the crypto state on a given circuit.
#[allow(dead_code)] // TODO #1383 ????
pub(crate) trait RelayCrypt {
/// Prepare a RelayCellBody to be sent towards the client.
fn originate(&mut self, cell: &mut RelayCellBody);
/// Encrypt a RelayCellBody that is moving towards the client.
fn encrypt_inbound(&mut self, cell: &mut RelayCellBody);
/// Decrypt a RelayCellBody that is moving towards the client.
///
/// Return true if it is addressed to us.
fn decrypt_outbound(&mut self, cell: &mut RelayCellBody) -> bool;
}
/// A client's view of the cryptographic state shared with a single relay on a
/// circuit, as used for outbound cells.
pub(crate) trait OutboundClientLayer {
/// Prepare a RelayCellBody to be sent to the relay at this layer, and
/// encrypt it.
///
/// Return the authentication tag.
fn originate_for(&mut self, cell: &mut RelayCellBody) -> &[u8];
/// Encrypt a RelayCellBody to be decrypted by this layer.
fn encrypt_outbound(&mut self, cell: &mut RelayCellBody);
}
/// A client's view of the crypto state shared with a single relay on a circuit,
/// as used for inbound cells.
pub(crate) trait InboundClientLayer {
/// Decrypt a CellBody that passed through this layer.
///
/// Return an authentication tag if this layer is the originator.
fn decrypt_inbound(&mut self, cell: &mut RelayCellBody) -> Option<&[u8]>;
}
/// Type to store hop indices on a circuit.
///
/// Hop indices are zero-based: "0" denotes the first hop on the circuit.
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
pub struct HopNum(u8);
impl HopNum {
/// Return an object that implements [`Display`](std::fmt::Display) for printing `HopNum`s.
///
/// This will display the `HopNum` as a 1-indexed value (the string representation of the first
/// hop is `"#1"`).
///
/// To display the zero-based underlying representation of the `HopNum`, use
/// [`Debug`](std::fmt::Debug).
pub fn display(&self) -> HopNumDisplay {
HopNumDisplay(*self)
}
}
/// A helper for displaying [`HopNum`]s.
///
/// The [`Display`](std::fmt::Display) of this type displays the `HopNum` as a 1-based index
/// prefixed with the number sign (`#`). For example, the string representation of the first hop is
/// `"#1"`.
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
pub struct HopNumDisplay(HopNum);
impl std::fmt::Display for HopNumDisplay {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> {
let hop_num: u8 = self.0.into();
write!(f, "#{}", hop_num + 1)
}
}
impl From<HopNum> for u8 {
fn from(hop: HopNum) -> u8 {
hop.0
}
}
impl From<u8> for HopNum {
fn from(v: u8) -> HopNum {
HopNum(v)
}
}
impl From<HopNum> for usize {
fn from(hop: HopNum) -> usize {
hop.0 as usize
}
}
/// A client's view of the cryptographic state for an entire
/// constructed circuit, as used for sending cells.
pub(crate) struct OutboundClientCrypt {
/// Vector of layers, one for each hop on the circuit, ordered from the
/// closest hop to the farthest.
layers: Vec<Box<dyn OutboundClientLayer + Send>>,
}
/// A client's view of the cryptographic state for an entire
/// constructed circuit, as used for receiving cells.
pub(crate) struct InboundClientCrypt {
/// Vector of layers, one for each hop on the circuit, ordered from the
/// closest hop to the farthest.
layers: Vec<Box<dyn InboundClientLayer + Send>>,
}
/// The length of the tag that we include (with this algorithm) in an
/// authenticated SENDME message.
const SENDME_TAG_LEN: usize = 20;
impl OutboundClientCrypt {
/// Return a new (empty) OutboundClientCrypt.
pub(crate) fn new() -> Self {
OutboundClientCrypt { layers: Vec::new() }
}
/// Prepare a cell body to sent away from the client.
///
/// The cell is prepared for the `hop`th hop, and then encrypted with
/// the appropriate keys.
