1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
// Copyright 2019 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

//! Components of a Noise protocol.

pub mod x25519;
pub mod x25519_spec;

use crate::NoiseError;
use libp2p_core::identity;
use rand::SeedableRng;
use zeroize::Zeroize;

/// The parameters of a Noise protocol, consisting of a choice
/// for a handshake pattern as well as DH, cipher and hash functions.
#[derive(Clone)]
pub struct ProtocolParams(snow::params::NoiseParams);

impl ProtocolParams {
    /// Turn the protocol parameters into a session builder.
    pub(crate) fn into_builder(self) -> snow::Builder<'static> {
        snow::Builder::with_resolver(self.0, Box::new(Resolver))
    }
}

/// Type tag for the IK handshake pattern.
#[derive(Debug, Clone)]
pub enum IK {}

/// Type tag for the IX handshake pattern.
#[derive(Debug, Clone)]
pub enum IX {}

/// Type tag for the XX handshake pattern.
#[derive(Debug, Clone)]
pub enum XX {}

/// A Noise protocol over DH keys of type `C`. The choice of `C` determines the
/// protocol parameters for each handshake pattern.
pub trait Protocol<C> {
    /// The protocol parameters for the IK handshake pattern.
    fn params_ik() -> ProtocolParams;
    /// The protocol parameters for the IX handshake pattern.
    fn params_ix() -> ProtocolParams;
    /// The protocol parameters for the XX handshake pattern.
    fn params_xx() -> ProtocolParams;

    /// Construct a DH public key from a byte slice.
    fn public_from_bytes(s: &[u8]) -> Result<PublicKey<C>, NoiseError>;

    /// Determines whether the authenticity of the given DH static public key
    /// and public identity key is linked, i.e. that proof of ownership of a
    /// secret key for the static DH public key implies that the key is
    /// authentic w.r.t. the given public identity key.
    ///
    /// The trivial case is when the keys are byte for byte identical.
    #[allow(unused_variables)]
    #[deprecated]
    fn linked(id_pk: &identity::PublicKey, dh_pk: &PublicKey<C>) -> bool {
        false
    }

    /// Verifies that a given static DH public key is authentic w.r.t. a
    /// given public identity key in the context of an optional signature.
    ///
    /// The given static DH public key is assumed to already be authentic
    /// in the sense that possession of a corresponding secret key has been
    /// established, as is the case at the end of a Noise handshake involving
    /// static DH keys.
    ///
    /// If the public keys are [`linked`](Protocol::linked), verification succeeds
    /// without a signature, otherwise a signature over the static DH public key
    /// must be given and is verified with the public identity key, establishing
    /// the authenticity of the static DH public key w.r.t. the public identity key.
    #[allow(deprecated)]
    fn verify(id_pk: &identity::PublicKey, dh_pk: &PublicKey<C>, sig: &Option<Vec<u8>>) -> bool
    where
        C: AsRef<[u8]>
    {
        Self::linked(id_pk, dh_pk)
            ||
        sig.as_ref().map_or(false, |s| id_pk.verify(dh_pk.as_ref(), s))
    }

    fn sign(id_keys: &identity::Keypair, dh_pk: &PublicKey<C>) -> Result<Vec<u8>, NoiseError>
    where
        C: AsRef<[u8]>
    {
        Ok(id_keys.sign(dh_pk.as_ref())?)
    }
}

/// DH keypair.
#[derive(Clone)]
pub struct Keypair<T: Zeroize> {
    secret: SecretKey<T>,
    public: PublicKey<T>,
}

/// A DH keypair that is authentic w.r.t. a [`identity::PublicKey`].
#[derive(Clone)]
pub struct AuthenticKeypair<T: Zeroize> {
    keypair: Keypair<T>,
    identity: KeypairIdentity
}

impl<T: Zeroize> AuthenticKeypair<T> {
    /// Extract the public [`KeypairIdentity`] from this `AuthenticKeypair`,
    /// dropping the DH `Keypair`.
    pub fn into_identity(self) -> KeypairIdentity {
        self.identity
    }
}

impl<T: Zeroize> std::ops::Deref for AuthenticKeypair<T> {
    type Target = Keypair<T>;

    fn deref(&self) -> &Self::Target {
        &self.keypair
    }
}

/// The associated public identity of a DH keypair.
#[derive(Clone)]
pub struct KeypairIdentity {
    /// The public identity key.
    pub public: identity::PublicKey,
    /// The signature over the public DH key.
    pub signature: Option<Vec<u8>>
}

impl<T: Zeroize> Keypair<T> {
    /// The public key of the DH keypair.
    pub fn public(&self) -> &PublicKey<T> {
        &self.public
    }

