af_keys/
multisig.rs

1// Copyright (c) Mysten Labs, Inc.
2// SPDX-License-Identifier: Apache-2.0
3
4use std::hash::{Hash, Hasher};
5use std::str::FromStr;
6
7use af_sui_types::Address as SuiAddress;
8pub use enum_dispatch::enum_dispatch;
9use fastcrypto::encoding::{Base64, Encoding};
10use fastcrypto::error::FastCryptoError;
11use fastcrypto::hash::HashFunction as _;
12use fastcrypto::traits::ToFromBytes;
13use once_cell::sync::OnceCell;
14use serde::{Deserialize, Serialize};
15use serde_with::serde_as;
16
17use crate::crypto::{
18    CompressedSignature,
19    DefaultHash,
20    Error,
21    PublicKey,
22    Signature,
23    SignatureScheme,
24};
25
26pub type WeightUnit = u8;
27pub type ThresholdUnit = u16;
28pub type BitmapUnit = u16;
29pub const MAX_SIGNER_IN_MULTISIG: usize = 10;
30pub const MAX_BITMAP_VALUE: BitmapUnit = 0b1111111111;
31
32// =============================================================================
33//  MultiSigSigner
34// =============================================================================
35
36/// Data needed for signing as a multisig.
37#[derive(Deserialize, Debug)]
38pub struct MultiSigSigner {
39    pub multisig_pk: MultiSigPublicKey,
40    /// The indexes of the public keys in `multisig_pk` to sign for.
41    pub signers: Vec<usize>,
42}
43
44// =============================================================================
45//  MultiSig
46// =============================================================================
47
48/// The struct that contains signatures and public keys necessary for authenticating a MultiSig.
49#[serde_as]
50#[derive(Debug, Serialize, Deserialize, Clone)]
51pub struct MultiSig {
52    /// The plain signature encoded with signature scheme.
53    sigs: Vec<CompressedSignature>,
54    /// A bitmap that indicates the position of which public key the signature should be authenticated with.
55    bitmap: BitmapUnit,
56    /// The public key encoded with each public key with its signature scheme used along with the corresponding weight.
57    multisig_pk: MultiSigPublicKey,
58    /// A bytes representation of [struct MultiSig]. This helps with implementing [trait AsRef<[u8]>].
59    #[serde(skip)]
60    bytes: OnceCell<Vec<u8>>,
61}
62
63impl MultiSig {
64    /// This combines a list of [enum Signature] `flag || signature || pk` to a MultiSig.
65    /// The order of full_sigs must be the same as the order of public keys in
66    /// [enum MultiSigPublicKey]. e.g. for [pk1, pk2, pk3, pk4, pk5],
67    /// [sig1, sig2, sig5] is valid, but [sig2, sig1, sig5] is invalid.
68    pub fn combine(
69        full_sigs: Vec<Signature>,
70        multisig_pk: MultiSigPublicKey,
71    ) -> Result<Self, Error> {
72        multisig_pk
73            .validate()
74            .map_err(|_| Error::InvalidSignature {
75                error: "Invalid multisig public key".to_string(),
76            })?;
77
78        if full_sigs.len() > multisig_pk.pk_map.len() || full_sigs.is_empty() {
79            return Err(Error::InvalidSignature {
80                error: "Invalid number of signatures".to_string(),
81            });
82        }
83        let mut bitmap = 0;
84        let mut sigs = Vec::with_capacity(full_sigs.len());
85        for s in full_sigs {
86            let pk = s.to_public_key()?;
87            let index = multisig_pk
88                .get_index(&pk)
89                .ok_or_else(|| Error::IncorrectSigner {
90                    error: format!("pk does not exist: {pk:?}"),
91                })?;
92            if bitmap & (1 << index) != 0 {
93                return Err(Error::InvalidSignature {
94                    error: "Duplicate public key".to_string(),
95                });
96            }
97            bitmap |= 1 << index;
98            sigs.push(s.to_compressed()?);
99        }
100
101        Ok(Self {
102            sigs,
103            bitmap,
104            multisig_pk,
105            bytes: OnceCell::new(),
106        })
107    }
108
109    pub fn init_and_validate(&self) -> Result<Self, FastCryptoError> {
110        if self.sigs.len() > self.multisig_pk.pk_map.len()
111            || self.sigs.is_empty()
112            || self.bitmap > MAX_BITMAP_VALUE
113        {
114            return Err(FastCryptoError::InvalidInput);
115        }
116        self.multisig_pk.validate()?;
117        Ok(self.to_owned())
118    }
119
120    pub const fn get_pk(&self) -> &MultiSigPublicKey {
121        &self.multisig_pk
122    }
123
124    pub fn get_sigs(&self) -> &[CompressedSignature] {
125        &self.sigs
126    }
127
128    pub fn get_indices(&self) -> Result<Vec<u8>, Error> {
129        as_indices(self.bitmap)
130    }
131}
132
133/// Necessary trait for [struct SenderSignedData].
