Note

This page is a work in progress. It may contain incomplete or incorrect information.

Identity Management¶

On-ledger identity management focuses on the distributed aspect of identities across Canton system entities, while user identity management focuses on individual participants managing access of their users to their ledger APIs.

Canton comes with a built-in identity management system used to manage on-ledger identities. The technical details are explained in the architecture section, while this write-up here is meant to give a high level explanation.

The identity management system is self-contained and built without a trusted central entity or pre-defined root certificate such that anyone can connect with anyone, without the need for some central approval and without the danger of losing self-sovereignty.

Introduction¶

What is a Canton Identity?¶

When two system entities such as a participant, synchronizer topology manager, mediator or sequencer communicate with each other, they will use asymmetric cryptography to encrypt messages and sign message contents such that only the recipient can decrypt the content, verify the authenticity of the message, or prove its origin. Therefore, we need a method to uniquely identify the system entities and a way to associate encryption and signing keys with them.

On top of that, Canton uses the contract language Daml, which represents contract ownership and rights through parties. But parties are not primary members of the Canton synchronization protocol. They are represented by participants and therefore we need to uniquely identify parties and relate them to participants, such that a participant can represent several parties (and in Canton, a party can be represented by several participants).

Unique Identifier¶

A Canton identity is built out of two components: a random string X and a fingerprint of a public key N. This combination, (X,N), is called a unique identifier and is assumed to be globally unique by design. This unique identifier is used in Canton to refer to particular parties, participants, or synchronizer entities. A system entity (such as a party) is described by the combination of role (party, participant, mediator, sequencer, synchronizer topology manager) and its unique identifier.

The system entities require knowledge about the keys that are used for encryption and signing by the respective other entities. This knowledge is distributed and therefore, the system entities require a way to verify that a certain association of an entity with a key is correct and valid. This is the purpose of the fingerprint of a public key in the unique identifier, which is referred to as Namespace. The secret key of the corresponding namespace acts as the root of trust for that particular namespace, as explained later.

Topology Transactions¶

In order to remain flexible and be able to change keys and cryptographic algorithms, we don’t identify the entities using a single static key, but we need a way to dynamically associate participants or synchronizer entities with keys and parties with participants. We do this through topology transactions.

A topology transaction establishes a certain association of a unique identifier with either a key or a relationship with another identifier. There are several different types of topology transactions. The most general one is the OwnerToKeyMapping, which as the name says, associates a key with a unique identifier. Such a topology transaction will inform all other system entities that a certain system entity is using a specific key for a specific purpose, such as participant Alice of namespace 12345.. is using the key identified through the fingerprint AABBCCDDEE.. to sign messages.

Now, this poses two questions: who authorizes these transactions, and who distributes them?

For the authorization, we need to look at the second part of the unique identifier, the Namespace. A topology transaction that refers to a particular unique identifier operates on that namespace and we require that such a topology transaction is authorized by the corresponding secret key through a cryptographic signature of the serialized topology transaction. This authorization can be either direct, if it is signed by the secret key of the namespace, or indirect, if it is signed by a delegated key. To delegate the signing right to another key, there are other topology transactions of type NamespaceDelegation or IdentifierDelegation that allow one to do that. A namespace delegation delegates entire namespaces to a certain key, such as saying the key identifier through the fingerprint AABBCCDDEE… is now allowed to authorize topology transactions within the namespace of the key VVWWXXYYZZ….

Signing of topology transactions happens in a TopologyManager. Canton has many topology managers. Every participant node and every synchronizer have topology managers with exactly the same functional capabilities, just different impacts. They can create new keys, new namespaces, and the identity of new participants, parties, and synchronizers. And they can export these topology transactions such that they can be imported by another topology manager. This allows you to manage Canton identities in quite a wide range of ways. A participant can operate their own topology manager which allows them individually to manage their parties. Or they can associate themselves with another topology manager and let them manage the parties that they represent or keys they use. Or something in between, depending on the introduced delegations and associations.

