Struct matrix_sdk::encryption::identities::Device

source ·

pub struct Device { /* private fields */ }

Available on crate feature e2e-encryption only.

Expand description

A device represents a E2EE capable client or device of an user.

A Device is backed by device keys that are uploaded to the server.

The device keys for our own device will be automatically uploaded by the SDK and the private parts of our device keys never leave this device.

Device keys consist of an Ed25519 keypair and a Curve25519 keypair. Only the public parts of those keypairs will be uploaded to the server.

                ┌──────────────────────────────────┐
                │              Device              │
                ├──────────────────────────────────┤
                │            Device Keys           │
                ├────────────────┬─────────────────┤
                │   Ed25519 Key  │  Curve25519 Key │
                └────────────────┴─────────────────┘

The Ed25519 key will be used to uniquely identify the Device while the Curve25519 key is used to establish 1-to-1 encrypted communication channels between two devices.

Implementations§

source §

impl Device

source

pub async fn request_verification(&self) -> Result<VerificationRequest>

Request an interactive verification with this Device.

Returns a VerificationRequest object that can be used to control the verification flow.

The default methods that are supported are m.sas.v1 and m.qr_code.show.v1, if this isn’t desirable the request_verification_with_methods() method can be used to override this. m.qr_code.show.v1 is only available if the qrcode feature is enabled, which it is by default.

§Examples

let device =
    client.encryption().get_device(alice, device_id!("DEVICEID")).await?;

if let Some(device) = device {
    let verification = device.request_verification().await?;
}

source

pub async fn request_verification_with_methods( &self, methods: Vec<VerificationMethod>, ) -> Result<VerificationRequest>

Request an interactive verification with this Device.

Returns a VerificationRequest object that can be used to control the verification flow.

§Arguments

methods - The verification methods that we want to support. Must be non-empty.

§Panics

This method will panic if methods is empty.

§Examples

let device =
    client.encryption().get_device(alice, device_id!("DEVICEID")).await?;

// We don't want to support showing a QR code, we only support SAS
// verification
let methods = vec![VerificationMethod::SasV1];

if let Some(device) = device {
    let verification =
        device.request_verification_with_methods(methods).await?;
}

source

pub async fn start_verification(&self) -> Result<SasVerification>

👎Deprecated since 0.4.0: directly starting a verification is deprecated in the spec. Users should instead use request_verification()

Start an interactive verification with this Device

Returns a SasVerification object that represents the interactive verification flow.

This method has been deprecated in the spec and the request_verification() method should be used instead.

§Examples

let device =
    client.encryption().get_device(alice, device_id!("DEVICEID")).await?;

if let Some(device) = device {
    let verification = device.start_verification().await?;
}

source

pub async fn verify(&self) -> Result<(), ManualVerifyError>

Manually verify this device.

This method will attempt to sign the device using our private cross signing key.

This method will always fail if the device belongs to someone else, we can only sign our own devices.

It can also fail if we don’t have the private part of our self-signing key.

The state of our private cross signing keys can be inspected using the Encryption::cross_signing_status() method.

§Problems of manual verification

Manual verification may be more convenient to use, i.e. both devices need to be online and available to interactively verify each other. Despite the convenience, interactive verifications should be generally preferred. Manually verifying a device won’t notify the other device, the one being verified, that they should also verify us. This means that device A will consider device B to be verified, but not the other way around.

§Examples

let device =
    client.encryption().get_device(alice, device_id!("DEVICEID")).await?;

if let Some(device) = device {
    device.verify().await?;
}

source

pub fn is_verified(&self) -> bool

Is the device considered to be verified.

A device is considered to be verified, either if it’s locally marked as such, or if it’s signed by the appropriate cross signing key. Our own device, is always implicitly verified.

§Local trust

Local trust can be established using the Device::set_local_trust() method or it will be established if we interactively verify the device using Device::request_verification().

Note: The concept of local trust is largely deprecated because it can’t be shared with other devices. Every device needs to verify all the other devices it communicates to. Because this becomes quickly unsustainable verification has migrated to cross signing verification.

§Cross signing verification

Cross signing verification uses signatures over devices and user identities to check if a device is considered to be verified. The signatures can be uploaded to the homeserver, this allows us to share the verification state with other devices. Devices only need to verify a user identity, if the user identity has verified and signed the device we can consider the device to be verified as well.

Devices are usually cross signing verified using interactive verification, which can be started using the Device::request_verification() method.

A Device can also be manually signed using the Device::verify() method, this works only for devices belonging to our own user.

Do note that the device that is being manually signed will not trust our own user identity like it would if we interactively verify the device. Such a device can mark our own user as verified using the UserIdentity::verify() method.