134impl PartialEq for MultiSig {
135    fn eq(&self, other: &Self) -> bool {
136        self.sigs == other.sigs
137            && self.bitmap == other.bitmap
138            && self.multisig_pk == other.multisig_pk
139    }
140}
141
142/// Necessary trait for [struct SenderSignedData].
143impl Eq for MultiSig {}
144
145/// Necessary trait for [struct SenderSignedData].
146impl Hash for MultiSig {
147    fn hash<H: Hasher>(&self, state: &mut H) {
148        self.as_ref().hash(state);
149    }
150}
151
152/// Interpret a bitmap of 01s as a list of indices that is set to 1s.
153/// e.g. 22 = 0b10110, then the result is [1, 2, 4].
154pub fn as_indices(bitmap: u16) -> Result<Vec<u8>, Error> {
155    if bitmap > MAX_BITMAP_VALUE {
156        return Err(Error::InvalidSignature {
157            error: "Invalid bitmap".to_string(),
158        });
159    }
160    let mut res = Vec::new();
161    for i in 0..10 {
162        if bitmap & (1 << i) != 0 {
163            res.push(i as u8);
164        }
165    }
166    Ok(res)
167}
168
169impl ToFromBytes for MultiSig {
170    fn from_bytes(bytes: &[u8]) -> Result<Self, FastCryptoError> {
171        // The first byte matches the flag of MultiSig.
172        if bytes.first().ok_or(FastCryptoError::InvalidInput)? != &SignatureScheme::MultiSig.flag()
173        {
174            return Err(FastCryptoError::InvalidInput);
175        }
176        let multisig: Self =
177            bcs::from_bytes(&bytes[1..]).map_err(|_| FastCryptoError::InvalidSignature)?;
178        multisig.init_and_validate()
179    }
180}
181
182impl FromStr for MultiSig {
183    type Err = Error;
184
185    fn from_str(s: &str) -> Result<Self, Self::Err> {
186        let bytes = Base64::decode(s).map_err(|_| Error::InvalidSignature {
187            error: "Invalid base64 string".to_string(),
188        })?;
189        let sig = Self::from_bytes(&bytes).map_err(|_| Error::InvalidSignature {
190            error: "Invalid multisig bytes".to_string(),
191        })?;
192        Ok(sig)
193    }
194}
195
196/// This initialize the underlying bytes representation of MultiSig. It encodes
197/// [struct MultiSig] as the MultiSig flag (0x03) concat with the bcs bytes
198/// of [struct MultiSig] i.e. `flag || bcs_bytes(MultiSig)`.
199impl AsRef<[u8]> for MultiSig {
200    fn as_ref(&self) -> &[u8] {
201        self.bytes
202            .get_or_try_init::<_, eyre::Report>(|| {
203                let as_bytes = bcs::to_bytes(self).expect("BCS serialization should not fail");
204                let mut bytes = Vec::with_capacity(1 + as_bytes.len());
205                bytes.push(SignatureScheme::MultiSig.flag());
206                bytes.extend_from_slice(as_bytes.as_slice());
207                Ok(bytes)
208            })
209            .expect("OnceCell invariant violated")
210    }
211}
212
213impl From<MultiSig> for af_sui_types::UserSignature {
214    fn from(value: MultiSig) -> Self {
215        Self::from_bytes(value.as_bytes()).expect("Compatible")
216    }
217}
218
219// =============================================================================
220//  MultiSigPublicKey
221// =============================================================================
222
223/// The struct that contains the public key used for authenticating a MultiSig.
224#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
225pub struct MultiSigPublicKey {
226    /// A list of public key and its corresponding weight.