The difference between the synchronizer topology manager and the participant topology manager is that the synchronizer topology manager establishes the valid topology state in a particular synchronizer by distributing topology transactions in a way that every synchronizer member ends up with the same topology state. However, the synchronizer topology manager is just a gatekeeper of the synchronizer that decides who is let in and who is not on that particular synchronizer, but the actual topology statements originate from various sources. As such, the synchronizer topology manager can only block the distribution, but cannot fake topology transactions.

The participant topology manager only manages an isolated topology state. However, there is a dispatcher attached to this particular topology manager that attempts to register locally registered identities with remote synchronizers, by sending them to the synchronizer topology managers, who then decide on whether they want to include them or not.

The careful reader will have noted that the described identity system indeed does not have a single root of trust or decision maker on who is part of the overall system or not. But also that the topology state for the distributed synchronization varies from synchronizer to synchronizer, allowing very flexible topologies and setups.

Legal Identities¶

In Canton, we separate a system identity from the legal identity. While the above mechanism allows to establish a common, verified and authorized knowledge of system entities, it doesn’t guarantee that a certain unique identifier really corresponds to a particular legal identity. Even more so, while the unique identifier remains stable, a legal identity might change, for example in the case of a merger of two companies. Therefore, Canton provides an administrative command which allows one to associate a randomized system identity with a human readable display name using the participant.parties.set_display_name command.

Note

A party display name is private to the participant. If such names should be shared among participants, we recommend to build a corresponding Daml workflow and some automation logic, listening to the results of the Daml workflow and updating the display name accordingly.

Life of a Party¶

In the tutorials, we use the participant.parties.enable("name") function to setup a party on a participant. To understand the identity management system in Canton, it helps to look at the steps under the hood of how a new party is added:

The participant.parties.enable function determines the unique identifier of the participant: participant.id.
The party name is built as name::<namespace>, where the namespace is the one of the participant.
A new party-to-participant mapping is authorized on the Admin API: participant.topology.party_to_participant_mappings.authorize(...)
The ParticipantTopologyManager gets invoked by the GRPC request, creating a new SignedTopologyTransaction and tests whether the authorization can be added to the local topology state. If it can, the new topology transaction is added to the store.
The ParticipantTopologyDispatcher picks up the new transaction and requests the addition on all synchronizers via the RegisterTopologyTransactionRequest message sent to the topology manager through the sequencer.
A synchronizer receives this request and processes it according to the policy (open or permissioned). The default setting is open.
If approved, the request service attempts to add the new topology transaction to the SynchronizerTopologyManager.
The SynchronizerTopologyManager checks whether the new topology transaction can be added to the synchronizer topology state. If yes, it gets written to the local topology store.
The ParticipantTopologyDispatcher picks up the new transaction and sends it to all participants (and back to itself) through the sequencer.
The sequencer timestamps the transaction and embeds it into the transaction stream.
The participants receive the transaction, verify the integrity and correctness against the topology state and add it to the state with the timestamp of the sequencer, such that everyone has a synchronous topology state.

Note that the participant.parties.enable macro only works if the participant controls their namespace themselves, either directly by having the namespace key or through delegation (via NamespaceDelegation).

Participant Onboarding¶

Key to supporting topological flexibility is that participants can easily be added to new synchronizers. Therefore, the on-boarding of new participants to synchronizers needs to be secure but convenient. Looking at the console command, we note that in most examples, we are using the connect command to connect a participant to a synchronizer. The connect command just wraps a set of admin-api commands:

val certificates = OptionUtil.emptyStringAsNone(certificatesPath).map { path =>
  BinaryFileUtil.readByteStringFromFile(path) match {
    case Left(err) => throw new IllegalArgumentException(s"failed to load $path: $err")
    case Right(bs) => bs
  }
}
SynchronizerConnectionConfig.tryGrpcSingleConnection(
  synchronizerAlias,
  sequencerAlias,
  connection,
  manualConnect,
  physicalSynchronizerId,
  certificates,
  priority,
  initialRetryDelay,
  maxRetryDelay,
  timeTrackerConfig,
)

// connect to the new synchronizer
consoleEnvironment.run {
  ParticipantCommands.synchronizers.connect(runner, config, validation)
}

We note that from a user perspective, all that needs to happen by default is to provide the connection information and accept the terms of service (if required by the synchronizer) to set up a new synchronizer connection. There is no separate onboarding step performed, no giant certificate signing exercise happens, everything is set up during the first connection attempt. However, quite a few steps happen behind the scenes. Therefore, we briefly summarise the process here step by step:

