linera_base/crypto/
signer.rs

1// Copyright (c) Zefchain Labs, Inc.
2// SPDX-License-Identifier: Apache-2.0
3
4/*!
5An interface for cryptographic signers that can be used by the Linera client to sign blocks.
6*/
7
8use std::error::Error as StdError;
9
10pub use in_mem::InMemorySigner;
11
12use super::CryptoHash;
13use crate::{crypto::AccountSignature, identifiers::AccountOwner};
14
15cfg_if::cfg_if! {
16    if #[cfg(web)] {
17        #[doc(hidden)]
18        pub trait TaskSendable {}
19        impl<T> TaskSendable for T {}
20    } else {
21        #[doc(hidden)]
22        pub trait TaskSendable: Send + Sync {}
23        impl<T: Send + Sync> TaskSendable for T {}
24    }
25}
26
27/// Errors that can be returned from signers.
28pub trait Error: StdError + TaskSendable {}
29impl<T: StdError + TaskSendable> Error for T {}
30
31impl StdError for Box<dyn Error + '_> {
32    fn source(&self) -> Option<&(dyn StdError + 'static)> {
33        (**self).source()
34    }
35}
36
37/// A trait for signing keys.
38#[cfg_attr(not(web), trait_variant::make(Send))]
39pub trait Signer {
40    /// The type of errors arising from operations on this `Signer`.
41    type Error: Error;
42
43    /// Creates a signature for the given `value` using the provided `owner`.
44    // DEV: We sign `CryptoHash` type, rather than `&[u8]` to make sure we don't sign
45    // things accidentally. See [`CryptoHash::new`] for how the type's name is included
46    // in the resulting hash, providing the canonicity of the hashing process.
47    async fn sign(
48        &self,
49        owner: &AccountOwner,
50        value: &CryptoHash,
51    ) -> Result<AccountSignature, Self::Error>;
52
53    /// Returns whether the given `owner` is a known signer.
54    async fn contains_key(&self, owner: &AccountOwner) -> Result<bool, Self::Error>;
55}
56
57/// In-memory implementation of the [`Signer`] trait.
58mod in_mem {
59    use std::{
60        collections::BTreeMap,
61        sync::{Arc, RwLock},
62    };
63
64    use serde::{Deserialize, Serialize};
65
66    #[cfg(with_getrandom)]
67    use crate::crypto::{AccountPublicKey, CryptoRng};
68    use crate::{
69        crypto::{AccountSecretKey, AccountSignature, CryptoHash, Signer},
70        identifiers::AccountOwner,
71    };
72
73    #[derive(Debug, thiserror::Error)]
74    pub enum Error {
75        #[error("no key found for the given owner")]
76        NoSuchOwner,
77    }
78
79    /// In-memory signer.
80    #[derive(Clone)]
81    pub struct InMemorySigner(Arc<RwLock<InMemSignerInner>>);
82
83    #[cfg(not(with_getrandom))]
84    impl Default for InMemorySigner {
85        fn default() -> Self {
86            Self::new()
87        }
88    }
89
90    impl InMemorySigner {
91        /// Creates a new [`InMemorySigner`] seeded with `prng_seed`.
92        /// If `prng_seed` is `None`, an `OsRng` will be used.
93        #[cfg(with_getrandom)]
94        pub fn new(prng_seed: Option<u64>) -> Self {
95            InMemorySigner(Arc::new(RwLock::new(InMemSignerInner::new(prng_seed))))
96        }
97
98        /// Creates a new [`InMemorySigner`].
99        #[cfg(not(with_getrandom))]
100        pub fn new() -> Self {
101            InMemorySigner(Arc::new(RwLock::new(InMemSignerInner::new())))
102        }
103
104        /// Generates a new key pair from Signer's RNG. Use with care.
105        #[cfg(with_getrandom)]
106        pub fn generate_new(&mut self) -> AccountPublicKey {
107            let mut inner = self.0.write().unwrap();
108            let secret = AccountSecretKey::generate_from(&mut inner.rng_state.prng);
109            if inner.rng_state.testing_seed.is_some() {
110                // Generate a new testing seed for the case when we need to store the PRNG state.
111                // It provides a "forward-secrecy" property for the testing seed.
112                // We do not do that for the case when `testing_seed` is `None`, because
113                // we default to the usage of OsRng in that case.
114                inner.rng_state.testing_seed = Some(inner.rng_state.prng.next_u64());
115            }
116            let public = secret.public();
117            let owner = AccountOwner::from(public);
118            inner.keys.insert(owner, secret);
119            public
120        }
121
122        /// Returns the public key corresponding to the given `owner`.
123        pub fn keys(&self) -> Vec<(AccountOwner, Vec<u8>)> {
124            let inner = self.0.read().unwrap();
125            inner.keys()
126        }
127    }
128
129    /// In-memory signer.
