corda/docs/source/release-notes.rst

Release notes

Unreleased

Significant Changes in 4.0

• Retirement of non-elliptic Diffie-Hellman for TLS The TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 family of ciphers is retired from the list of allowed ciphers for TLS as it is a legacy cipher family not supported by all native SSL/TLS implementations.

• Reference states:

  Introduced the concept of "reference input states". A reference input state is a ContractState which can be referred to in a transaction by the contracts of input and output states but whose contract is not executed as part of the transaction verification process and is not consumed when the transaction is committed to the ledger but is checked for "current-ness". In other words, the contract logic isn't run for the referencing transaction only. It's still a normal state when it occurs in an input or output position.

Issues Fixed

• Cordform Gradle task (deployNodes) doesn't work when configFile element was used.

Release 3.2

As we see more Corda deployments in production this minor release of the open source platform brings several fixes that make it easier for a node to join Corda networks broader than those used when operating as part of an internal testing deployment. This will ensure Corda nodes will be free to interact with upcoming network offerings from R3 and others who may make broad-access Corda networks available.

• The Corda Network Builder

To make it easier to create more dynamic, flexible, networks for testing and deployment, with the 3.2 release of Corda we are shipping a graphical network bootsrapping tool (see network-builder) to facilitate the simple creation of more dynamic ad hoc dev-mode environments.

Using a graphical interface you can dynamically create and alter Corda test networks, adding nodes and CorDapps with the click of a button! Additionally, you can leverage its integration with Azure cloud services for remote hosting of Nodes and Docker instances for local testing.

• Split Compatibility Zone

Prior to this release compatibility zone membership was denoted with a single configuration setting

compatibilityZoneURL : "http://<host>(:<port>)"

That would indicate both the location of the Doorman service the node should use for registration of its identity as well as the Network Map service where it would publish its signed Node Info and retrieve the Network Map.

Compatibility Zones can now, however, be configured with the two disparate services, Doorman and Network Map, running on different URLs. If the compatibility zone your node is connecting to is configured in this manner, the new configuration looks as follows.

networkServices {
    doormanURL: "http://<host>(:<port>)"
    networkMapURL: "http://<host>(:<port>)"
}

Note

The compatibilityZoneURL setting should be considered deprecated in favour of the new networkServices settings group.

• The Blob Inspector

The blob inspector brings the ability to unpack serialized Corda blobs at the command line, giving a human readable interpretation of the encoded date.

Note

This tool has been shipped as a separate Jar previously. We are now including it as part of an official release.

Documentation on its use can be found here blob-inspector

• The Event Horizon

One part of joining a node to a Corda network is agreeing to the rules that govern that network as set out by the network operator. A node's membership of a network is communicated to other nodes through the network map, the service to which the node will have published its Node Info, and through which it receives the set of NodeInfos currently present on the network. Membership of that list is a finite thing determined by the network operator.

Periodically a node will republish its NodeInfo to the Network Map service. The Network Map uses this as a heartbeat to determine the status of nodes registered with it. Those that don't "beep" within the determined interval are removed from the list of registered nodes. The Event Horizon network parameter sets the upper limit within which a node must respond or be considered inactive.

Important

This does not mean a node is unregistered from the Doorman, only that its NodeInfo is removed from the Network Map. Should the node come back online it will be re-added to the published set of NodeInfos

Issues Fixed

• Update Jolokia to a more secure version [CORDA-1744]
• Add the Blob Inspector [CORDA-1709]
• Add support for the Event Horizon Network Parameter [CORDA-866]
• Add the Network Bootstrapper [CORDA-1717]
• Fixes for the finance CordApp[CORDA-1711]
• Allow Doorman and NetworkMap to be configured independently [CORDA-1510]
• Serialization fix for generics when evolving a class [CORDA-1530]
• Correct typo in an internal database table name [CORDA-1499] and [CORDA-1804]
• Hibernate session not flushed before handing over raw JDBC session to user code [CORDA-1548]
• Fix Postgres db bloat issue [CORDA-1812]
• Roll back flow transaction on exception [CORDA-1790]

Release 3.1

This rapid follow-up to Corda 3.0 corrects an issue discovered by some users of Spring Boot and a number of other smaller issues discovered post release. All users are recommended to upgrade.

Special Thanks

Without passionate and engaged users Corda would be all the poorer. As such, we are extremely grateful to Bret Lichtenwald for helping nail down a reproducible test case for the Spring Boot issue.

Major Bug Fixes

• Corda Serialization fails with "Unknown constant pool tag"

  This issue is most often seen when running a CorDapp with a Rest API using / provided by Spring Boot.

