hopr_crypto_types/
keypairs.rs

1use std::fmt::Debug;
2
3use digest::Digest;
4use generic_array::{ArrayLength, GenericArray};
5use hopr_crypto_random::random_bytes;
6use hopr_primitive_types::prelude::*;
7use sha2::Sha512;
8use subtle::{Choice, ConstantTimeEq};
9
10use crate::{
11    errors,
12    errors::CryptoError::InvalidInputValue,
13    types::{OffchainPublicKey, PublicKey},
14    utils::{SecretValue, k256_scalar_from_bytes, random_group_element, x25519_scalar_from_bytes},
15};
16
17/// Represents a generic key pair
18/// The keypair contains a private key and public key.
19/// Must be comparable in constant time and zeroized on drop.
20pub trait Keypair: ConstantTimeEq + Sized {
21    /// Represents the type of the private (secret) key
22    type SecretLen: ArrayLength;
23
24    /// Represents the type of the public key
25    type Public: BytesRepresentable + Clone + PartialEq;
26
27    /// Generates a new random keypair.
28    fn random() -> Self;
29
30    /// Creates a keypair from the given secret key.
31    fn from_secret(bytes: &[u8]) -> errors::Result<Self>;
32
33    /// Returns the private (secret) part of the keypair
34    fn secret(&self) -> &SecretValue<Self::SecretLen>;
35
36    /// Returns the public part of the keypair
37    fn public(&self) -> &Self::Public;
38
39    /// Consumes the instance and produces separated private and public parts
40    fn unzip(self) -> (SecretValue<Self::SecretLen>, Self::Public) {
41        (self.secret().clone(), self.public().clone())
42    }
43}
44
45/// Represents a keypair consisting of an Ed25519 private and public key
46#[derive(Clone)]
47pub struct OffchainKeypair(SecretValue<typenum::U32>, OffchainPublicKey);
48
49impl Keypair for OffchainKeypair {
50    type Public = OffchainPublicKey;
51    type SecretLen = typenum::U32;
52
53    fn random() -> Self {
54        // Safe to unwrap here, as the random bytes length is exact
55        Self::from_secret(&random_bytes::<{ ed25519_dalek::SECRET_KEY_LENGTH }>()).unwrap()
56    }
57
58    fn from_secret(bytes: &[u8]) -> errors::Result<Self> {
59        Ok(Self(
60            bytes.try_into().map_err(|_| InvalidInputValue("bytes"))?,
61            OffchainPublicKey::from_privkey(bytes)?,
62        ))
63    }
64
65    fn secret(&self) -> &SecretValue<typenum::U32> {
66        &self.0
67    }
68
69    fn public(&self) -> &Self::Public {
70        &self.1
71    }
72}
73
74impl Debug for OffchainKeypair {
75    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
76        f.debug_tuple("OffchainKeypair").field(&self.1).finish()
77    }
78}
79
80impl ConstantTimeEq for OffchainKeypair {
81    fn ct_eq(&self, other: &Self) -> Choice {
82        self.secret().ct_eq(other.secret())
83    }
84}
85
86impl From<&OffchainKeypair> for curve25519_dalek::scalar::Scalar {
87    /// Transforms the secret to be equivalent with the EdDSA public key used for signing.
88    /// This is required so that the secret keys used to generate Sphinx shared secrets
89    /// correspond to the public keys we get from the Ed25519 peer ids.