The administrator of an existing participant needs to invoke the synchronizers.connect_local command to add a new synchronizer. The mandatory arguments are a synchronizer alias (used internally to refer to a particular connection) and the sequencer connection URL (HTTP or HTTPS) including an optional port http[s]://hostname[:port]/path. Optional are a certificates path for a custom TLS certificate chain (otherwise the default jre root certificates are used) and the synchronizer id of a synchronizer. The synchronizer id is the unique identifier of the synchronizer that can be defined to prevent man-in-the-middle attacks (very similar to an SSH key fingerprint).
The participant opens a GRPC channel to the SequencerConnectService.
The participant contacts the SequencerConnectService and checks if using the synchronizer requires signing specific terms of services. If required, the terms of service are displayed to the user and an approval is locally stored at the participant for later. If approved, the participant attempts to connect to the sequencer.
The participant verifies that the remote synchronizer is running a protocol version compatible with the participant’s version using the SequencerConnectService.handshake. If the participant runs an incompatible protocol version, the connection will fail.
The participant downloads and verifies the Synchronizer ID from the Synchronizer. The Synchronizer ID can be used to verify the correct authorization of the topology transactions of the synchronizer entities. If the synchronizer id has been provided previously during the synchronizers.connect_local call (or in a previous session), the two IDs are compared. If they are not equal, the connection fails. If the synchronizer id was not provided during the synchronizers.connect_local call, the participant uses and stores the one downloaded. We assume here that the synchronizer id is obtained by the participant through a secure channel such that it is sure to be talking to the right synchronizer. Therefore, this secure channel can be either something happening outside of Canton or can be provided by TLS during the first time we contact a synchronizer.
The participant downloads the static synchronizer parameters, which are the parameters used for the transaction protocol on the particular synchronizer, such as the cryptographic keys supported by this synchronizer.
The participant connects to the sequencer initially as an unauthenticated member. Such members can only send transactions to the synchronizer topology manager. The participant then sends an initial set of topology transactions required to identify the participant and define the keys used by the participant to the SynchronizerTopologyManagerRequestService. The request service inspects the validity of the transactions and decides based on the configured synchronizer on-boarding policy. The currently supported policies are open (default) and permissioned. While open is convenient for permissionless systems and for development, it will accept any new participant and any topology transaction. The permissioned policy will accept the participant’s onboarding transactions only if the participant has been added to the allow-list beforehand.
The request service forwards the transactions to the synchronizer topology manager, which attempts to add them to the state (and thus trigger the distribution to the other members on a synchronizer). The result of the onboarding request is sent to the unauthenticated member who disconnects upon receiving the response.
If the onboarding request is approved, the participant now attempts to connect to the sequencer as the actual participant.
Once the participant is properly enabled on the synchronizer and its signing key is known, the participant can subscribe to the SequencerService with its identity. To do that and to verify the authorization of any action on the SequencerService, the participant must obtain an authorization token from the synchronizer. For this purpose, the participant requests a Challenge from the synchronizer. The synchronizer will provide it with a nonce and the fingerprint of the key to be used for authentication. The participant signs this nonce (together with the synchronizer id) using the corresponding private key. The reason for the fingerprint is simple: the participant needs to sign the token using the participant’s signing key as defined by the synchronizer topology state. However, as the participant will learn the true synchronizer topology state only by reading from the SequencerService, it cannot know what the key is. Therefore, the synchronizer discloses this part of the synchronizer topology state as part of the authorization challenge.
Using the created authentication token, the participant starts to use the SequencerService. On the synchronizer side, the synchronizer verifies the authenticity and validity of the token by verifying that the token is the expected one and is signed by the participant’s signing key. The token is used to authenticate every GRPC invocation and needs to be renewed regularly.
The participant sets up the ParticipantTopologyDispatcher, which is the process that tries to push all topology transactions created at the participant node’s topology manager to the synchronizer topology manager. If the participant is using its topology manager to manage its identity on its own, these transactions contain all the information about the registered parties or supported packages.
As mentioned above, the first set of messages received by the participant through the sequencer contains the synchronizer topology state, which includes the signing keys of the synchronizer entities. These messages are signed by the sequencer and topology manager and are self-consistent. If the participants know the synchronizer id, they can verify that they are talking to the expected synchronizer and that the keys of the synchronizer entities have been authorized by the owner of the key governing the synchronizer id.
Once the initial topology transactions have been read, the participant is ready to process transactions and send commands.
When a participant is (re-)enabled, the synchronizer topology dispatcher analyses the set of topology transactions the participant has missed before. It sends these transactions to the participant via the sequencer, before publicly enabling the participant. Therefore, when the participant starts to read messages from the sequencer, the initially received messages will be the topology state of the synchronizer.

