matrix_sdk_crypto/types/cross_signing/
master.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
// Copyright 2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::collections::btree_map::Iter;

use ruma::{encryption::KeyUsage, DeviceKeyId, OwnedDeviceKeyId, UserId};
use serde::{Deserialize, Serialize};
use vodozemac::Ed25519PublicKey;

use super::{CrossSigningKey, CrossSigningSubKeys, SigningKey};
use crate::{
    olm::VerifyJson,
    types::{Signatures, SigningKeys},
    SignatureError,
};

/// Wrapper for a cross signing key marking it as the master key.
///
/// Master keys are used to sign other cross signing keys, the self signing and
/// user signing keys of an user will be signed by their master key.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(try_from = "CrossSigningKey")]
pub struct MasterPubkey(pub(super) CrossSigningKey);

impl MasterPubkey {
    /// Get the user id of the master key's owner.
    pub fn user_id(&self) -> &UserId {
        &self.0.user_id
    }

    /// Get the keys map of containing the master keys.
    pub fn keys(&self) -> &SigningKeys<OwnedDeviceKeyId> {
        &self.0.keys
    }

    /// Get the list of `KeyUsage` that is set for this key.
    pub fn usage(&self) -> &[KeyUsage] {
        &self.0.usage
    }

    /// Get the signatures map of this cross signing key.
    pub fn signatures(&self) -> &Signatures {
        &self.0.signatures
    }

    /// Get the master key with the given key id.
    ///
    /// # Arguments
    ///
    /// * `key_id` - The id of the key that should be fetched.
    pub fn get_key(&self, key_id: &DeviceKeyId) -> Option<&SigningKey> {
        self.0.keys.get(key_id)
    }

    /// Get the first available master key.
    ///
    /// There's usually only a single master key so this will usually fetch the
    /// only key.
    pub fn get_first_key(&self) -> Option<Ed25519PublicKey> {
        self.0.get_first_key_and_id().map(|(_, k)| k)
    }

    /// Check if the given JSON is signed by this master key.
    ///
    /// This method should only be used if an object's signature needs to be
    /// checked multiple times, and you'd like to avoid performing the
    /// canonicalization step each time.
    ///
    /// **Note**: Use this method with caution, the `canonical_json` needs to be
    /// correctly canonicalized and make sure that the object you are checking
    /// the signature for is allowed to be signed by a master key.
    pub(crate) fn has_signed_raw(
        &self,
        signatures: &Signatures,
        canonical_json: &str,
    ) -> Result<(), SignatureError> {
        if let Some((key_id, key)) = self.0.get_first_key_and_id() {
            key.verify_canonicalized_json(&self.0.user_id, key_id, signatures, canonical_json)
        } else {
            Err(SignatureError::UnsupportedAlgorithm)
        }
    }

    /// Check if the given cross signing sub-key is signed by the master key.
    ///
    /// # Arguments
    ///
    /// * `subkey` - The subkey that should be checked for a valid signature.
    ///
    /// Returns an empty result if the signature check succeeded, otherwise a
    /// SignatureError indicating why the check failed.
    pub(crate) fn verify_subkey<'a>(
        &self,
        subkey: impl Into<CrossSigningSubKeys<'a>>,
    ) -> Result<(), SignatureError> {
        let subkey: CrossSigningSubKeys<'_> = subkey.into();

        if self.0.user_id != subkey.user_id() {
            return Err(SignatureError::UserIdMismatch);
        }

        if let Some((key_id, key)) = self.0.get_first_key_and_id() {
            key.verify_json(&self.0.user_id, key_id, subkey.cross_signing_key())
        } else {
            Err(SignatureError::UnsupportedAlgorithm)
        }
    }
}

impl<'a> IntoIterator for &'a MasterPubkey {
    type Item = (&'a OwnedDeviceKeyId, &'a SigningKey);
    type IntoIter = Iter<'a, OwnedDeviceKeyId, SigningKey>;

    fn into_iter(self) -> Self::IntoIter {
        self.keys().iter()
    }
}

impl AsRef<CrossSigningKey> for MasterPubkey {
    fn as_ref(&self) -> &CrossSigningKey {
        &self.0
    }
}

impl AsMut<CrossSigningKey> for MasterPubkey {
    fn as_mut(&mut self) -> &mut CrossSigningKey {
        &mut self.0
    }
}

impl TryFrom<CrossSigningKey> for MasterPubkey {
    type Error = serde_json::Error;

    fn try_from(key: CrossSigningKey) -> Result<Self, Self::Error> {
        if key.usage.contains(&KeyUsage::Master) && key.usage.len() == 1 {
            Ok(Self(key))
        } else {
            Err(serde::de::Error::custom(format!(
                "Expected cross signing key usage {} was not found",
                KeyUsage::Master
            )))
        }
    }
}