From 3a69f2a60c2051d0c481372bbe90e7f001afbb88 Mon Sep 17 00:00:00 2001 From: Joel Dudley Date: Mon, 23 Oct 2017 10:24:36 +0100 Subject: [PATCH] Adds receiver side of sync flow to ID docs. Cleanup. --- docs/source/api-identity.rst | 159 ++++++++++-------- .../corda/finance/flows/TwoPartyTradeFlow.kt | 2 + 2 files changed, 90 insertions(+), 71 deletions(-) diff --git a/docs/source/api-identity.rst b/docs/source/api-identity.rst index c87b50a45f..3ab041d6b2 100644 --- a/docs/source/api-identity.rst +++ b/docs/source/api-identity.rst @@ -7,61 +7,59 @@ API: Identity Party ----- -Identities on the network are represented by ``AbstractParty``. There are two types of ``AbstractParty``: +Parties on the network are represented using the ``AbstractParty`` class. There are two types of ``AbstractParty``: * ``Party``, identified by a ``PublicKey`` and a ``CordaX500Name`` +* ``AnonymousParty``, identified by a ``PublicKey`` only -* ``AnonymousParty``, identified by a ``PublicKey`` +Using ``AnonymousParty`` to identify parties in states and commands prevents nodes from learning the identities +of the parties involved in a transaction when they verify the transaction's dependency chain. When preserving the +anonymity of each party is not required (e.g. for internal processing), ``Party`` can be used instead. -For example, in a transaction sent to your node as part of a chain of custody it is important you can convince yourself -of the transaction's validity, but equally important that you don't learn anything about who was involved in that -transaction. In these cases ``AnonymousParty`` should be used by flows constructing when transaction states and commands. -In contrast, for internal processing where extended details of a party are required, the ``Party`` class should be used -instead. The identity service provides functionality for flows to resolve anonymous parties to full parties, dependent -on the anonymous party's identity having been registered with the node earlier (typically this is handled by -``SwapIdentitiesFlow`` or ``IdentitySyncFlow``, discussed below). +The identity service allows flows to resolve ``AnonymousParty`` to ``Party``, but only if the anonymous party's +identity has already been registered with the node (typically handled by ``SwapIdentitiesFlow`` or +``IdentitySyncFlow``, discussed below). -Party names are held within the ``CordaX500Name`` data class, which enforces the structure of names within Corda, as -well as ensuring a consistent rendering of the names in plain text. +Party names use the ``CordaX500Name`` data class, which enforces the structure of names within Corda, as well as +ensuring a consistent rendering of the names in plain text. -The support for both Party and AnonymousParty classes in Corda enables sophisticated selective disclosure of identity -information. For example, it is possible to construct a Transaction using an AnonymousParty, so nobody can learn of your -involvement by inspection of the transaction, yet prove to specific counterparts that this AnonymousParty actually is -owned by your well known identity. This disclosure is achieved through the use of the PartyAndCertificate data class -which can be propagated to those who need to know, and contains the Party's X.509 certificate path to provide proof of -ownership by a well known identity. +Support for both ``Party`` and ``AnonymousParty`` classes in Corda enables sophisticated selective disclosure of +identity information. For example, it is possible to construct a transaction using an ``AnonymousParty`` (so nobody can +learn of your involvement by inspection of the transaction), yet prove to specific counterparts that this +``AnonymousParty`` actually corresponds to your well-known identity. This is achieved using the +``PartyAndCertificate`` data class, which contains the X.509 certificate path proving that a given ``AnonymousParty`` +corresponds to a given ``Party``. Each ``PartyAndCertificate`` can be propagated to counterparties on a need-to-know +basis. -The PartyAndCertificate class is also used in the network map service to represent well known identities, in which -scenario the certificate path proves its issuance by the Doorman service. +The ``PartyAndCertificate`` class is also used by the network map service to represent well-known identities, with the +certificate path proving the certificate was issued by the doorman service. - -Confidential Identities +Confidential identities ----------------------- - -Confidential identities are key pairs where the corresponding X.509 certificate (and path) are not made public, so that parties who -are not involved in the transaction cannot identify its participants. They are owned by a well known identity, which -must sign the X.509 certificate. Before constructing a new transaction the involved parties must generate and send new -confidential identities to each other, a process which is managed using ``SwapIdentitiesFlow`` (discussed below). The -public keys of these confidential identities are then used when generating output states and commands for the transaction. +Confidential identities are key pairs where the corresponding X.509 certificate (and path) are not made public, so that +parties who are not involved in the transaction cannot identify the owner. They are owned by a well-known identity, +which must sign the X.509 certificate. Before constructing a new transaction the involved parties must generate