Default Initialization¶

The default initialization behavior of participant nodes and synchronizers is to run their own topology manager. This provides a convenient, automatic way to configure the nodes and make them usable without manual intervention, but it can be turned off by setting the auto-init = false configuration option before the first startup.

During the auto initialization, the following steps occur:

On the synchronizer, we generate four signing keys: one for the namespace and one each for the sequencer, mediator and topology manager. On the participant, we generate three keys: a namespace key, a signing key and an encryption key.
Using the fingerprint of the namespace, we generate the participant identity. For understandability, we use the node name used in the configuration file. This will change into a random identifier for privacy reasons. Once we’ve generated it, we set it using the set_id admin-api call.
We create a root certificate as NamespaceDelegation using the namespace key, signing with the namespace key.
Then, we create an OwnerToKeyMapping for the participant or synchronizer entities.

The init.identity object can be set to control the behavior of the auto initialization. For instance, it is possible to control the identifier name that will be given to the node during the initialization. There are 3 possible configurations:

Use the node name as the node identifier

canton.participants.participant1.init.identity = {
  type = auto
  identifier.type = config
}

Explicitly set a name

canton.participants.participant1.init.identity {
    type = auto
    identifier = {
        type = explicit
        name = MyName
    }
}

Generate a random name

canton.participants.participant1.init.identity {
    type = auto
    identifier.type = random
}

Identity Setup Guide¶

As explained, Canton nodes auto-initialize by default, running their own topology managers. This is convenient for development and prototyping. Actual deployments require more care and therefore, this section should serve as a brief guideline.

Canton topology managers have one crucial task they must not fail at: do not lose access to or control of the root of trust (namespace keys). Any other key problem can somehow be recovered by revoking an old key and issuing a new owner to key association. Therefore, it is advisable that participants and parties are associated with a namespace managed by a topology manager that has sufficient operational setups to guarantee the security and integrity of the namespace.

Therefore, a participant or synchronizer can

Run their own topology manager with their identity namespace key as part of the participant node.
Run their own topology manager on a detached computer in a self-built setup that exports topology transactions and transports them to the respective node (i.e. via burned CD roms).
Ask a trusted topology manager to issue a set of identifiers within the trusted topology manager’s namespace as delegations and import the delegations to the local participant topology manager.
Let a trusted topology manager manage all the topology state on-behalf.

Obviously, there are more combinations and options possible, but these options here describe some common options with different security and recoverability options.

To reduce the risk of losing namespace keys, additional keys can be created and allowed to operate on a certain namespace. In fact, we recommend doing this and avoiding storing the root key on a live node.

User Identity Management¶

So far we have covered how on-ledger identities are managed.

Every participant also needs to manage access to their local Ledger API and be able to give applications permission to read or write to that API on behalf of parties. While an on-ledger identity is represented as a party, an application on the Ledger API is represented and managed as a user. A Ledger API server manages applications’ identities through:

authentication: recognizing which user an application corresponds to (essentially by matching an application name with a user name)
authorization: knowing which rights an authenticated user has and restricting their Ledger API access according to those rights

Authentication is based on JWT and covered in the application development/authorization section of the manual; the related Ledger API authorization configuration is covered in the Ledger API JWT configuration section.