  The fundamental cause was Corda 3.0 shipping with an out of date dependency for the fast-classpath-scanner library, where the manifesting bug was already fixed in a released version newer than our dependant one. In response, we've updated our dependent version to one including that bug fix.

• Corda Versioning

  Those eagle eyed amongst you will have noticed for the 3.0 release we altered the versioning scheme from that used by previous Corda releases (1.0.0, 2.0.0, etc) with the addition of an prepended product name, resulting in corda-3.0. The reason for this was so that developers could clearly distinguish between the base open source platform and any distributions based on on Corda that may be shipped in the future (including from R3), However, we have heard the complaints and feel the pain that's caused by various tools not coping well with this change. As such, from now on the versioning scheme will be inverted, with this release being 3.1-corda.

  As to those curious as to why we dropped the patch number from the version string, the reason is very simple: there won't be any patches applied to a release of Corda. Either a release will be a collection of bug fixes and non API breaking changes, thus eliciting a minor version bump as with this release, or major functional changes or API additions and warrant a major version bump. Thus, rather than leave a dangling .0 patch version on every release we've just dropped it. In the case where a major security flaw needed addressing, for example, then that would generate a release of a new minor version.

Issues Fixed

• RPC server leaks if a single client submits a lot of requests over time [CORDA-1295]
• Flaky startup, no db transaction in context, when using postgresql [CORDA-1276]
• Corda's JPA classes should not be final or have final methods [CORDA-1267]
• Backport api-scanner changes [CORDA-1178]
• Misleading error message shown when node is restarted after the flag day
• Hash constraints not working from Corda 3.0 onwards
• Serialisation Error between Corda 3 RC01 and Corda 3
• Nodes don't start when network-map/doorman is down

Release 3.0

Corda 3.0 is here and brings with it a commitment to a wire stable platform, a path for contract and node upgradability, and a host of other exciting features. The aim of which is to enhance the developer and user experience whilst providing for the long term usability of deployed Corda instances. This release will provide functionality to ensure anyone wishing to move to the anticipated release of R3 Corda can do so seamlessly and with the assurance that stateful data persisted to the vault will remain understandable between newer and older nodes.

Special Thanks

As ever, we are grateful to the enthusiastic user and developer community that has grown up to surround Corda. As an open project we are always grateful to take code contributions from individual users where they feel they can add functionality useful to themselves and the wider community.

As such we'd like to extend special thanks to

• Ben Wyeth for providing a mechanism for registering a callback on app shutdown

  Ben's contribution can be found on GitHub here

• Tomas Tauber for adding support for running Corda atop PostgresSQL in place of the in-memory H2 service

  Tomas's contribution can be found on GitHub here

  Warning

  This is an experimental feature that has not been tested as part of our standard release testing.

• Rose Molina Atienza for correcting our careless spelling slip

  Rose's change can be found on GitHub here

Significant Changes in 3.0

• Wire Stability:

  Wire stability brings the same promise to developers for their data that API stability did for their code. From this point any state generated by a Corda system will always be retrievable, understandable, and seen as valid by any subsequently released version (versions 3.0 and above).

  Systems can thus be deployed safe in the knowledge that valuable and important information will always be accessible through upgrade and change. Practically speaking this means from this point forward upgrading all, or part, of a Corda network will not require the replaying of data; "it will just work".

  This has been facilitated by the switch over from Kryo to Corda's own AMQP based serialization framework, a framework designed to interoperate with stateful information and allow the evolution of such contract states over time as developers refine and improve their systems written atop the core Corda platform.

  • AMQP Serialization

    AMQP Serialization is now enabled for both peer to peer communication and the writing of states to the vault. This change brings a serialisation format that will allow us to deliver enhanced security and wire stability. This was a key prerequisite to enabling different Corda node versions to coexist on the same network and to enable easier upgrades.

    Details on the AMQP serialization framework can be found here <amqp_ref>. This provides an introduction and overview of the framework whilst more specific details on object evolution as it relates to serialization can be found in serialization-default-evolution and serialization-enum-evolution respectively.

    Note

    This release delivers the bulk of our transition from Kryo serialisation to AMQP serialisation. This means that many of the restrictions that were documented in previous versions of Corda are now enforced.

    In particular, you are advised to review the section titled Custom Types <amqp_custom_types_ref>. To aid with the transition, we have included support in this release for default construction and instantiation of objects with inaccessible private fields, but it is not guaranteed that this support will continue into future versions; the restrictions documented at the link above are the canonical source.

    Whilst this is an important step for Corda, in no way is this the end of the serialisation story. We have many new features and tools planned for future releases, but feel it is more important to deliver the guarantees discussed above as early as possible to allow the community to develop with greater confidence.