and +exchange new confidential identities, a process which is managed using ``SwapIdentitiesFlow`` (discussed below). The +public keys of these confidential identities are then used when generating output states and commands for the +transaction. Where using outputs from a previous transaction in a new transaction, counterparties may need to know who the involved -parties are. One example is in ``TwoPartyTradeFlow`` which delegates to ``CollectSignaturesFlow`` to gather certificates -from both parties. ``CollectSignaturesFlow`` requires that a confidential identity of the initiating node has signed -the transaction, and verifying this requires the receiving node has a copy of the confidential identity for the input -state. ``IdentitySyncFlow`` can be used to synchronize the confidential identities we have the certificate paths for, in -a single transaction, to another node. +parties are. One example is the ``TwoPartyTradeFlow``, where an existing asset is exchanged for cash. If confidential +identities are being used, the buyer will want to ensure that the asset being transferred is owned by the seller, and +the seller will likewise want to ensure that the cash being transferred is owned by the buyer. Verifying this requires +both nodes to have a copy of the confidential identities for the asset and cash input states. ``IdentitySyncFlow`` +manages this process. It takes as inputs a transaction and a counterparty, and for every confidential identity involved +in that transaction for which the calling node holds the certificate path, it sends this certificate path to the +counterparty. -.. note:: ``CollectSignaturesFlow`` requires that the initiating node has signed the transaction, and as such all nodes - providing signatures must recognise the signing key used by the initiating node as being either its well known identity - or a confidential identity they have the certificate for. +SwapIdentitiesFlow +~~~~~~~~~~~~~~~~~~ +``SwapIdentitiesFlow`` is typically run as a subflow of another flow. It takes as its sole constructor argument the +counterparty we want to exchange confidential identities with. It returns a mapping from the identities of the caller +and the counterparty to their new confidential identities. In the future, this flow will be extended to handle swapping +identities with multiple parties at once. -Swap identities flow -~~~~~~~~~~~~~~~~~~~~ - -``SwapIdentitiesFlow`` takes the party to swap identities with in its constructor (the counterparty), and is typically run as a subflow of -another flow. It returns a mapping from well known identities of the calling flow and our counterparty to the new -confidential identities; in future this will be extended to handle swapping identities with multiple parties. -You can see an example of it being used in ``TwoPartyDealFlow.kt``: +You can see an example of using ``SwapIdentitiesFlow`` in ``TwoPartyDealFlow.kt``: .. container:: codeset @@ -71,29 +69,35 @@ You can see an example of it being used in ``TwoPartyDealFlow.kt``: :end-before: DOCEND 2 :dedent: 8 -The swap identities flow goes through the following key steps: +``SwapIdentitiesFlow`` goes through the following key steps: -1. Generate a nonce value to form a challenge to the other nodes. -2. Send nonce value to all counterparties, and receive their nonce values. -3. Generate a new confidential identity from our well known identity. +1. Generate a nonce value to form a challenge to the other nodes +2. Send nonce value to all counterparties, and receive their nonce values +3. Generate a new confidential identity from our well-known identity 4. Create a data blob containing the new confidential identity (public key, name and X.509 certificate path), - and the hash of the nonce values. -5. Sign the resulting data blob with the confidential identity's private key. -6. Send the confidential identity and data blob signature to all counterparties, while receiving theirs. -7. Verify the signatures to ensure that identities were generated by the involved set of parties. -8. Verify the confidential identities are owned by the expected well known identities. -9. Store the confidential identities and return them to the calling flow. + and the hash of the nonce values +5. Sign the resulting data blob with the confidential identity's private key +6. Send the confidential identity and data blob signature to all counterparties, while receiving theirs +7. Verify the signatures to ensure that identities were generated by the involved set of parties +8. Verify the confidential identities are owned by the expected well known identities +9. Store the confidential identities and return them to the calling flow -This ensures not only that the confidential identity X.509 certificates are signed by the correct well known identities, -but also that the confidential identity private key is held by the counterparty, and that a party cannot claim ownership -another party's confidential identities belong to its well known identity. +This ensures not only that the confidential identity X.509 certificates are signed by the correct well-known +identities, but also that the confidential identity private key is held by the counterparty, and that a party cannot +claim ownership of another party's confidential identities. -Identity synchronization flow -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +IdentitySyncFlow +~~~~~~~~~~~~~~~~ +When constructing a transaction whose input