    /// The secret key of the DH keypair.
    pub fn secret(&self) -> &SecretKey<T> {
        &self.secret
    }

    /// Turn this DH keypair into a [`AuthenticKeypair`], i.e. a DH keypair that
    /// is authentic w.r.t. the given identity keypair, by signing the DH public key.
    pub fn into_authentic(self, id_keys: &identity::Keypair) -> Result<AuthenticKeypair<T>, NoiseError>
    where
        T: AsRef<[u8]>,
        T: Protocol<T>
    {
        let sig = T::sign(id_keys, &self.public)?;

        let identity = KeypairIdentity {
            public: id_keys.public(),
            signature: Some(sig)
        };

        Ok(AuthenticKeypair { keypair: self, identity })
    }
}

/// DH secret key.
#[derive(Clone)]
pub struct SecretKey<T: Zeroize>(T);

impl<T: Zeroize> Drop for SecretKey<T> {
    fn drop(&mut self) {
        self.0.zeroize()
    }
}

impl<T: AsRef<[u8]> + Zeroize> AsRef<[u8]> for SecretKey<T> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

/// DH public key.
#[derive(Clone)]
pub struct PublicKey<T>(T);

impl<T: AsRef<[u8]>> PartialEq for PublicKey<T> {
    fn eq(&self, other: &PublicKey<T>) -> bool {
        self.as_ref() == other.as_ref()
    }
}

impl<T: AsRef<[u8]>> Eq for PublicKey<T> {}

impl<T: AsRef<[u8]>> AsRef<[u8]> for PublicKey<T> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

/// Custom `snow::CryptoResolver` which delegates to either the
/// `RingResolver` on native or the `DefaultResolver` on wasm
/// for hash functions and symmetric ciphers, while using x25519-dalek
/// for Curve25519 DH.
struct Resolver;

impl snow::resolvers::CryptoResolver for Resolver {
    fn resolve_rng(&self) -> Option<Box<dyn snow::types::Random>> {
        Some(Box::new(Rng(rand::rngs::StdRng::from_entropy())))
    }

    fn resolve_dh(&self, choice: &snow::params::DHChoice) -> Option<Box<dyn snow::types::Dh>> {
        if let snow::params::DHChoice::Curve25519 = choice {
            Some(Box::new(Keypair::<x25519::X25519>::default()))
        } else {
            None
        }
    }

    fn resolve_hash(&self, choice: &snow::params::HashChoice) -> Option<Box<dyn snow::types::Hash>> {
        #[cfg(target_arch = "wasm32")]
        {
            snow::resolvers::DefaultResolver.resolve_hash(choice)
        }
        #[cfg(not(target_arch = "wasm32"))]
        {
            snow::resolvers::RingResolver.resolve_hash(choice)
        }
    }

    fn resolve_cipher(&self, choice: &snow::params::CipherChoice) -> Option<Box<dyn snow::types::Cipher>> {
        #[cfg(target_arch = "wasm32")]
        {
            snow::resolvers::DefaultResolver.resolve_cipher(choice)
        }
        #[cfg(not(target_arch = "wasm32"))]
        {
            snow::resolvers::RingResolver.resolve_cipher(choice)
        }
    }
}

/// Wrapper around a CSPRNG to implement `snow::Random` trait for.
struct Rng(rand::rngs::StdRng);

impl rand::RngCore for Rng {
    fn next_u32(&mut self) -> u32 {
        self.0.next_u32()
    }

    fn next_u64(&mut self) -> u64 {
        self.0.next_u64()
    }

    fn fill_bytes(&mut self, dest: &mut [u8]) {
        self.0.fill_bytes(dest)
    }

    fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand::Error> {
        self.0.try_fill_bytes(dest)
    }
}

impl rand::CryptoRng for Rng {}

impl snow::types::Random for Rng {}