Authorization is managed by the Ledger API’s User Management Service. In essence, a user is a mapping from a user name to a set of parties with read or write permissions. In more detail a user consists of:

a user ID (also called user name)
an active/deactivated status (can be used to temporarily ban a user from accessing the Ledger API)
an optional primary party (indicates which party to use by default when submitting a Ledger API command request as this user)
a set of user rights (describes whether a user has access to the admin portion of the Ledger API and what parties this user can act or read as)
a set of custom annotations (string-based key-value pairs, stored locally on the Ledger API server, that can be used to attach extra information to this party, e.g. how it relates to some business entity)

All these properties except the user ID can be modified. To learn more about annotations refer to the Ledger API Reference documentation. For an overview of the Ledger API’s UserManagementService, see this section.

You can manage users through the Canton console user management commands, an alpha feature. See the cookbook below for some concrete examples of how to manage users.

Cookbook¶

Manage Users¶

In this section, we present how you can manage participant users using the Canton console commands. First, we create three parties that we’ll use in subsequent examples:

@ val Seq(alice, bob, eve) = Seq("alice", "bob", "eve").map(p => participant1.parties.enable(name = p))
    Seq(alice, bob, eve) : Seq[PartyId] = List(alice::12201ff69b1d..., bob::12201ff69b1d..., eve::12201ff69b1d...)

Create¶

Next, create a user called myuser with act-as alice and read-as bob permissions and active user status. This user’s primary party is alice. The user is not an administrator and has some custom annotations.

@ val user = participant1.ledger_api.users.create(id = "myuser", actAs = Set(alice), readAs = Set(bob), primaryParty = Some(alice), participantAdmin = false, isDeactivated = false, annotations = Map("foo" -> "bar", "description" -> "This is a description"))
    user : User = User(
      id = "myuser",
      primaryParty = Some(value = alice::12201ff69b1d...),
      isDeactivated = false,
      annotations = Map("foo" -> "bar", "description" -> "This is a description"),
      identityProviderId = ""
    )

There are some restrictions on what constitutes a valid annotation key. In contrast, the only constraint for annotation values is that they must not be empty. To learn more about annotations refer to the Ledger API Reference documentation.

Update¶

You can update a user’s primary party, active/deactivated status and annotations. (You can also change what rights a user has, but using a different method presented further below.)

In the following snippet, you change the user’s primary party to be unassigned, leave the active/deactivated status intact, and update the annotations. In the annotations, you change the value of the description key, remove the foo key and add the new baz key. The return value contains the updated state of the user:

@ val updatedUser = participant1.ledger_api.users.update(id = user.id, modifier = user => { user.copy(primaryParty = None, annotations = user.annotations.updated("description", "This is a new description").removed("foo").updated("baz", "bar")) })
    updatedUser : User = User(
      id = "myuser",
      primaryParty = None,
      isDeactivated = false,
      annotations = Map("description" -> "This is a new description", "baz" -> "bar"),
      identityProviderId = ""
    )

You can also update the user’s identity provider ID. In the following snippets, you change the user’s identity provider ID to the newly created one. Note that originally the user belonged to the default identity provider whose id is represented as the empty string `""`.

@ participant1.ledger_api.identity_provider_config.create("idp-id1", isDeactivated = false, jwksUrl = "http://someurl", issuer = "issuer1", audience = None)
    res4: com.digitalasset.canton.ledger.api.IdentityProviderConfig = IdentityProviderConfig(
      identityProviderId = Id(value = "idp-id1"),
      isDeactivated = false,
      jwksUrl = JwksUrl(value = "http://someurl"),
      issuer = "issuer1",
      audience = None
    )

@ participant1.ledger_api.users.update_idp("myuser", sourceIdentityProviderId="", targetIdentityProviderId="idp-id1")

@ participant1.ledger_api.users.get("myuser", identityProviderId="idp-id1")
    res6: User = User(
      id = "myuser",
      primaryParty = None,
      isDeactivated = false,
      annotations = Map("description" -> "This is a new description", "baz" -> "bar"),
      identityProviderId = "idp-id1"
    )

You can change the user’s identity provider ID back to the default one:

@ participant1.ledger_api.users.update_idp("myuser", sourceIdentityProviderId="idp-id1", targetIdentityProviderId="")

@ participant1.ledger_api.users.get("myuser", identityProviderId="")
    res8: User = User(
      id = "myuser",
      primaryParty = None,
      isDeactivated = false,
      annotations = Map("description" -> "This is a new description", "baz" -> "bar"),
      identityProviderId = ""
    )