  Important

  Whilst Corda has stabilised its wire protocol and infrastructure for peer to peer communication and persistent storage of states, the RPC framework will, for this release, not be covered by this guarantee. The moving of the client and server contexts away from Kryo to our stable AMQP implementation is planned for the next release of Corda

  • Artemis and Bridges

    Corda has now achieved the long stated goal of using the AMQP 1.0 open protocol standard as its communication protocol between peers. This forms a strong and flexible framework upon which we can deliver future enhancements that will allow for much smoother integrations between Corda and third party brokers, languages, and messaging systems. In addition, this is also an important step towards formally defining the official peer to peer messaging protocol of Corda, something required for more in-depth security audits of the Corda protocol.

• New Network Map Service:

  This release introduces the new network map architecture. The network map service has been completely redesigned and implemented to enable future increased network scalability and redundancy, reduced runtime operational overhead, support for multiple notaries, and administration of network compatibility zones (CZ).

  A Corda Compatibility Zone is defined as a grouping of participants and services (notaries, oracles, doorman, network map server) configured within an operational Corda network to be interoperable and compatible with each other.

  We introduce the concept of network parameters to specify precisely the set of constants (or ranges of constants) upon which the nodes within a network need to agree in order to be assured of seamless inter-operation. Additional security controls ensure that all network map data is now signed, thus reducing the power of the network operator to tamper with the map.

  There is also support for a group of nodes to operate locally, which is achieved by copying each node's signed info file to the other nodes' directories. We've added a bootstrapping tool to facilitate this use case.

  Important

  This replaces the Network Map service that was present in Corda 1.0 and Corda 2.0.

  Further information can be found in the changelog, network-map and network-bootstrapper documentation.

• Contract Upgrade

  Support for the upgrading of contracts has been significantly extended in this release.

  Contract states express which attached JARs can define and verify them using _constraints. In older versions the only supported constraint was a hash constraint. This provides similar behaviour as public blockchain systems like Bitcoin and Ethereum, in which code is entirely fixed once deployed and cannot be changed later. In Corda there is an upgrade path that involves the cooperation of all involved parties (as advertised by the states themselves), but this requires explicit transactions to be applied to all states and be signed by all parties.

  Tip

  This is a fairly heavyweight operation. As such, consideration should be given as to the most opportune time at which it should be performed.

  Hash constraints provide for maximum decentralisation and minimum trust, at the cost of flexibility. In Corda 3.0 we add a new constraint, a network parameters constraint, that allows the list of acceptable contract JARs to be maintained by the operator of the compatibility zone rather than being hard-coded. This allows for simple upgrades at the cost of the introduction of an element of centralisation.

  Zone constraints provide a less restrictive but more centralised control mechanism. This can be useful when you want the ability to upgrade an app and you don’t mind the upgrade taking effect “just in time” when a transaction happens to be required for other business reasons. These allow you to specify that the network parameters of a compatibility zone (see network-map) is expected to contain a map of class name to hashes of JARs that are allowed to provide that class. The process for upgrading an app then involves asking the zone operator to add the hash of your new JAR to the parameters file, and trigger the network parameters upgrade process. This involves each node operator running a shell command to accept the new parameters file and then restarting the node. Node owners who do not restart their node in time effectively stop being a part of the network.

  Note

  In prior versions of Corda, states included the hash of their defining application JAR (in the Hash Constraint). In this release, transactions have the JAR containing the contract and states attached to them, so the code will be copied over the network to the recipient if that peer lacks a copy of the app.

  Prior to running the verification code of a contract the JAR within which the verification code of the contract resides is tested for compliance to the contract constraints:

  • For the HashConstraint: the hash of the deployed CorDapp jar must be the same as the hash found in the Transaction.
  • For the ZoneConstraint: the Transaction must come with a whitelisted attachment for each Contract State.

  If this step fails the normal transaction verification failure path is followed.

  Corda 3.0 lays the groundwork for future releases, when contract verification will be done against the attached contract JARs rather than requiring a locally deployed CorDapp of the exact version specified by the transaction. The future vision for this feature will entail the dynamic downloading of the appropriate version of the smart contract and its execution within a sandboxed environment.

  Warning

  This change means that your app JAR must now fit inside the 10mb attachment size limit. To avoid redundantly copying unneeded code over the network and to simplify upgrades, consider splitting your application into two or more JARs - one that contains states and contracts (which we call the app "kernel"), and another that contains flows, services, web apps etc. For example, our Cordapp template is structured like that. Only the first will be attached. Also be aware that any dependencies your app kernel has must be bundled into a fat JAR, as JAR dependencies are not supported in Corda 3.0.