///
/// On success, returns a reference to tag that should be expected
/// for an authenticated SENDME sent in response to this cell.
pub(crate) fn encrypt(
&mut self,
cell: &mut RelayCellBody,
hop: HopNum,
) -> Result<&[u8; SENDME_TAG_LEN]> {
let hop: usize = hop.into();
if hop >= self.layers.len() {
return Err(Error::NoSuchHop);
}
let mut layers = self.layers.iter_mut().take(hop + 1).rev();
let first_layer = layers.next().ok_or(Error::NoSuchHop)?;
let tag = first_layer.originate_for(cell);
for layer in layers {
layer.encrypt_outbound(cell);
}
Ok(tag.try_into().expect("wrong SENDME digest size"))
}
/// Add a new layer to this OutboundClientCrypt
pub(crate) fn add_layer(&mut self, layer: Box<dyn OutboundClientLayer + Send>) {
assert!(self.layers.len() < u8::MAX as usize);
self.layers.push(layer);
}
/// Return the number of layers configured on this OutboundClientCrypt.
pub(crate) fn n_layers(&self) -> usize {
self.layers.len()
}
}
impl InboundClientCrypt {
/// Return a new (empty) InboundClientCrypt.
pub(crate) fn new() -> Self {
InboundClientCrypt { layers: Vec::new() }
}
/// Decrypt an incoming cell that is coming to the client.
///
/// On success, return which hop was the originator of the cell.
// TODO(nickm): Use a real type for the tag, not just `&[u8]`.
pub(crate) fn decrypt(&mut self, cell: &mut RelayCellBody) -> Result<(HopNum, &[u8])> {
for (hopnum, layer) in self.layers.iter_mut().enumerate() {
if let Some(tag) = layer.decrypt_inbound(cell) {
let hopnum = HopNum(u8::try_from(hopnum).expect("Somehow > 255 hops"));
return Ok((hopnum, tag));
}
}
Err(Error::BadCellAuth)
}
/// Add a new layer to this InboundClientCrypt
pub(crate) fn add_layer(&mut self, layer: Box<dyn InboundClientLayer + Send>) {
assert!(self.layers.len() < u8::MAX as usize);
self.layers.push(layer);
}
/// Return the number of layers configured on this InboundClientCrypt.
///
/// TODO: use HopNum
#[allow(dead_code)]
pub(crate) fn n_layers(&self) -> usize {
self.layers.len()
}
}
/// Standard Tor relay crypto, as instantiated for RELAY cells.
pub(crate) type Tor1RelayCrypto<RCF> =
tor1::CryptStatePair<tor_llcrypto::cipher::aes::Aes128Ctr, tor_llcrypto::d::Sha1, RCF>;
/// Standard Tor relay crypto, as instantiated for the HSv3 protocol.
///
/// (The use of SHA3 is ridiculously overkill.)
#[cfg(feature = "hs-common")]
pub(crate) type Tor1Hsv3RelayCrypto<RCF> =
tor1::CryptStatePair<tor_llcrypto::cipher::aes::Aes256Ctr, tor_llcrypto::d::Sha3_256, RCF>;
/// An implementation of Tor's current relay cell cryptography.
///
/// These are not very good algorithms; they were the best we could come up with
/// in ~2002. They are somewhat inefficient, and vulnerable to tagging attacks.
/// They should get replaced within the next several years. For information on
/// some older proposed alternatives so far, see proposals 261, 295, and 298.
///
/// I am calling this design `tor1`; it does not have a generally recognized
/// name.
pub(crate) mod tor1 {
use std::marker::PhantomData;
use crate::crypto::binding::CIRC_BINDING_LEN;
use super::*;
use cipher::{KeyIvInit, StreamCipher};
use digest::Digest;
use tor_cell::relaycell::{RelayCellFields, RelayCellFormatTrait};
use typenum::Unsigned;
/// A CryptState represents one layer of shared cryptographic state between
/// a relay and a client for a single hop, in a single direction.
///
/// For example, if a client makes a 3-hop circuit, then it will have 6
/// `CryptState`s, one for each relay, for each direction of communication.
///
/// Note that although `CryptState` implements [`OutboundClientLayer`],
/// [`InboundClientLayer`], and [`RelayCrypt`], any single `CryptState`
/// instance will only be used for one of these roles.
