rustls/
suites.rs

1use core::fmt;
2
3use crate::common_state::Protocol;
4use crate::crypto::cipher::{AeadKey, Iv};
5use crate::crypto::{self, KeyExchangeAlgorithm};
6use crate::enums::{CipherSuite, SignatureAlgorithm, SignatureScheme};
7use crate::msgs::handshake::ALL_KEY_EXCHANGE_ALGORITHMS;
8#[cfg(feature = "tls12")]
9use crate::tls12::Tls12CipherSuite;
10use crate::tls13::Tls13CipherSuite;
11#[cfg(feature = "tls12")]
12use crate::versions::TLS12;
13use crate::versions::{SupportedProtocolVersion, TLS13};
14
15/// Common state for cipher suites (both for TLS 1.2 and TLS 1.3)
16pub struct CipherSuiteCommon {
17    /// The TLS enumeration naming this cipher suite.
18    pub suite: CipherSuite,
19
20    /// Which hash function the suite uses.
21    pub hash_provider: &'static dyn crypto::hash::Hash,
22
23    /// Number of TCP-TLS messages that can be safely encrypted with a single key of this type
24    ///
25    /// Once a `MessageEncrypter` produced for this suite has encrypted more than
26    /// `confidentiality_limit` messages, an attacker gains an advantage in distinguishing it
27    /// from an ideal pseudorandom permutation (PRP).
28    ///
29    /// This is to be set on the assumption that messages are maximally sized --
30    /// each is 2<sup>14</sup> bytes. It **does not** consider confidentiality limits for
31    /// QUIC connections - see the [`quic::KeyBuilder.confidentiality_limit`] field for
32    /// this context.
33    ///
34    /// For AES-GCM implementations, this should be set to 2<sup>24</sup> to limit attack
35    /// probability to one in 2<sup>60</sup>.  See [AEBounds] (Table 1) and [draft-irtf-aead-limits-08]:
36    ///
37    /// ```python
38    /// >>> p = 2 ** -60
39    /// >>> L = (2 ** 14 // 16) + 1
40    /// >>> qlim = (math.sqrt(p) * (2 ** (129 // 2)) - 1) / (L + 1)
41    /// >>> print(int(qlim).bit_length())
42    /// 24
43    /// ```
44    /// [AEBounds]: https://eprint.iacr.org/2024/051.pdf
45    /// [draft-irtf-aead-limits-08]: https://www.ietf.org/archive/id/draft-irtf-cfrg-aead-limits-08.html#section-5.1.1
46    ///
47    /// For chacha20-poly1305 implementations, this should be set to `u64::MAX`:
48    /// see <https://www.ietf.org/archive/id/draft-irtf-cfrg-aead-limits-08.html#section-5.2.1>
49    pub confidentiality_limit: u64,
50}
51
52impl CipherSuiteCommon {
53    /// Return `true` if this is backed by a FIPS-approved implementation.
54    ///
55    /// This means all the constituent parts that do cryptography return `true` for `fips()`.
56    pub fn fips(&self) -> bool {
57        self.hash_provider.fips()
58    }
59}
60
61/// A cipher suite supported by rustls.
62///
63/// This type carries both configuration and implementation. Compare with
64/// [`CipherSuite`], which carries solely a cipher suite identifier.
65#[derive(Clone, Copy, PartialEq)]
66pub enum SupportedCipherSuite {
67    /// A TLS 1.2 cipher suite
68    #[cfg(feature = "tls12")]
69    Tls12(&'static Tls12CipherSuite),
70    /// A TLS 1.3 cipher suite
71    Tls13(&'static Tls13CipherSuite),
72}
73
74impl SupportedCipherSuite {
75    /// The cipher suite's identifier
76    pub fn suite(&self) -> CipherSuite {
77        self.common().suite
78    }
79
80    /// The hash function the ciphersuite uses.
81    pub(crate) fn hash_provider(&self) -> &'static dyn crypto::hash::Hash {
82        self.common().hash_provider
83    }
84
85    pub(crate) fn common(&self) -> &CipherSuiteCommon {
86        match self {
87            #[cfg(feature = "tls12")]
88            Self::Tls12(inner) => &inner.common,
89            Self::Tls13(inner) => &inner.common,
90        }
91    }
92
93    /// Return the inner `Tls13CipherSuite` for this suite, if it is a TLS1.3 suite.
94    pub fn tls13(&self) -> Option<&'static Tls13CipherSuite> {
95        match self {
96            #[cfg(feature = "tls12")]
97            Self::Tls12(_) => None,
98            Self::Tls13(inner) => Some(inner),
99        }
100    }
101
102    /// Return supported protocol version for the cipher suite.
103    pub fn version(&self) -> &'static SupportedProtocolVersion {
104        match self {
105            #[cfg(feature = "tls12")]
106            Self::Tls12(_) => &TLS12,
107            Self::Tls13(_) => &TLS13,
108        }
109    }
110
111    /// Return true if this suite is usable for a key only offering `sig_alg`
112    /// signatures.  This resolves to true for all TLS1.3 suites.
113    pub fn usable_for_signature_algorithm(&self, _sig_alg: SignatureAlgorithm) -> bool {
114        match self {
115            Self::Tls13(_) => true, // no constraint expressed by ciphersuite (e.g., TLS1.3)
116            #[cfg(feature = "tls12")]
117            Self::Tls12(inner) => inner
118                .sign
119                .iter()
120                .any(|scheme| scheme.algorithm() == _sig_alg),
121        }
122    }
123
124    /// Return true if this suite is usable for the given [`Protocol`].