Inspect¶

You can fetch the current state of the user as follows:

@ participant1.ledger_api.users.get(user.id)
    res9: User = User(
      id = "myuser",
      primaryParty = None,
      isDeactivated = false,
      annotations = Map("description" -> "This is a new description", "baz" -> "bar"),
      identityProviderId = ""
    )

You can query what rights a user has:

@ participant1.ledger_api.users.rights.list(user.id)
    res10: UserRights = UserRights(
      actAs = Set(alice::12201ff69b1d...),
      readAs = Set(bob::12201ff69b1d...),
      executeAs = Set(),
      readAsAnyParty = false,
      executeAsAnyParty = false,
      participantAdmin = false,
      identityProviderAdmin = false
    )

You can grant more rights. The returned value contains only newly granted rights; it does not contain rights the user already had even if you attempted to grant them again (like the read-as alice right in this example):

@ participant1.ledger_api.users.rights.grant(id = user.id, actAs = Set(alice, bob), readAs = Set(eve), participantAdmin = true)
    res11: UserRights = UserRights(
      actAs = Set(alice::12201ff69b1d..., bob::12201ff69b1d...),
      readAs = Set(eve::12201ff69b1d..., bob::12201ff69b1d...),
      executeAs = Set(),
      readAsAnyParty = false,
      executeAsAnyParty = false,
      participantAdmin = true,
      identityProviderAdmin = false
    )

You can revoke rights from the user. Again, the returned value contains only rights that were actually removed:

@ participant1.ledger_api.users.rights.revoke(id = user.id, actAs = Set(bob), readAs = Set(alice), participantAdmin = true)
    res12: UserRights = UserRights(
      actAs = Set(alice::12201ff69b1d...),
      readAs = Set(bob::12201ff69b1d..., eve::12201ff69b1d...),
      executeAs = Set(),
      readAsAnyParty = false,
      executeAsAnyParty = false,
      participantAdmin = false,
      identityProviderAdmin = false
    )

Now that you have granted and revoked some rights, you can fetch all of the user’s rights again and see what they are:

@ participant1.ledger_api.users.rights.list(user.id)
    res13: UserRights = UserRights(
      actAs = Set(alice::12201ff69b1d...),
      readAs = Set(bob::12201ff69b1d..., eve::12201ff69b1d...),
      executeAs = Set(),
      readAsAnyParty = false,
      executeAsAnyParty = false,
      participantAdmin = false,
      identityProviderAdmin = false
    )

Also, multiple users can be fetched at the same time. To do that, first create another user called myotheruser and then list all the users whose user name starts with my:

@ participant1.ledger_api.users.create(id = "myotheruser")
    res14: User = User(
      id = "myotheruser",
      primaryParty = None,
      isDeactivated = false,
      annotations = Map(),
      identityProviderId = ""
    )

@ participant1.ledger_api.users.list(filterUser = "my")
    res15: UsersPage = UsersPage(
      users = Vector(
        User(
          id = "myotheruser",
          primaryParty = None,
          isDeactivated = false,
          annotations = Map(),
          identityProviderId = ""
        ),
        User(
          id = "myuser",
          primaryParty = None,
          isDeactivated = false,
          annotations = Map("description" -> "This is a new description", "baz" -> "bar"),
          identityProviderId = ""
        )
      ),
      nextPageToken = ""
    )

Decommission¶

You can delete a user by its ID:

@ participant1.ledger_api.users.delete("myotheruser")

You can confirm it has been removed by e.g. listing it:

@ participant1.ledger_api.users.list("myotheruser")
    res17: UsersPage = UsersPage(users = Vector(), nextPageToken = "")

If you want to prevent a user from accessing the Ledger API it may be better to deactivate it rather than deleting it. A deleted user can be recreated as if it never existed in the first place, while a deactivated user must be explicitly reactivated to be able to access the Ledger API again.

