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crypto: Implement the whole SAS flow.

master
Damir Jelić 2020-07-23 13:41:57 +02:00
parent b1ae5534a1
commit bb9adea5de
1 changed files with 206 additions and 54 deletions
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260
matrix_sdk_crypto/src/verification/sas.rs
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@ -13,6 +13,7 @@
// limitations under the License.
use std::collections::BTreeMap;
use std::convert::TryInto;
use std::mem;
use crate::{Account, Device};
@ -24,7 +25,7 @@ use matrix_sdk_common::events::{
key::verification::{
accept::AcceptEventContent,
key::KeyEventContent,
mac::{MacEvent, MacEventContent},
mac::MacEventContent,
start::{MSasV1Content, MSasV1ContentOptions, StartEventContent},
HashAlgorithm, KeyAgreementProtocol, MessageAuthenticationCode, ShortAuthenticationString,
VerificationMethod,
@ -70,6 +71,10 @@ impl<S> Sas<S> {
pub fn user_id(&self) -> &UserId {
&self.ids.account.user_id()
}
pub fn device_id(&self) -> &DeviceId {
&self.ids.account.device_id()
}
}
fn get_emoji(index: u8) -> (&'static str, &'static str) {
@ -298,6 +303,57 @@ struct KeyReceived {
accepted_protocols: AcceptedProtocols,
}
fn receive_mac_event(
sas: &OlmSas,
ids: &SasIds,
flow_id: &str,
event: &ToDeviceEvent<MacEventContent>,
) -> (Vec<Box<DeviceId>>, Vec<String>) {
let mut verified_devices: Vec<Box<DeviceId>> = Vec::new();
let info = extra_mac_info_receive(&ids, flow_id);
let mut keys = event.content.mac.keys().cloned().collect::<Vec<String>>();
keys.sort();
let keys = sas
.calculate_mac(&keys.join(","), &format!("{}KEYIDS", &info))
.expect("Can't calculate SAS MAC");
if keys != event.content.keys {
panic!("Keys mac mismatch")
}
for (key_id, key_mac) in &event.content.mac {
let split: Vec<&str> = key_id.splitn(2, ":").collect();
if split.len() != 2 {
continue;
}
let algorithm: KeyAlgorithm = if let Ok(a) = split[0].try_into() {
a
} else {
continue;
};
let id = split[1];
let device_key_id = AlgorithmAndDeviceId(algorithm, id.into());
if let Some(key) = ids.other_device.keys().get(&device_key_id) {
if key_mac
== &sas
.calculate_mac(key, &format!("{}{}", info, key_id))
.expect("Can't calculate SAS MAC")
{
verified_devices.push(ids.other_device.device_id().into());
}
}
// TODO add an else branch for the master key here
}
(verified_devices, vec![])
}
impl Sas<KeyReceived> {
fn get_key_content(&self) -> KeyEventContent {
KeyEventContent {
@ -368,19 +424,36 @@ impl Sas<KeyReceived> {
.map(|b| b as u32)
.collect();
let first = (bytes[0] << 5 | bytes[1] >> 3) + 1000;
let second = ((bytes[1] & 0x7) << 10 | bytes[2] << 2 | bytes[3] >> 6) + 1000;
let third = ((bytes[3] & 0x3F) << 7 | bytes[4] >> 1) + 1000;
let first = bytes[0] << 5 | bytes[1] >> 3;
let second = (bytes[1] & 0x7) << 10 | bytes[2] << 2 | bytes[3] >> 6;
let third = (bytes[3] & 0x3F) << 7 | bytes[4] >> 1;
(first, second, third)
(first + 1000, second + 1000, third + 1000)
}
fn into_mac_received(self, event: &MacEvent) -> Sas<MacReceived> {
todo!()
fn into_mac_received(self, event: &ToDeviceEvent<MacEventContent>) -> Sas<MacReceived> {
let (devices, master_keys) =
receive_mac_event(&self.inner, &self.ids, &self.verification_flow_id, event);
Sas {
inner: self.inner,
verification_flow_id: self.verification_flow_id,
ids: self.ids,
state: MacReceived {
verified_devices: devices,
verified_master_keys: master_keys,
},
}
}
fn confirm(self) -> Sas<Confirmed> {
todo!()
Sas {
inner: self.inner,
verification_flow_id: self.verification_flow_id,
ids: self.ids,
state: Confirmed {
accepted_protocols: self.state.accepted_protocols,
},
}
}
}
@ -388,72 +461,118 @@ struct Confirmed {
accepted_protocols: AcceptedProtocols,
}
impl Sas<Confirmed> {
fn into_done(self, event: &MacEvent) -> Sas<Done> {
todo!()
}
fn extra_mac_info_send(ids: &SasIds, flow_id: &str) -> String {
format!(
"MATRIX_KEY_VERIFICATION_MAC{first_user}{first_device}\
{second_user}{second_device}{transaction_id}",
first_user = ids.account.user_id(),
first_device = ids.account.device_id(),
second_user = ids.other_device.user_id(),
second_device = ids.other_device.device_id(),
transaction_id = flow_id,
)
}
fn get_mac_info(&self) -> String {
format!(
"MATRIX_KEY_VERIFICATION_MAC{first_user}{first_device}\
{second_user}{second_device}{transaction_id}",
first_user = self.ids.account.user_id(),
first_device = self.ids.account.device_id(),
second_user = self.ids.other_device.user_id(),
second_device = self.ids.other_device.device_id(),
transaction_id = self.verification_flow_id,
)
fn extra_mac_info_receive(ids: &SasIds, flow_id: &str) -> String {
format!(
"MATRIX_KEY_VERIFICATION_MAC{first_user}{first_device}\
{second_user}{second_device}{transaction_id}",
first_user = ids.other_device.user_id(),
first_device = ids.other_device.device_id(),
second_user = ids.account.user_id(),
second_device = ids.account.device_id(),
transaction_id = flow_id,
)
}
fn get_mac_content(sas: &OlmSas, ids: &SasIds, flow_id: &str) -> MacEventContent {
let mut mac: BTreeMap<String, String> = BTreeMap::new();
let key_id = AlgorithmAndDeviceId(KeyAlgorithm::Ed25519, ids.account.device_id().into());
let key = ids.account.identity_keys().ed25519();
let info = extra_mac_info_send(ids, flow_id);
mac.insert(
key_id.to_string(),
sas.calculate_mac(key, &format!("{}{}", info, key_id))
.expect("Can't calculate SAS MAC"),
);
// TODO Add the cross signing master key here if we trust/have it.