130    struct InMemSignerInner {
131        keys: BTreeMap<AccountOwner, AccountSecretKey>,
132        #[cfg(with_getrandom)]
133        rng_state: RngState,
134    }
135
136    #[cfg(with_getrandom)]
137    struct RngState {
138        prng: Box<dyn CryptoRng>,
139        #[cfg(with_getrandom)]
140        testing_seed: Option<u64>,
141    }
142
143    #[cfg(with_getrandom)]
144    impl RngState {
145        fn new(prng_seed: Option<u64>) -> Self {
146            let prng: Box<dyn CryptoRng> = prng_seed.into();
147            RngState {
148                prng,
149                #[cfg(with_getrandom)]
150                testing_seed: prng_seed,
151            }
152        }
153    }
154
155    impl InMemSignerInner {
156        /// Creates a new `InMemSignerInner` seeded with `prng_seed`.
157        /// If `prng_seed` is `None`, an `OsRng` will be used.
158        #[cfg(with_getrandom)]
159        pub fn new(prng_seed: Option<u64>) -> Self {
160            InMemSignerInner {
161                keys: BTreeMap::new(),
162                rng_state: RngState::new(prng_seed),
163            }
164        }
165
166        /// Creates a new `InMemSignerInner`.
167        #[cfg(not(with_getrandom))]
168        pub fn new() -> Self {
169            InMemSignerInner {
170                keys: BTreeMap::new(),
171            }
172        }
173
174        pub fn keys(&self) -> Vec<(AccountOwner, Vec<u8>)> {
175            self.keys
176                .iter()
177                .map(|(owner, secret)| {
178                    (
179                        *owner,
180                        serde_json::to_vec(secret).expect("serialization should not fail"),
181                    )
182                })
183                .collect()
184        }
185    }
186
187    impl Signer for InMemorySigner {
188        type Error = Error;
189
190        /// Creates a signature for the given `value` using the provided `owner`.
191        async fn sign(
192            &self,
193            owner: &AccountOwner,
194            value: &CryptoHash,
195        ) -> Result<AccountSignature, Error> {
196            let inner = self.0.read().unwrap();
197            if let Some(secret) = inner.keys.get(owner) {
198                let signature = secret.sign_prehash(*value);
199                Ok(signature)
200            } else {
201                Err(Error::NoSuchOwner)
202            }
203        }
204
205        /// Returns whether the given `owner` is a known signer.
206        async fn contains_key(&self, owner: &AccountOwner) -> Result<bool, Error> {
207            Ok(self.0.read().unwrap().keys.contains_key(owner))
208        }
209    }
210
211    impl FromIterator<(AccountOwner, AccountSecretKey)> for InMemorySigner {
212        fn from_iter<T>(input: T) -> Self
213        where
214            T: IntoIterator<Item = (AccountOwner, AccountSecretKey)>,
215        {
216            InMemorySigner(Arc::new(RwLock::new(InMemSignerInner {
217                keys: BTreeMap::from_iter(input),
218                #[cfg(with_getrandom)]
219                rng_state: RngState::new(None),
220            })))
221        }
222    }
223
224    impl Default for InMemSignerInner {
225        fn default() -> Self {
226            #[cfg(with_getrandom)]
227            let signer = InMemSignerInner::new(None);
228            #[cfg(not(with_getrandom))]
229            let signer = InMemSignerInner::new();
230            signer
231        }
232    }
233
234    impl Serialize for InMemorySigner {
235        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
236        where
237            S: serde::Serializer,
238        {
239            let inner = self.0.read().unwrap();
240            InMemSignerInner::serialize(&*inner, serializer)
241        }
242    }
243
244    impl<'de> Deserialize<'de> for InMemorySigner {
245        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
246        where
247            D: serde::Deserializer<'de>,
248        {
249            let inner = InMemSignerInner::deserialize(deserializer)?;
250            Ok(InMemorySigner(Arc::new(RwLock::new(inner))))
251        }
252    }
253
254    impl Serialize for InMemSignerInner {
255        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
256        where
257            S: serde::Serializer,
258        {
259            #[derive(Serialize, Debug)]
260            struct Inner<'a> {
261                keys: &'a Vec<(AccountOwner, Vec<u8>)>,
262                #[cfg(with_getrandom)]
263                prng_seed: Option<u64>,
264            }
265
266            #[cfg(with_getrandom)]
267            let prng_seed = self.rng_state.testing_seed;
268
269            let inner = Inner {
270                keys: &self.keys(),
271                #[cfg(with_getrandom)]
272                prng_seed,
273            };
274
275            Inner::serialize(&inner, serializer)
276        }
277    }
278
279    impl<'de> Deserialize<'de> for InMemSignerInner {
280        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
281        where
282            D: serde::Deserializer<'de>,
283        {
284            #[derive(Deserialize)]
285            struct Inner {
286                keys: Vec<(AccountOwner, Vec<u8>)>,
287                #[cfg(with_getrandom)]
288                prng_seed: Option<u64>,
289            }
290
291            let inner = Inner::deserialize(deserializer)?;
292
293            let keys = inner
294                .keys
295                .into_iter()
296                .map(|(owner, secret)| {
297                    let secret =
298                        serde_json::from_slice(&secret).map_err(serde::de::Error::custom)?;
299                    Ok((owner, secret))
300                })
301                .collect::<Result<BTreeMap<_, _>, _>>()?;
302
303            let signer = InMemSignerInner {
304                keys,
305                #[cfg(with_getrandom)]
306                rng_state: RngState::new(inner.prng_seed),
307            };
308            Ok(signer)
309        }
310    }
311}
linera_base/crypto/signer.rs

linera_base/crypto/
signer.rs