///
/// It is parameterized on a stream cipher and a digest type: most circuits
/// will use AES-128-CTR and SHA1, but v3 onion services use AES-256-CTR and
/// SHA-3.
pub(crate) struct CryptState<SC: StreamCipher, D: Digest + Clone, RCF: RelayCellFormatTrait> {
/// Stream cipher for en/decrypting cell bodies.
///
/// This cipher is the one keyed with Kf or Kb in the spec.
cipher: SC,
/// Digest for authenticating cells to/from this hop.
///
/// This digest is the one keyed with Df or Db in the spec.
digest: D,
/// Most recent digest value generated by this crypto.
last_digest_val: GenericArray<u8, D::OutputSize>,
/// The format used for relay cells at this layer.
relay_cell_format: PhantomData<RCF>,
}
/// A pair of CryptStates shared between a client and a relay, one for the
/// outbound (away from the client) direction, and one for the inbound
/// (towards the client) direction.
pub(crate) struct CryptStatePair<SC: StreamCipher, D: Digest + Clone, RCF: RelayCellFormatTrait> {
/// State for en/decrypting cells sent away from the client.
fwd: CryptState<SC, D, RCF>,
/// State for en/decrypting cells sent towards the client.
back: CryptState<SC, D, RCF>,
/// A circuit binding key.
binding: CircuitBinding,
}
impl<SC: StreamCipher + KeyIvInit, D: Digest + Clone, RCF: RelayCellFormatTrait> CryptInit
for CryptStatePair<SC, D, RCF>
{
fn seed_len() -> usize {
SC::KeySize::to_usize() * 2 + D::OutputSize::to_usize() * 2 + CIRC_BINDING_LEN
}
fn initialize(mut seed: &[u8]) -> Result<Self> {
// This corresponds to the use of the KDF algorithm as described in
// tor-spec 5.2.2
if seed.len() != Self::seed_len() {
return Err(Error::from(internal!(
"seed length {} was invalid",
seed.len()
)));
}
// Advances `seed` by `n` bytes, returning the advanced bytes
let mut take_seed = |n: usize| -> &[u8] {
let res = &seed[..n];
seed = &seed[n..];
res
};
let dlen = D::OutputSize::to_usize();
let keylen = SC::KeySize::to_usize();
let df = take_seed(dlen);
let db = take_seed(dlen);
let kf = take_seed(keylen);
let kb = take_seed(keylen);
let binding_key = take_seed(CIRC_BINDING_LEN);
let fwd = CryptState {
cipher: SC::new(kf.into(), &Default::default()),
digest: D::new().chain_update(df),
last_digest_val: GenericArray::default(),
relay_cell_format: PhantomData,
};
let back = CryptState {
cipher: SC::new(kb.into(), &Default::default()),
digest: D::new().chain_update(db),
last_digest_val: GenericArray::default(),
relay_cell_format: PhantomData,
};
let binding = CircuitBinding::try_from(binding_key)?;
Ok(CryptStatePair { fwd, back, binding })
}
}
impl<SC, D, RCF> ClientLayer<CryptState<SC, D, RCF>, CryptState<SC, D, RCF>>
for CryptStatePair<SC, D, RCF>
where
SC: StreamCipher,
D: Digest + Clone,
RCF: RelayCellFormatTrait,
{
fn split(
self,
) -> (
CryptState<SC, D, RCF>,
CryptState<SC, D, RCF>,
CircuitBinding,
) {
(self.fwd, self.back, self.binding)
}
}
impl<SC: StreamCipher, D: Digest + Clone, RCF: RelayCellFormatTrait> RelayCrypt
for CryptStatePair<SC, D, RCF>
{
fn originate(&mut self, cell: &mut RelayCellBody) {
let mut d_ignored = GenericArray::default();
cell.set_digest::<_, RCF>(&mut self.back.digest, &mut d_ignored);
}
fn encrypt_inbound(&mut self, cell: &mut RelayCellBody) {
// This is describe in tor-spec 5.5.3.1, "Relaying Backward at Onion Routers"
self.back.cipher.apply_keystream(cell.as_mut());
}
fn decrypt_outbound(&mut self, cell: &mut RelayCellBody) -> bool {
// This is describe in tor-spec 5.5.2.2, "Relaying Forward at Onion Routers"
self.fwd.cipher.apply_keystream(cell.as_mut());
let mut d_ignored = GenericArray::default();
cell.is_recognized::<_, RCF>(&mut self.fwd.digest, &mut d_ignored)
}
}
impl<SC: StreamCipher, D: Digest + Clone, RCF: RelayCellFormatTrait> OutboundClientLayer
for CryptState<SC, D, RCF>
{
fn originate_for(&mut self, cell: &mut RelayCellBody) -> &[u8] {
cell.set_digest::<_, RCF>(&mut self.digest, &mut self.last_digest_val);
self.encrypt_outbound(cell);
// Note that we truncate the authentication tag here if we are using
// a digest with a more-than-20-byte length.