125    ///
126    /// All cipher suites are usable for TCP-TLS.  Only TLS1.3 suites
127    /// with `Tls13CipherSuite::quic` provided are usable for QUIC.
128    pub(crate) fn usable_for_protocol(&self, proto: Protocol) -> bool {
129        match proto {
130            Protocol::Tcp => true,
131            Protocol::Quic => self
132                .tls13()
133                .and_then(|cs| cs.quic)
134                .is_some(),
135        }
136    }
137
138    /// Return `true` if this is backed by a FIPS-approved implementation.
139    pub fn fips(&self) -> bool {
140        match self {
141            #[cfg(feature = "tls12")]
142            Self::Tls12(cs) => cs.fips(),
143            Self::Tls13(cs) => cs.fips(),
144        }
145    }
146
147    /// Return the list of `KeyExchangeAlgorithm`s supported by this cipher suite.
148    ///
149    /// TLS 1.3 cipher suites support both ECDHE and DHE key exchange, but TLS 1.2 suites
150    /// support one or the other.
151    pub(crate) fn key_exchange_algorithms(&self) -> &[KeyExchangeAlgorithm] {
152        match self {
153            #[cfg(feature = "tls12")]
154            Self::Tls12(tls12) => core::slice::from_ref(&tls12.kx),
155            Self::Tls13(_) => ALL_KEY_EXCHANGE_ALGORITHMS,
156        }
157    }
158
159    /// Say if the given `KeyExchangeAlgorithm` is supported by this cipher suite.
160    ///
161    /// TLS 1.3 cipher suites support all key exchange types, but TLS 1.2 suites
162    /// support only one.
163    pub(crate) fn usable_for_kx_algorithm(&self, _kxa: KeyExchangeAlgorithm) -> bool {
164        match self {
165            #[cfg(feature = "tls12")]
166            Self::Tls12(tls12) => tls12.kx == _kxa,
167            Self::Tls13(_) => true,
168        }
169    }
170}
171
172impl fmt::Debug for SupportedCipherSuite {
173    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
174        self.suite().fmt(f)
175    }
176}
177
178/// Return true if `sigscheme` is usable by any of the given suites.
179pub(crate) fn compatible_sigscheme_for_suites(
180    sigscheme: SignatureScheme,
181    common_suites: &[SupportedCipherSuite],
182) -> bool {
183    let sigalg = sigscheme.algorithm();
184    common_suites
185        .iter()
186        .any(|&suite| suite.usable_for_signature_algorithm(sigalg))
187}
188
189/// Secrets for transmitting/receiving data over a TLS session.
190///
191/// After performing a handshake with rustls, these secrets can be extracted
192/// to configure kTLS for a socket, and have the kernel take over encryption
193/// and/or decryption.
194pub struct ExtractedSecrets {
195    /// sequence number and secrets for the "tx" (transmit) direction
196    pub tx: (u64, ConnectionTrafficSecrets),
197
198    /// sequence number and secrets for the "rx" (receive) direction
199    pub rx: (u64, ConnectionTrafficSecrets),
200}
201
202/// [ExtractedSecrets] minus the sequence numbers
203pub(crate) struct PartiallyExtractedSecrets {
204    /// secrets for the "tx" (transmit) direction
205    pub(crate) tx: ConnectionTrafficSecrets,
206
207    /// secrets for the "rx" (receive) direction
208    pub(crate) rx: ConnectionTrafficSecrets,
209}
210
211/// Secrets used to encrypt/decrypt data in a TLS session.
212///
213/// These can be used to configure kTLS for a socket in one direction.
214/// The only other piece of information needed is the sequence number,
215/// which is in [ExtractedSecrets].
216#[non_exhaustive]
217pub enum ConnectionTrafficSecrets {
218    /// Secrets for the AES_128_GCM AEAD algorithm
219    Aes128Gcm {
220        /// AEAD Key
221        key: AeadKey,
222        /// Initialization vector
223        iv: Iv,
224    },
225
226    /// Secrets for the AES_256_GCM AEAD algorithm
227    Aes256Gcm {
228        /// AEAD Key
229        key: AeadKey,
230        /// Initialization vector
231        iv: Iv,
232    },
233
234    /// Secrets for the CHACHA20_POLY1305 AEAD algorithm
235    Chacha20Poly1305 {
236        /// AEAD Key
237        key: AeadKey,
238        /// Initialization vector
239        iv: Iv,
240    },
241}
242
243#[cfg(test)]
244#[macro_rules_attribute::apply(test_for_each_provider)]
245mod tests {
246    use std::println;
247
248    use super::provider::tls13::*;
249
250    #[test]
251    fn test_scs_is_debug() {
252        println!("{:?}", super::provider::ALL_CIPHER_SUITES);
253    }
254
255    #[test]
256    fn test_can_resume_to() {
257        assert!(TLS13_AES_128_GCM_SHA256
258            .tls13()
259            .unwrap()
260            .can_resume_from(TLS13_CHACHA20_POLY1305_SHA256_INTERNAL)
261            .is_some());
262        assert!(TLS13_AES_256_GCM_SHA384
263            .tls13()
264            .unwrap()
265            .can_resume_from(TLS13_CHACHA20_POLY1305_SHA256_INTERNAL)
266            .is_none());
267    }
268}
rustls/suites.rs

rustls/
suites.rs