@ participant1.ledger_api.users.update("myuser", user => user.copy(isDeactivated = true))
    res18: User = User(
      id = "myuser",
      primaryParty = None,
      isDeactivated = true,
      annotations = Map("description" -> "This is a new description", "baz" -> "bar"),
      identityProviderId = ""
    )

Configure a default Participant Admin¶

Fresh participant nodes come with a default participant admin user called participant_admin, which can be used to bootstrap other users. You might prefer to have an admin user with a different user ID ready on a participant startup. For such situations, you can specify an additional participant admin user with the user ID of your choice.

Note

If a user with the specified ID already exists, then no additional user will be created, even if the preexisting user was not an admin user.

additional-admin.conf¶

canton.participants.myparticipant.ledger-api.user-management-service.additional-admin-user-id = "my-admin-id"

Adding a new Party to a Participant¶

The simplest operation is adding a new party to a participant. For this, we add it normally at the topology manager of the participant, which in the default case is part of the participant node. There is a simple macro to enable the party on a given participant if the participant is running their own topology manager:

val name = "Gottlieb"
val partyId = participant1.parties.enable(name)

This will create a new party in the namespace of the participant’s topology manager.

And there is the corresponding disable macro:

participant1.parties.disable(partyId)

The macros themselves just use topology.party_to_participant_mappings.authorize to create the new party, but add some convenience such as automatically determining the parameters for the authorize call.

Note

Please note that the participant.parties.enable macro will add the parties to the same namespace as the participant is in. It only works if the participant has authority over that namespace either by possessing the root or a delegated key.

Client Controlled Party¶

Parties are only weakly tied to participant nodes. They can be allocated in their own namespace and then delegated to a given participant. For simplicity and convenience, the participant creates new parties in its own namespace by default, but there are situations where this is not desired.

A common scenario is that you first host the party on behalf of your client, but subsequently hand over the party to the client’s node. With the default party allocation, you would still control the party of the client.

To avoid this, you need your client to create a new party on their own and export a party delegation to you. This party delegation can then be imported into your topology state, which will then allow you to act on behalf of the party.

For this process, we use a participant node which won’t be connected to any synchronizer. We don’t need the full node, but just the topology manager. First, we need to find out the participant ID of the hosting node:

@ hosting.id.toProtoPrimitive
    res1: String = "PAR::participant2::1220a4d7463bd34b2ba3704401b48ab41d8f88cdcbe512fc1ef071aad97fef106161"

This identifier needs to be communicated to the client and can be imported using ParticipantId.tryFromProtoPrimitive. The client then creates first a new key (they could use the default key created):

@ val secret = client.keys.secret.generate_signing_key("my-party-key", SigningKeyUsage.NamespaceOnly)
    secret : SigningPublicKey = SigningPublicKey(
      id = 1220b6963614...,
      format = DER-encoded X.509 SubjectPublicKeyInfo,
      keySpec = EC-Curve25519,
      usage = namespace
    )

and an appropriate root certificate for this key:

@ val rootCert = client.topology.namespace_delegations.propose_delegation(Namespace(secret.fingerprint), secret, CanSignAllMappings)
    rootCert : SignedTopologyTransaction[TopologyChangeOp, NamespaceDelegation] = SignedTopologyTransaction(
      TopologyTransaction(
        NamespaceDelegation(
          1220b6963614...,
          SigningPublicKey(
            id = 1220b6963614...,
            format = DER-encoded X.509 SubjectPublicKeyInfo,
            keySpec = EC-Curve25519,
            usage = namespace
          ),
          CanSignAllMappings
        ),
        serial = 1,
        operation = Replace,
        hash = SHA-256:d46951e7ffdf...
      ),
      signatures = 1220b6963614...
    )

This root certificate needs to be exported into a file:

@ import com.digitalasset.canton.util.BinaryFileUtil

@ rootCert.writeToFile("rootCert.bin")

Define the party ID of the party you want to create:

@ val partyId = PartyId.tryCreate("Client", secret.fingerprint)
    partyId : PartyId = Client::1220b6963614...