&self.last_digest_val[..SENDME_TAG_LEN]
}
fn encrypt_outbound(&mut self, cell: &mut RelayCellBody) {
// This is a single iteration of the loop described in tor-spec
// 5.5.2.1, "routing away from the origin."
self.cipher.apply_keystream(&mut cell.0[..]);
}
}
impl<SC: StreamCipher, D: Digest + Clone, RCF: RelayCellFormatTrait> InboundClientLayer
for CryptState<SC, D, RCF>
{
fn decrypt_inbound(&mut self, cell: &mut RelayCellBody) -> Option<&[u8]> {
// This is a single iteration of the loop described in tor-spec
// 5.5.3, "routing to the origin."
self.cipher.apply_keystream(&mut cell.0[..]);
if cell.is_recognized::<_, RCF>(&mut self.digest, &mut self.last_digest_val) {
Some(&self.last_digest_val[..SENDME_TAG_LEN])
} else {
None
}
}
}
/// Functions on RelayCellBody that implement the digest/recognized
/// algorithm.
///
/// The current relay crypto protocol uses two wholly inadequate fields to
/// see whether a cell is intended for its current recipient: a two-byte
/// "recognized" field that needs to be all-zero; and a four-byte "digest"
/// field containing a running digest of all cells (for this recipient) to
/// this one, seeded with an initial value (either Df or Db in the spec).
///
/// These operations is described in tor-spec section 6.1 "Relay cells"
impl RelayCellBody {
/// Returns the byte slice of the `recognized` field.
fn recognized<RCF: RelayCellFormatTrait>(&self) -> &[u8] {
&self.0[RCF::FIELDS::RECOGNIZED_RANGE]
}
/// Returns the mut byte slice of the `recognized` field.
fn recognized_mut<RCF: RelayCellFormatTrait>(&mut self) -> &mut [u8] {
&mut self.0[RCF::FIELDS::RECOGNIZED_RANGE]
}
/// Returns the byte slice of the `digest` field.
fn digest<RCF: RelayCellFormatTrait>(&self) -> &[u8] {
&self.0[RCF::FIELDS::DIGEST_RANGE]
}
/// Returns the mut byte slice of the `digest` field.
fn digest_mut<RCF: RelayCellFormatTrait>(&mut self) -> &mut [u8] {
&mut self.0[RCF::FIELDS::DIGEST_RANGE]
}
/// Prepare a cell body by setting its digest and recognized field.
fn set_digest<D: Digest + Clone, RCF: RelayCellFormatTrait>(
&mut self,
d: &mut D,
used_digest: &mut GenericArray<u8, D::OutputSize>,
) {
self.recognized_mut::<RCF>().fill(0); // Set 'Recognized' to zero
self.digest_mut::<RCF>().fill(0); // Set Digest to zero
d.update(&self.0[..]);
// TODO(nickm) can we avoid this clone? Probably not.
*used_digest = d.clone().finalize();
let used_digest_prefix = &used_digest[0..RCF::FIELDS::DIGEST_RANGE.len()];
self.digest_mut::<RCF>().copy_from_slice(used_digest_prefix);
}
/// Check whether this just-decrypted cell is now an authenticated plaintext.
///
/// This method returns true if the `recognized` field is all zeros, and if the
/// `digest` field is a digest of the correct material.
///
/// If this method returns false, then either further decryption is required,
/// or the cell is corrupt.