let mut keys = mac.keys().cloned().collect::<Vec<String>>();
keys.sort();
let keys = sas
.calculate_mac(&keys.join(","), &format!("{}KEYIDS", &info))
.expect("Can't calculate SAS MAC");
MacEventContent {
transaction_id: flow_id.to_owned(),
keys,
mac,
}
}
impl Sas<Confirmed> {
fn into_done(self, event: &ToDeviceEvent<MacEventContent>) -> Sas<Done> {
let (devices, master_keys) =
receive_mac_event(&self.inner, &self.ids, &self.verification_flow_id, event);
Sas {
inner: self.inner,
verification_flow_id: self.verification_flow_id,
ids: self.ids,
state: Done {
verified_devices: devices,
verified_master_keys: master_keys,
},
}
}
fn get_mac_event_content(&self) -> MacEventContent {
let mut mac: BTreeMap<String, String> = BTreeMap::new();
let info = self.get_mac_info();
let key_id =
AlgorithmAndDeviceId(KeyAlgorithm::Ed25519, self.ids.account.device_id().into());
let key = self.ids.account.identity_keys().ed25519();
mac.insert(
key_id.to_string(),
self.inner
.calculate_mac(key, &format!("{}{}", info, key_id))
.expect("Can't calculate SAS MAC"),
);
// TODO Add the cross signing master key here if we trust/have it.
let mut keys = mac.keys().cloned().collect::<Vec<String>>();
keys.sort();
let keys = self
.inner
.calculate_mac(&keys.join(","), &format!("{}KEYIDS", &info))
.expect("Can't calculate SAS MAC");
MacEventContent {
transaction_id: self.verification_flow_id.clone(),
keys,
mac,
}
get_mac_content(&self.inner, &self.ids, &self.verification_flow_id)
}
}
struct MacReceived {
verified_devices: Vec<String>,
verified_devices: Vec<Box<DeviceId>>,
verified_master_keys: Vec<String>,
}
impl Sas<MacReceived> {
fn confirm(self) -> Sas<Done> {
todo!()
Sas {
inner: self.inner,
verification_flow_id: self.verification_flow_id,
ids: self.ids,
state: Done {
verified_devices: self.state.verified_devices,
verified_master_keys: self.state.verified_master_keys,
},
}
}
}
struct Done {
verified_devices: Vec<String>,
verified_devices: Vec<Box<DeviceId>>,
verified_master_keys: Vec<String>,
}
impl Sas<Done> {
fn get_mac_event_content(&self) -> MacEventContent {
get_mac_content(&self.inner, &self.ids, &self.verification_flow_id)
}
fn verified_devices(&self) -> &Vec<Box<DeviceId>> {
&self.state.verified_devices
}
fn verified_master_keys(&self) -> &[String] {
&self.state.verified_master_keys
}
}
#[cfg(test)]
mod test {
use std::convert::TryFrom;
@ -536,4 +655,37 @@ mod test {
assert_eq!(alice.get_decimal(), bob.get_decimal());
assert_eq!(alice.get_emoji(), bob.get_emoji());
}
#[tokio::test]
async fn sas_mac() {
let (alice, bob) = get_sas_pair().await;
let event = wrap_to_device_event(bob.user_id(), bob.get_accept_content());
let alice: Sas<Accepted> = alice.into_accepted(&event);
let mut event = wrap_to_device_event(alice.user_id(), alice.get_key_content());
let bob = bob.into_key_received(&mut event);
let mut event = wrap_to_device_event(bob.user_id(), bob.get_key_content());
let alice = alice.into_key_received(&mut event);
assert_eq!(alice.get_decimal(), bob.get_decimal());
assert_eq!(alice.get_emoji(), bob.get_emoji());
let bob = bob.confirm();
let event = wrap_to_device_event(bob.user_id(), bob.get_mac_event_content());
let alice = alice.into_mac_received(&event);
// assert!(!alice.get_emoji().is_empty());
let alice = alice.confirm();
let event = wrap_to_device_event(alice.user_id(), alice.get_mac_event_content());
let bob = bob.into_done(&event);
assert!(bob.verified_devices().contains(&alice.device_id().into()));
assert!(alice.verified_devices().contains(&bob.device_id().into()));
}
}