227    pk_map: Vec<(PublicKey, WeightUnit)>,
228    /// If the total weight of the public keys corresponding to verified signatures is larger than threshold, the MultiSig is verified.
229    threshold: ThresholdUnit,
230}
231
232impl MultiSigPublicKey {
233    /// Construct MultiSigPublicKey without validation.
234    #[expect(
235        clippy::missing_const_for_fn,
236        reason = "Don't want to risk breaking the API if this uses a non-const init in the future"
237    )]
238    pub fn insecure_new(pk_map: Vec<(PublicKey, WeightUnit)>, threshold: ThresholdUnit) -> Self {
239        Self { pk_map, threshold }
240    }
241
242    pub fn new(
243        pks: Vec<PublicKey>,
244        weights: Vec<WeightUnit>,
245        threshold: ThresholdUnit,
246    ) -> Result<Self, Error> {
247        if pks.is_empty()
248            || weights.is_empty()
249            || threshold == 0
250            || pks.len() != weights.len()
251            || pks.len() > MAX_SIGNER_IN_MULTISIG
252            || weights.iter().any(|w| *w == 0)
253            || weights
254                .iter()
255                .map(|w| *w as ThresholdUnit)
256                .sum::<ThresholdUnit>()
257                < threshold
258            || pks
259                .iter()
260                .enumerate()
261                .any(|(i, pk)| pks.iter().skip(i + 1).any(|other_pk| *pk == *other_pk))
262        {
263            return Err(Error::InvalidSignature {
264                error: "Invalid multisig public key construction".to_string(),
265            });
266        }
267
268        Ok(Self {
269            pk_map: pks.into_iter().zip(weights).collect(),
270            threshold,
271        })
272    }
273
274    pub fn get_index(&self, pk: &PublicKey) -> Option<u8> {
275        self.pk_map.iter().position(|x| &x.0 == pk).map(|x| x as u8)
276    }
277
278    pub const fn threshold(&self) -> &ThresholdUnit {
279        &self.threshold
280    }
281
282    pub const fn pubkeys(&self) -> &Vec<(PublicKey, WeightUnit)> {
283        &self.pk_map
284    }
285
286    pub fn validate(&self) -> Result<Self, FastCryptoError> {
287        let pk_map = self.pubkeys();
288        if self.threshold == 0
289            || pk_map.is_empty()
290            || pk_map.len() > MAX_SIGNER_IN_MULTISIG
291            || pk_map.iter().any(|(_pk, weight)| *weight == 0)
292            || pk_map
293                .iter()
294                .map(|(_pk, weight)| *weight as ThresholdUnit)
295                .sum::<ThresholdUnit>()
296                < self.threshold
297            || pk_map.iter().enumerate().any(|(i, (pk, _weight))| {
298                pk_map
299                    .iter()
300                    .skip(i + 1)
301                    .any(|(other_pk, _weight)| *pk == *other_pk)
302            })
303        {
304            return Err(FastCryptoError::InvalidInput);
305        }
306        Ok(self.to_owned())
307    }
308}
309
310impl From<&MultiSigPublicKey> for SuiAddress {
311    /// Derive a SuiAddress from [struct MultiSigPublicKey]. A MultiSig address
312    /// is defined as the 32-byte Blake2b hash of serializing the flag, the
313    /// threshold, concatenation of all n flag, public keys and
314    /// its weight. `flag_MultiSig || threshold || flag_1 || pk_1 || weight_1
315    /// || ... || flag_n || pk_n || weight_n`.
316    ///
317    /// When flag_i is ZkLogin, pk_i refers to [struct ZkLoginPublicIdentifier]
318    /// derived from padded address seed in bytes and iss.
319    fn from(multisig_pk: &MultiSigPublicKey) -> Self {
320        let mut hasher = DefaultHash::default();
321        hasher.update([SignatureScheme::MultiSig.flag()]);
322        hasher.update(multisig_pk.threshold().to_le_bytes());
323        multisig_pk.pubkeys().iter().for_each(|(pk, w)| {
324            hasher.update([pk.flag()]);
325            hasher.update(pk.as_ref());
326            hasher.update(w.to_le_bytes());
327        });
328        Self::new(hasher.finalize().digest)
329    }
330}
af_keys/multisig.rs

af_keys/
multisig.rs