// TODO #1336: Further optimize and/or benchmark this.
fn is_recognized<D: Digest + Clone, RCF: RelayCellFormatTrait>(
&self,
d: &mut D,
rcvd: &mut GenericArray<u8, D::OutputSize>,
) -> bool {
use crate::util::ct;
// Validate 'Recognized' field
if !ct::is_zero(self.recognized::<RCF>()) {
return false;
}
// Now also validate the 'Digest' field:
let mut dtmp = d.clone();
// Add bytes up to the 'Digest' field
dtmp.update(&self.0[..RCF::FIELDS::DIGEST_RANGE.start]);
// Add zeroes where the 'Digest' field is
dtmp.update(RCF::FIELDS::EMPTY_DIGEST);
// Add the rest of the bytes
dtmp.update(&self.0[RCF::FIELDS::DIGEST_RANGE.end..]);
// Clone the digest before finalize destroys it because we will use
// it in the future
let dtmp_clone = dtmp.clone();
let result = dtmp.finalize();
if ct::bytes_eq(
self.digest::<RCF>(),
&result[0..RCF::FIELDS::DIGEST_RANGE.len()],
) {
// Copy useful things out of this cell (we keep running digest)
*d = dtmp_clone;
*rcvd = result;
return true;
}
false
}
}
}
#[cfg(test)]
mod test {
// @@ begin test lint list maintained by maint/add_warning @@
#![allow(clippy::bool_assert_comparison)]
#![allow(clippy::clone_on_copy)]
#![allow(clippy::dbg_macro)]
#![allow(clippy::mixed_attributes_style)]
#![allow(clippy::print_stderr)]
#![allow(clippy::print_stdout)]
#![allow(clippy::single_char_pattern)]
#![allow(clippy::unwrap_used)]
#![allow(clippy::unchecked_duration_subtraction)]
#![allow(clippy::useless_vec)]
#![allow(clippy::needless_pass_by_value)]
//! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
use super::*;
use rand::RngCore;
use tor_basic_utils::test_rng::testing_rng;
use tor_bytes::SecretBuf;
use tor_cell::relaycell::RelayCellFormatV0;
fn add_layers(
cc_out: &mut OutboundClientCrypt,
cc_in: &mut InboundClientCrypt,
// TODO #1067: test other formats
pair: Tor1RelayCrypto<RelayCellFormatV0>,
) {
let (outbound, inbound, _) = pair.split();
cc_out.add_layer(Box::new(outbound));
cc_in.add_layer(Box::new(inbound));
}
#[test]
fn roundtrip() {
// Take canned keys and make sure we can do crypto correctly.
use crate::crypto::handshake::ShakeKeyGenerator as KGen;
fn s(seed: &[u8]) -> SecretBuf {
seed.to_vec().into()
}
let seed1 = s(b"hidden we are free");
let seed2 = s(b"free to speak, to free ourselves");
let seed3 = s(b"free to hide no more");
let mut cc_out = OutboundClientCrypt::new();
let mut cc_in = InboundClientCrypt::new();
let pair = Tor1RelayCrypto::construct(KGen::new(seed1.clone())).unwrap();
add_layers(&mut cc_out, &mut cc_in, pair);
let pair = Tor1RelayCrypto::construct(KGen::new(seed2.clone())).unwrap();
add_layers(&mut cc_out, &mut cc_in, pair);
let pair = Tor1RelayCrypto::construct(KGen::new(seed3.clone())).unwrap();
add_layers(&mut cc_out, &mut cc_in, pair);
assert_eq!(cc_in.n_layers(), 3);
assert_eq!(cc_out.n_layers(), 3);
let mut r1 = Tor1RelayCrypto::<RelayCellFormatV0>::construct(KGen::new(seed1)).unwrap();
let mut r2 = Tor1RelayCrypto::<RelayCellFormatV0>::construct(KGen::new(seed2)).unwrap();
let mut r3 = Tor1RelayCrypto::<RelayCellFormatV0>::construct(KGen::new(seed3)).unwrap();
let mut rng = testing_rng();
for _ in 1..300 {
// outbound cell
let mut cell = Box::new([0_u8; 509]);
let mut cell_orig = [0_u8; 509];
rng.fill_bytes(&mut cell_orig);
cell.copy_from_slice(&cell_orig);
let mut cell = cell.into();
let _tag = cc_out.encrypt(&mut cell, 2.into()).unwrap();
assert_ne!(&cell.as_ref()[9..], &cell_orig.as_ref()[9..]);
assert!(!r1.decrypt_outbound(&mut cell));
assert!(!r2.decrypt_outbound(&mut cell));
assert!(r3.decrypt_outbound(&mut cell));
assert_eq!(&cell.as_ref()[9..], &cell_orig.as_ref()[9..]);
// inbound cell
let mut cell = Box::new([0_u8; 509]);
let mut cell_orig = [0_u8; 509];
rng.fill_bytes(&mut cell_orig);
cell.copy_from_slice(&cell_orig);
let mut cell = cell.into();
r3.originate(&mut cell);
r3.encrypt_inbound(&mut cell);
r2.encrypt_inbound(&mut cell);
r1.encrypt_inbound(&mut cell);
let (layer, _tag) = cc_in.decrypt(&mut cell).unwrap();
assert_eq!(layer, 2.into());
assert_eq!(&cell.as_ref()[9..], &cell_orig.as_ref()[9..]);
// TODO: Test tag somehow.