90    fn from(value: &OffchainKeypair) -> Self {
91        let mut h: Sha512 = Sha512::default();
92        h.update(&value.0);
93        let hash = h.finalize();
94
95        let mut ret = [0u8; ed25519_dalek::SECRET_KEY_LENGTH];
96        ret.copy_from_slice(&hash[..32]);
97        x25519_scalar_from_bytes(&ret).unwrap() // cannot happen, secret always represents a valid scalar
98    }
99}
100
101impl From<&OffchainKeypair> for libp2p_identity::Keypair {
102    fn from(value: &OffchainKeypair) -> Self {
103        libp2p_identity::Keypair::ed25519_from_bytes(value.0.clone()).expect("invalid offchain keypair")
104        // must not happen
105    }
106}
107
108impl From<&OffchainKeypair> for libp2p_identity::PeerId {
109    fn from(value: &OffchainKeypair) -> Self {
110        value.1.into()
111    }
112}
113
114/// Represents a keypair consisting of a secp256k1 private and public key
115#[derive(Clone)]
116pub struct ChainKeypair(SecretValue<typenum::U32>, PublicKey);
117
118impl Keypair for ChainKeypair {
119    type Public = PublicKey;
120    type SecretLen = typenum::U32;
121
122    fn random() -> Self {
123        let (secret, public) = random_group_element();
124        Self(GenericArray::from(secret).into(), public.into())
125    }
126
127    fn from_secret(bytes: &[u8]) -> errors::Result<Self> {
128        let compressed = PublicKey::from_privkey(bytes)?;
129
130        Ok(Self(
131            bytes.try_into().map_err(|_| InvalidInputValue("bytes"))?,
132            compressed,
133        ))
134    }
135
136    fn secret(&self) -> &SecretValue<typenum::U32> {
137        &self.0
138    }
139
140    fn public(&self) -> &Self::Public {
141        &self.1
142    }
143}
144
145impl Debug for ChainKeypair {
146    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
147        // Do not expose the private key
148        f.debug_tuple("ChainKeypair").field(&self.1).finish()
149    }
150}
151
152impl ConstantTimeEq for ChainKeypair {
153    fn ct_eq(&self, other: &Self) -> Choice {
154        self.secret().ct_eq(other.secret())
155    }
156}
157
158impl From<&ChainKeypair> for k256::Scalar {
159    fn from(value: &ChainKeypair) -> Self {
160        k256_scalar_from_bytes(value.0.as_ref()).unwrap() // cannot happen, secret always represents a valid scalar
161    }
162}
163
164impl From<&ChainKeypair> for Address {
165    fn from(value: &ChainKeypair) -> Self {
166        value.public().to_address()
167    }
168}
169
170#[cfg(test)]
171mod tests {
172    use libp2p_identity::PeerId;
173    use subtle::ConstantTimeEq;
174
175    use super::*;
176
177    #[test]
178    fn test_offchain_keypair() {
179        let kp_1 = OffchainKeypair::random();
180
181        let public = OffchainPublicKey::from_privkey(kp_1.secret().as_ref()).unwrap();
182        assert_eq!(&public, kp_1.public(), "secret keys must yield compatible public keys");
183
184        let kp_2 = OffchainKeypair::from_secret(kp_1.secret().as_ref()).unwrap();
185        assert_eq!(
186            kp_1.ct_eq(&kp_2).unwrap_u8(),
187            1,
188            "keypairs generated from secrets must be equal"
189        );
190        assert_eq!(&public, kp_2.public(), "secret keys must yield compatible public keys");
191        assert_eq!(kp_1.public(), kp_2.public(), "keypair public keys must be equal");
192
193        let (s1, p1) = kp_1.unzip();
194        let (s2, p2) = kp_2.unzip();
195
196        assert_eq!(s1.ct_eq(&s2).unwrap_u8(), 1);
197        assert_eq!(p1, p2);
198    }
199
200    #[test]
201    fn test_offchain_keypair_libp2p_compatibility() {
202        let kp_1 = OffchainKeypair::random();
203
204        let p2p_kp: libp2p_identity::Keypair = (&kp_1).into();
205
206        let p1: PeerId = (*kp_1.public()).into();
207        let p2: PeerId = p2p_kp.public().into();
208        assert_eq!(p1, p2, "peer ids must be equal");
209    }
210
211    #[test]
212    fn test_chain_keypair() {
213        let kp_1 = ChainKeypair::random();
214
215        let public = PublicKey::from_privkey(kp_1.secret().as_ref()).unwrap();
216        assert_eq!(&public, kp_1.public(), "secret keys must yield compatible public keys");
217
218        let kp_2 = ChainKeypair::from_secret(kp_1.secret().as_ref()).unwrap();
219        assert_eq!(
220            kp_1.ct_eq(&kp_2).unwrap_u8(),
221            1,
222            "keypairs generated from secrets must be equal"
223        );
224        assert_eq!(&public, kp_2.public(), "secret keys must yield compatible public keys");
225        assert_eq!(kp_1.public(), kp_2.public(), "keypair public keys must be equal");
226
227        let (s1, p1) = kp_1.unzip();
228        let (s2, p2) = kp_2.unzip();
229
230        assert_eq!(s1.ct_eq(&s2).unwrap_u8(), 1);
231        assert_eq!(p1, p2);
232    }
233}
hopr_crypto_types/keypairs.rs

hopr_crypto_types/
keypairs.rs