states reference confidential identities, it is common for counterparties +to require knowledge of which well-known identity each confidential identity maps to. ``IdentitySyncFlow`` handles this +process. You can see an example of its use in ``TwoPartyTradeFlow.kt``. -When constructing a transaction whose input states reference confidential identities, it is common for other signing -entities (counterparties) to require to know which well known identities those confidential identities map to. The -``IdentitySyncFlow`` handles this process, and you can see an example of its use in ``TwoPartyTradeFlow.kt``: +``IdentitySyncFlow`` is divided into two parts: + +* ``IdentitySyncFlow.Send`` +* ``IdentitySyncFlow.Receive`` + +``IdentitySyncFlow.Send`` is invoked by the party initiating the identity synchronization: .. container:: codeset @@ -105,20 +109,33 @@ entities (counterparties) to require to know which well known identities those c The identity synchronization flow goes through the following key steps: -1. Extract participant identities from all input and output states and remove any well known identities. Required signers - on commands are currently ignored as they are presumed to be included in the participants on states, or to be well - known identities of services (such as an oracle service). +1. Extract participant identities from all input and output states and remove any well known identities. Required + signers on commands are currently ignored as they are presumed to be included in the participants on states, or to + be well-known identities of services (such as an oracle service) 2. For each counterparty node, send a list of the public keys of the confidential identities, and receive back a list - of those the counterparty needs the certificate path for. -3. Verify the requested list of identities contains only confidential identities in the offered list, and abort otherwise. -4. Send the requested confidential identities as ``PartyAndCertificate`` instances to the counterparty. + of those the counterparty needs the certificate path for +3. Verify the requested list of identities contains only confidential identities in the offered list, and abort + otherwise +4. Send the requested confidential identities as ``PartyAndCertificate`` instances to the counterparty .. note:: ``IdentitySyncFlow`` works on a push basis. The initiating node can only send confidential identities it has the X.509 certificates for, and the remote nodes can only request confidential identities being offered (are referenced in the transaction passed to the initiating flow). There is no standard flow for nodes to collect - confidential identities before assembling a transaction, and this is left for individual flows to manage if required. + confidential identities before assembling a transaction, and this is left for individual flows to manage if + required. -``IdentitySyncFlow`` will serve all confidential identities in the provided transaction, irrespective of well known +Meanwhile, ``IdentitySyncFlow.Receive`` is invoked by all the other (non-initiating) parties involved in the identity +synchronization process: + +.. container:: codeset + + .. literalinclude:: ../../finance/src/main/kotlin/net/corda/finance/flows/TwoPartyTradeFlow.kt + :language: kotlin + :start-after: DOCSTART 07 + :end-before: DOCEND 07 + :dedent: 12 + +``IdentitySyncFlow`` will serve all confidential identities in the provided transaction, irrespective of well-known identity. This is important for more complex transaction cases with 3+ parties, for example: * Alice is building the transaction, and provides some input state *x* owned by a confidential identity of Alice @@ -126,6 +143,6 @@ identity. This is important for more complex transaction cases with 3+ parties, * Charlie provides some input state *z* owned by a confidential identity of Charlie Alice may know all of the confidential identities ahead of time, but Bob not know about Charlie's and vice-versa. -The assembled transaction therefore has three input states *x*, *y* and *z*, for which only Alice possesses certificates -for all confidential identities. ``IdentitySyncFlow`` must send not just Alice's confidential identity but also any other -identities in the transaction to the Bob and Charlie. \ No newline at end of file +The assembled transaction therefore has three input states *x*, *y* and *z*, for which only Alice possesses +certificates for all confidential identities. ``IdentitySyncFlow`` must send not just Alice's confidential identity but +also any other identities in the transaction to the Bob and Charlie. \ No newline at end of file diff --git a/finance/src/main/kotlin/net/corda/finance/flows/TwoPartyTradeFlow.kt b/finance/src/main/kotlin/net/corda/finance/flows/TwoPartyTradeFlow.kt index 7fbbbc3cfc..a5f257771c 100644 --- a/finance/src/main/kotlin/net/corda/finance/flows/TwoPartyTradeFlow.kt +++ b/finance/src/main/kotlin/net/corda/finance/flows/TwoPartyTradeFlow.kt @@ -87,9 +87,11 @@ object TwoPartyTradeFlow { // Verify and sign the transaction. progressTracker.currentStep = VERIFYING_AND_SIGNING + // DOCSTART 07 // Sync identities to ensure we know all of the identities involved in the transaction we're about to // be asked to sign subFlow(IdentitySyncFlow.Receive(otherSideSession)) + // DOCEND 07 // DOCSTART 5 val signTransactionFlow = object : SignTransactionFlow(otherSideSession, VERIFYING_AND_SIGNING.childProgressTracker()) {