}
// Try a failure: sending a cell to a nonexistent hop.
{
let mut cell = Box::new([0_u8; 509]).into();
let err = cc_out.encrypt(&mut cell, 10.into());
assert!(matches!(err, Err(Error::NoSuchHop)));
}
// Try a failure: A junk cell with no correct auth from any layer.
{
let mut cell = Box::new([0_u8; 509]).into();
let err = cc_in.decrypt(&mut cell);
assert!(matches!(err, Err(Error::BadCellAuth)));
}
}
// From tor's test_relaycrypt.c
#[test]
fn testvec() {
use digest::XofReader;
use digest::{ExtendableOutput, Update};
// (The ....s at the end here are the KH ca)
const K1: &[u8; 92] =
b" 'My public key is in this signed x509 object', said Tom assertively. (N-PREG-VIRYL)";
const K2: &[u8; 92] =
b"'Let's chart the pedal phlanges in the tomb', said Tom cryptographically. (PELCG-GBR-TENCU)";
const K3: &[u8; 92] =
b" 'Segmentation fault bugs don't _just happen_', said Tom seethingly. (P-GUVAT-YL)";
const SEED: &[u8;108] = b"'You mean to tell me that there's a version of Sha-3 with no limit on the output length?', said Tom shakily.";
// These test vectors were generated from Tor.
let data: &[(usize, &str)] = &include!("../../testdata/cell_crypt.rs");
let mut cc_out = OutboundClientCrypt::new();
let mut cc_in = InboundClientCrypt::new();
let pair = Tor1RelayCrypto::<RelayCellFormatV0>::initialize(&K1[..]).unwrap();
add_layers(&mut cc_out, &mut cc_in, pair);
let pair = Tor1RelayCrypto::<RelayCellFormatV0>::initialize(&K2[..]).unwrap();
add_layers(&mut cc_out, &mut cc_in, pair);
let pair = Tor1RelayCrypto::<RelayCellFormatV0>::initialize(&K3[..]).unwrap();
add_layers(&mut cc_out, &mut cc_in, pair);
let mut xof = tor_llcrypto::d::Shake256::default();
xof.update(&SEED[..]);
let mut stream = xof.finalize_xof();
let mut j = 0;
for cellno in 0..51 {
let mut body = Box::new([0_u8; 509]);
body[0] = 2; // command: data.
body[4] = 1; // streamid: 1.
body[9] = 1; // length: 498
body[10] = 242;
stream.read(&mut body[11..]);
let mut cell = body.into();
let _ = cc_out.encrypt(&mut cell, 2.into());
if cellno == data[j].0 {
let expected = hex::decode(data[j].1).unwrap();
assert_eq!(cell.as_ref(), &expected[..]);
j += 1;
}
}
}
#[test]
fn hop_num_display() {
for i in 0..10 {
let hop_num = HopNum::from(i);
let expect = format!("#{}", i + 1);
assert_eq!(expect, hop_num.display().to_string());
}
}
}