rustls/crypto/ring/
kx.rs

1#![allow(clippy::duplicate_mod)]
2
3use crate::crypto::{ActiveKeyExchange, SharedSecret, SupportedKxGroup};
4use crate::error::{Error, PeerMisbehaved};
5use crate::msgs::enums::NamedGroup;
6use crate::rand::GetRandomFailed;
7
8use super::ring_like::agreement;
9use super::ring_like::rand::SystemRandom;
10
11use alloc::boxed::Box;
12use core::fmt;
13
14/// A key-exchange group supported by *ring*.
15///
16/// All possible instances of this class are provided by the library in
17/// the [`ALL_KX_GROUPS`] array.
18struct KxGroup {
19    /// The IANA "TLS Supported Groups" name of the group
20    name: NamedGroup,
21
22    /// The corresponding ring agreement::Algorithm
23    agreement_algorithm: &'static agreement::Algorithm,
24}
25
26impl SupportedKxGroup for KxGroup {
27    fn start(&self) -> Result<Box<dyn ActiveKeyExchange>, Error> {
28        let rng = SystemRandom::new();
29        let priv_key = agreement::EphemeralPrivateKey::generate(self.agreement_algorithm, &rng)
30            .map_err(|_| GetRandomFailed)?;
31
32        let pub_key = priv_key
33            .compute_public_key()
34            .map_err(|_| GetRandomFailed)?;
35
36        Ok(Box::new(KeyExchange {
37            name: self.name,
38            agreement_algorithm: self.agreement_algorithm,
39            priv_key,
40            pub_key,
41        }))
42    }
43
44    fn name(&self) -> NamedGroup {
45        self.name
46    }
47}
48
49impl fmt::Debug for KxGroup {
50    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
51        self.name.fmt(f)
52    }
53}
54
55/// Ephemeral ECDH on curve25519 (see RFC7748)
56pub static X25519: &dyn SupportedKxGroup = &KxGroup {
57    name: NamedGroup::X25519,
58    agreement_algorithm: &agreement::X25519,
59};
60
61/// Ephemeral ECDH on secp256r1 (aka NIST-P256)
62pub static SECP256R1: &dyn SupportedKxGroup = &KxGroup {
63    name: NamedGroup::secp256r1,
64    agreement_algorithm: &agreement::ECDH_P256,
65};
66
67/// Ephemeral ECDH on secp384r1 (aka NIST-P384)
68pub static SECP384R1: &dyn SupportedKxGroup = &KxGroup {
69    name: NamedGroup::secp384r1,
70    agreement_algorithm: &agreement::ECDH_P384,
71};
72
73/// A list of all the key exchange groups supported by rustls.
74pub static ALL_KX_GROUPS: &[&dyn SupportedKxGroup] = &[X25519, SECP256R1, SECP384R1];
75
76/// An in-progress key exchange.  This has the algorithm,
77/// our private key, and our public key.
78struct KeyExchange {
79    name: NamedGroup,
80    agreement_algorithm: &'static agreement::Algorithm,
81    priv_key: agreement::EphemeralPrivateKey,
82    pub_key: agreement::PublicKey,
83}
84
85impl ActiveKeyExchange for KeyExchange {
86    /// Completes the key exchange, given the peer's public key.
87    fn complete(self: Box<Self>, peer: &[u8]) -> Result<SharedSecret, Error> {
88        let peer_key = agreement::UnparsedPublicKey::new(self.agreement_algorithm, peer);
89        super::ring_shim::agree_ephemeral(self.priv_key, &peer_key)
90            .map_err(|_| PeerMisbehaved::InvalidKeyShare.into())
91    }
92
93    /// Return the group being used.
94    fn group(&self) -> NamedGroup {
95        self.name
96    }
97
98    /// Return the public key being used.
99    fn pub_key(&self) -> &[u8] {
100        self.pub_key.as_ref()
101    }
102}
103
104#[cfg(test)]
105mod tests {
106    use std::format;
107
108    #[test]
109    fn kxgroup_fmt_yields_name() {
110        assert_eq!("X25519", format!("{:?}", super::X25519));
111    }
112}
113
114#[cfg(bench)]
115mod benchmarks {
116    #[bench]
117    fn bench_x25519(b: &mut test::Bencher) {
118        bench_any(b, super::X25519);
119    }
120
121    #[bench]
122    fn bench_ecdh_p256(b: &mut test::Bencher) {
123        bench_any(b, super::SECP256R1);
124    }
125
126    #[bench]
127    fn bench_ecdh_p384(b: &mut test::Bencher) {
128        bench_any(b, super::SECP384R1);
129    }
130
131    fn bench_any(b: &mut test::Bencher, kxg: &dyn super::SupportedKxGroup) {
132        b.iter(|| {
133            let akx = kxg.start().unwrap();
134            let pub_key = akx.pub_key().to_vec();
135            test::black_box(akx.complete(&pub_key).unwrap());
136        });
137    }
138}
rustls/crypto/ring/kx.rs

rustls/crypto/ring/
kx.rs