Create and export the party to participant delegation:

@ val partyDelegation = client.topology.party_to_participant_mappings.propose(partyId, Seq((hostingNodeId, ParticipantPermission.Submission)))
    partyDelegation : SignedTopologyTransaction[TopologyChangeOp, PartyToParticipant] = SignedTopologyTransaction(
      TopologyTransaction(
        PartyToParticipant(
          Client::1220b6963614...,
          PositiveNumeric(1),
          Vector(HostingParticipant(PAR::participant2::1220a4d7463b..., Submission, false)),
          None
        ),
        serial = 1,
        operation = Replace,
        hash = SHA-256:6c01b8007160...
      ),
      signatures = 1220b6963614...,
      proposal
    )

@ partyDelegation.writeToFile("partyDelegation.bin")

The client now shares the rootCert.bin and partyDelegation.bin files with the hosting node. The hosting node imports them into their topology state:

@ hosting.topology.transactions.load_single_from_files(
    files = Seq("rootCert.bin", "partyDelegation.bin"),
    store = synchronizerId,
)

Finally, the hosting node needs to issue the corresponding topology transaction to enable the party on its node:

@ hosting.topology.party_to_participant_mappings.propose(partyId, Seq((hosting.id, ParticipantPermission.Submission)))
    res10: SignedTopologyTransaction[TopologyChangeOp, PartyToParticipant] = SignedTopologyTransaction(
      TopologyTransaction(
        PartyToParticipant(
          Client::1220b6963614...,
          PositiveNumeric(1),
          Vector(HostingParticipant(PAR::participant2::1220a4d7463b..., Submission, false)),
          None
        ),
        serial = 1,
        operation = Replace,
        hash = SHA-256:6c01b8007160...
      ),
      signatures = 1220a4d7463b...,
      proposal
    )

Party on Multiple Nodes¶

Hosting a party across multiple participants increases its liveness and fault tolerance, as any hosting participant can act on the party’s behalf based on their permissions. While all hosting participants share the same view of the party’s contracts, they are also all included in its transactions. This creates overhead, limiting the feature’s scalability. For sharing data with many participants, explicit disclosure is a more suitable approach.

Manually Initializing a Node¶

There are situations where a node should not be automatically initialized, but where you should control each step of the initialization. For example, this might be the case when a node in the setup does not control its own identity, when you do not want to store the identity key on the node for security reasons, or when you want to set our own keys (e.g. when keys are externally stored in a Key Management Service - KMS).

The following demonstrates the basic steps on how to initialize a node:

Keys Initialization¶

The following steps describe how to manually generate the necessary Canton keys (e.g. for a participant):

// Create a signing key used to define the node identity.
val namespaceKey =
  node.keys.secret
    .generate_signing_key(
      name = node.name + s"-${SigningKeyUsage.Namespace.identifier}",
      SigningKeyUsage.NamespaceOnly,
    )

// Create a signing key used to authenticate the node toward the Sequencer.
val sequencerAuthKey =
  node.keys.secret.generate_signing_key(
    name = node.name + s"-${SigningKeyUsage.SequencerAuthentication.identifier}",
    SigningKeyUsage.SequencerAuthenticationOnly,
  )

// Create a signing key used to sign protocol messages.
val signingKey =
  node.keys.secret
    .generate_signing_key(
      name = node.name + s"-${SigningKeyUsage.Protocol.identifier}",
      SigningKeyUsage.ProtocolOnly,
    )

// Create the encryption key.
val encryptionKey =
  node.keys.secret.generate_encryption_key(name = node.name + "-encryption")

Note

Be aware that in some particular use cases, you might want to register keys rather than generate new ones (for instance when you have pre-generated KMS keys that you want to use). Please refer to External Key Storage with a Key Management Service (KMS) for more details.

Synchronizer Initialization¶

The following steps describe how to manually initialize a synchronizer node:

Participant Initialization¶

The following steps describe how to manually initialize a participant node:

Identity Management¶

Introduction¶

What is a Canton Identity?¶

Unique Identifier¶

Topology Transactions¶

Legal Identities¶

Life of a Party¶

Participant Onboarding¶

Default Initialization¶

Identity Setup Guide¶

User Identity Management¶

Cookbook¶

Manage Users¶

Create¶

Update¶

Inspect¶

Decommission¶

Configure a default Participant Admin¶

Adding a new Party to a Participant¶

Client Controlled Party¶

Party on Multiple Nodes¶

Manually Initializing a Node¶

Keys Initialization¶

Synchronizer Initialization¶

Participant Initialization¶

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