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    #[derive(Debug, Deserialize, Serialize)]
130    struct Inner {
131        keys: Vec<(AccountOwner, String)>,
132        #[cfg(with_getrandom)]
133        prng_seed: Option<u64>,
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                    let bytes = serde_json::to_vec(secret).expect("serialization should not fail");
186                    (*owner, bytes)
187                })
188                .collect()
189        }
190    }
191
192    impl Signer for InMemorySigner {
193        type Error = Error;
194
195        /// Creates a signature for the given `value` using the provided `owner`.
196        async fn sign(
197            &self,
198            owner: &AccountOwner,
199            value: &CryptoHash,
200        ) -> Result<AccountSignature, Error> {
201            let inner = self.0.read().unwrap();
202            if let Some(secret) = inner.keys.get(owner) {
203                let signature = secret.sign_prehash(*value);
204                Ok(signature)
205            } else {
206                Err(Error::NoSuchOwner)
207            }
208        }
209
210        /// Returns whether the given `owner` is a known signer.
211        async fn contains_key(&self, owner: &AccountOwner) -> Result<bool, Error> {
212            Ok(self.0.read().unwrap().keys.contains_key(owner))
213        }
214    }
215
216    impl FromIterator<(AccountOwner, AccountSecretKey)> for InMemorySigner {
217        fn from_iter<T>(input: T) -> Self
218        where
219            T: IntoIterator<Item = (AccountOwner, AccountSecretKey)>,
220        {
221            InMemorySigner(Arc::new(RwLock::new(InMemSignerInner {
222                keys: BTreeMap::from_iter(input),
223                #[cfg(with_getrandom)]
224                rng_state: RngState::new(None),
225            })))
226        }
227    }
228
229    impl Default for InMemSignerInner {
230        fn default() -> Self {
231            #[cfg(with_getrandom)]
232            let signer = InMemSignerInner::new(None);
233            #[cfg(not(with_getrandom))]
234            let signer = InMemSignerInner::new();
235            signer
236        }
237    }
238
239    impl Serialize for InMemorySigner {
240        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
241        where
242            S: serde::Serializer,
243        {
244            let inner = self.0.read().unwrap();
245            InMemSignerInner::serialize(&*inner, serializer)
246        }
247    }
248
249    impl<'de> Deserialize<'de> for InMemorySigner {
250        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
251        where
252            D: serde::Deserializer<'de>,
253        {
254            let inner = InMemSignerInner::deserialize(deserializer)?;
255            Ok(InMemorySigner(Arc::new(RwLock::new(inner))))
256        }
257    }
258
259    impl Serialize for InMemSignerInner {
260        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
261        where
262            S: serde::Serializer,
263        {
264            #[cfg(with_getrandom)]
265            let prng_seed = self.rng_state.testing_seed;
266
267            let keys_as_strings = self
268                .keys()
269                .into_iter()
270                .map(|(owner, bytes)| (owner, hex::encode(bytes)))
271                .collect::<Vec<_>>();
272
273            let inner = Inner {
274                keys: keys_as_strings,
275                #[cfg(with_getrandom)]
276                prng_seed,
277            };
278
279            Inner::serialize(&inner, serializer)
280        }
281    }
282
283    impl<'de> Deserialize<'de> for InMemSignerInner {
284        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
285        where
286            D: serde::Deserializer<'de>,
287        {
288            let inner = Inner::deserialize(deserializer)?;
289
290            let keys = inner
291                .keys
292                .into_iter()
293                .map(|(owner, secret_hex)| {
294                    let secret_bytes =
295                        hex::decode(&secret_hex).map_err(serde::de::Error::custom)?;
296                    let secret =
297                        serde_json::from_slice(&secret_bytes).map_err(serde::de::Error::custom)?;
298                    Ok((owner, secret))
299                })
300                .collect::<Result<BTreeMap<_, _>, _>>()?;
301
302            let signer = InMemSignerInner {
303                keys,
304                #[cfg(with_getrandom)]
305                rng_state: RngState::new(inner.prng_seed),
306            };
307            Ok(signer)
308        }
309    }
310}
linera_base/crypto/signer.rs

linera_base/crypto/
signer.rs