§Verification of devices belonging to our own user.

If the device belongs to our own user, the device will be considered to be verified if:

The device has been signed by our self-signing key
Our own user identity is considered to be verified

In other words we need to find a valid signature chain from our user identity to the device:

         ┌─────────────────────────────────────┐    ┌─────────────┐
         │           Own User Identity         │    │   Device    │
         ├──────────────────┬──────────────────┤───►├─────────────┤
         │    Master Key    │ Self-signing Key │    │ Device Keys │
         └──────────────────┴──────────────────┘    └─────────────┘

§Verification of devices belonging to other users.

If the device belongs to some other user it will be considered to be verified if:

The device has been signed by the user’s self-signing key
The user’s master-signing key has been signed by our own user-signing key, i.e. our own identity trusts the other users identity.
Our own user identity is considered to be verified

            ┌─────────────────────────────────────┐
            │           Own User Identity         │
            ├──────────────────┬──────────────────┤─────┐
            │    Master Key    │ User-signing Key │     │
            └──────────────────┴──────────────────┘     │
    ┌───────────────────────────────────────────────────┘
    │
    │       ┌─────────────────────────────────────┐    ┌─────────────┐
    │       │             User Identity           │    │   Device    │
    └──────►├──────────────────┬──────────────────┤───►│─────────────│
            │    Master Key    │ Self-signing Key │    │ Device Keys │
            └──────────────────┴──────────────────┘    └─────────────┘

§Examples

Let’s check if a device is verified:

let device =
    client.encryption().get_device(alice, device_id!("DEVICEID")).await?;

if let Some(device) = device {
    if device.is_verified() {
        println!(
            "Device {} of user {} is verified",
            device.device_id(),
            device.user_id(),
        );
    } else {
        println!(
            "Device {} of user {} is not verified",
            device.device_id(),
            device.user_id(),
        );
    }
}

source

pub fn is_verified_with_cross_signing(&self) -> bool

Is the device considered to be verified with cross-signing.

A device is considered to be verified if it’s signed by the appropriate cross-signing key.

§Cross-signing verification

Cross-signing verification uses signatures over devices and user identities to check if a device is considered to be verified. The signatures can be uploaded to the homeserver, this allows us to share the verification state with other devices. Devices only need to verify a user identity, if the user identity has verified and signed the device we can consider the device to be verified as well.

Devices are usually cross-signing verified using interactive verification, which can be started using the Device::request_verification() method.

A Device can also be manually signed using the Device::verify() method, this works only for devices belonging to our own user.

Do note that the device that is being manually signed will not trust our own user identity like it would if we interactively verify the device. Such a device can mark our own user as verified using the UserIdentity::verify() method.

§Verification of devices belonging to our own user.

If the device belongs to our own user, the device will be considered to be verified if:

The device has been signed by our self-signing key
Our own user identity is considered to be verified

In other words we need to find a valid signature chain from our user identity to the device:

         ┌─────────────────────────────────────┐    ┌─────────────┐
         │           Own User Identity         │    │   Device    │
         ├──────────────────┬──────────────────┤───►├─────────────┤
         │    Master Key    │ Self-signing Key │    │ Device Keys │
         └──────────────────┴──────────────────┘    └─────────────┘

§Verification of devices belonging to other users.

If the device belongs to some other user it will be considered to be verified if:

The device has been signed by the user’s self-signing key
The user’s master-signing key has been signed by our own user-signing key, i.e. our own identity trusts the other users identity.
Our own user identity is considered to be verified

            ┌─────────────────────────────────────┐
            │           Own User Identity         │
            ├──────────────────┬──────────────────┤─────┐
            │    Master Key    │ User-signing Key │     │
            └──────────────────┴──────────────────┘     │
    ┌───────────────────────────────────────────────────┘
    │
    │       ┌─────────────────────────────────────┐    ┌─────────────┐
    │       │             User Identity           │    │   Device    │
    └──────►├──────────────────┬──────────────────┤───►│─────────────│
            │    Master Key    │ Self-signing Key │    │ Device Keys │
            └──────────────────┴──────────────────┘    └─────────────┘

§Examples

Let’s check if a device is verified:

let device =
    client.encryption().get_device(alice, device_id!("DEVICEID")).await?;

if let Some(device) = device {
    if device.is_verified_with_cross_signing() {
        println!(
            "Device {} of user {} is verified with cross-signing",
            device.device_id(),
            device.user_id()
        );
    } else {
        println!(
            "Device {} of user {} is not verified with cross-signing",
            device.device_id(),
            device.user_id()
        );
    }
}