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        /// Removes the key for `owner`, returning whether one was present. Useful to
129        /// simulate a key becoming unavailable (e.g. an autosigner key that is rotated or
130        /// withdrawn after a block was already staged by it).
131        pub fn forget_key(&self, owner: &AccountOwner) -> bool {
132            self.0.write().unwrap().keys.remove(owner).is_some()
133        }
134    }
135
136    /// In-memory signer.
137    struct InMemSignerInner {
138        keys: BTreeMap<AccountOwner, AccountSecretKey>,
139        #[cfg(with_getrandom)]
140        rng_state: RngState,
141    }
142
143    #[cfg(with_getrandom)]
144    struct RngState {
145        prng: Box<dyn CryptoRng>,
146        #[cfg(with_getrandom)]
147        testing_seed: Option<u64>,
148    }
149
150    #[cfg(with_getrandom)]
151    impl RngState {
152        fn new(prng_seed: Option<u64>) -> Self {
153            let prng: Box<dyn CryptoRng> = prng_seed.into();
154            RngState {
155                prng,
156                #[cfg(with_getrandom)]
157                testing_seed: prng_seed,
158            }
159        }
160    }
161
162    impl InMemSignerInner {
163        /// Creates a new `InMemSignerInner` seeded with `prng_seed`.
164        /// If `prng_seed` is `None`, an `OsRng` will be used.
165        #[cfg(with_getrandom)]
166        pub fn new(prng_seed: Option<u64>) -> Self {
167            InMemSignerInner {
168                keys: BTreeMap::new(),
169                rng_state: RngState::new(prng_seed),
170            }
171        }
172
173        /// Creates a new `InMemSignerInner`.
174        #[cfg(not(with_getrandom))]
175        pub fn new() -> Self {
176            InMemSignerInner {
177                keys: BTreeMap::new(),
178            }
179        }
180
181        pub fn keys(&self) -> Vec<(AccountOwner, Vec<u8>)> {
182            self.keys
183                .iter()
184                .map(|(owner, secret)| {
185                    (
186                        *owner,
187                        serde_json::to_vec(secret).expect("serialization should not fail"),
188                    )
189                })
190                .collect()
191        }
192    }
193
194    impl Signer for InMemorySigner {
195        type Error = Error;
196
197        /// Creates a signature for the given `value` using the provided `owner`.
198        async fn sign(
199            &self,
200            owner: &AccountOwner,
201            value: &CryptoHash,
202        ) -> Result<AccountSignature, Error> {
203            let inner = self.0.read().unwrap();
204            if let Some(secret) = inner.keys.get(owner) {
205                let signature = secret.sign_prehash(*value);
206                Ok(signature)
207            } else {
208                Err(Error::NoSuchOwner)
209            }
210        }
211
212        /// Returns whether the given `owner` is a known signer.
213        async fn contains_key(&self, owner: &AccountOwner) -> Result<bool, Error> {
214            Ok(self.0.read().unwrap().keys.contains_key(owner))
215        }
216    }
217
218    impl FromIterator<(AccountOwner, AccountSecretKey)> for InMemorySigner {
219        fn from_iter<T>(input: T) -> Self
220        where
221            T: IntoIterator<Item = (AccountOwner, AccountSecretKey)>,
222        {
223            InMemorySigner(Arc::new(RwLock::new(InMemSignerInner {
224                keys: BTreeMap::from_iter(input),
225                #[cfg(with_getrandom)]
226                rng_state: RngState::new(None),
227            })))
228        }
229    }
230
231    impl Default for InMemSignerInner {
232        fn default() -> Self {
233            #[cfg(with_getrandom)]
234            let signer = InMemSignerInner::new(None);
235            #[cfg(not(with_getrandom))]
236            let signer = InMemSignerInner::new();
237            signer
238        }
239    }
240
241    impl Serialize for InMemorySigner {
242        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
243        where
244            S: serde::Serializer,
245        {
246            let inner = self.0.read().unwrap();
247            InMemSignerInner::serialize(&*inner, serializer)
248        }
249    }
250
251    impl<'de> Deserialize<'de> for InMemorySigner {
252        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
253        where
254            D: serde::Deserializer<'de>,
255        {
256            let inner = InMemSignerInner::deserialize(deserializer)?;
257            Ok(InMemorySigner(Arc::new(RwLock::new(inner))))
258        }
259    }
260
261    impl Serialize for InMemSignerInner {
262        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
263        where
264            S: serde::Serializer,
265        {
266            #[derive(Serialize, Debug)]
267            struct Inner<'a> {
268                keys: &'a Vec<(AccountOwner, Vec<u8>)>,
269                #[cfg(with_getrandom)]
270                prng_seed: Option<u64>,
271            }
272
273            #[cfg(with_getrandom)]
274            let prng_seed = self.rng_state.testing_seed;
275
276            let inner = Inner {
277                keys: &self.keys(),
278                #[cfg(with_getrandom)]
279                prng_seed,
280            };
281
282            Inner::serialize(&inner, serializer)
283        }
284    }
285
286    impl<'de> Deserialize<'de> for InMemSignerInner {
287        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
288        where
289            D: serde::Deserializer<'de>,
290        {
291            #[derive(Deserialize)]
292            struct Inner {
293                keys: Vec<(AccountOwner, Vec<u8>)>,
294                #[cfg(with_getrandom)]
295                prng_seed: Option<u64>,
296            }
297
298            let inner = Inner::deserialize(deserializer)?;
299
300            let keys = inner
301                .keys
302                .into_iter()
303                .map(|(owner, secret)| {
304                    let secret =
305                        serde_json::from_slice(&secret).map_err(serde::de::Error::custom)?;
306                    Ok((owner, secret))
307                })
308                .collect::<Result<BTreeMap<_, _>, _>>()?;
309
310            let signer = InMemSignerInner {
311                keys,
312                #[cfg(with_getrandom)]
313                rng_state: RngState::new(inner.prng_seed),
314            };
315            Ok(signer)
316        }
317    }
318}
linera_base/crypto/signer.rs

linera_base/crypto/
signer.rs