  Future versions of Corda will add support for signature based constraints, in which any JAR signed by a given identity can be attached to the transaction. This final constraint type provides a balance of all requirements: smooth rolling upgrades can be performed without any additional steps or transactions being signed, at the cost of trusting the app developer more and some additional complexity around managing app signing.

  Please see the upgrading-cordapps for more information on upgrading contracts.

• Test API Stability

  A great deal of work has been carried out to refine the APIs provided to test CorDapps, making them simpler, more intuitive, and generally easier to use. In addition, these APIs have been added to the locked list of the APIs we guarantee to be stable over time. This should greatly increase productivity when upgrading between versions, as your testing environments will work without alteration.

  Please see the upgrade-notes for more information on transitioning older tests to the new framework.

Other Functional Improvements

• Clean Node Shutdown

  We, alongside user feedback, concluded there was a strong need for the ability to have a clean inflection point where a node could be shutdown without any in-flight transactions pending to allow for a clean system for upgrade purposes. As such, a flows draining mode has been added. When activated, this places the node into a state of quiescence that guarantees no new work will be started and all outstanding work completed prior to shutdown.

  A clean shutdown can thus be achieved by:

  1. Subscribing to state machine updates
  2. Trigger flows draining mode by rpc.setFlowsDrainingModeEnabled(true)
  3. Wait until the subscription setup as phase 1 lets you know that no more checkpoints are around
  4. Shut the node down however you want

  Note

  Once set, this mode is a persistent property that will be preserved across node restarts. It must be explicitly disabled before a node will accept new RPC flow connections.

• X.509 certificates

  These now have an extension that specifies the Corda role the certificate is used for, and the role hierarchy is now enforced in the validation code. This only has impact on those developing integrations with external PKI solutions; in most cases it is managed transparently by Corda. A formal specification of the extension can be found at see permissioning-certificate-specification.

• Configurable authorization and authentication data sources

  Corda can now be configured to load RPC user credentials and permissions from an external database and supports password encryption based on the Apache Shiro framework. See RPC security management <rpc_security_mgmt_ref> for documentation.

• SSH Server

  Remote administration of Corda nodes through the CRaSH shell is now available via SSH, please see shell for more details.

• RPC over SSL

  Corda now allows for the configuration of its RPC calls to be made over SSL. See corda-configuration-file for details how to configure this.

• Improved Notary configuration

  The configuration of notaries has been simplified into a single notary configuration object. See corda-configuration-file for more details.

  Note

  extraAdvertisedServiceIds, notaryNodeAddress, notaryClusterAddresses and bftSMaRt configs have been removed.

• Database Tables Naming Scheme

  To align with common conventions across all supported Corda and R3 Corda databases some table names have been changed.

  In addition, for existing contract ORM schemas that extend from CommonSchemaV1.LinearState or CommonSchemaV1.FungibleState, you will need to explicitly map the participants collection to a database table. Previously this mapping was done in the superclass, but that makes it impossible to properly configure the table name. The required change is to add the override var participants: MutableSet<AbstractParty>? = null field to your class, and add JPA mappings.

• Pluggable Custom Serializers

  With the introduction of AMQP we have introduced the requirement that to be seamlessly serializable classes, specifically Java classes (as opposed to Kotlin), must be compiled with the -parameter flag. However, we recognise that this isn't always possible, especially dealing with third party libraries in tightly controlled business environments.

  To work around this problem as simply as possible CorDapps now support the creation of pluggable proxy serializers for such classes. These should be written such that they create an intermediary representation that Corda can serialise that is mappable directly to and from the unserializable class.

  A number of examples are provided by the SIMM Valuation Demo in

  samples/simm-valuation-demo/src/main/kotlin/net/corda/vega/plugin/customserializers

  Documentation can be found in cordapp-custom-serializers

Security Auditing

This version of Corda is the first to have had select components subjected to the newly established security review process by R3's internal security team. Security review will be an on-going process that seeks to provide assurance that the security model of Corda has been implemented to the highest standard, and is in line with industry best practice.

As part of this security review process, an independent external security audit of the HTTP based components of the code was undertaken and its recommendations were acted upon. The security assurance process will develop in parallel to the Corda platform and will combine code review, automated security testing and secure development practices to ensure Corda fulfils its security guarantees.

Security fixes

• Due to a potential privacy leak, there has been a breaking change in the error object returned by the notary service when trying to consume the same state twice: NotaryError.Conflict no longer contains the identity of the party that initiated the first spend of the state, and specifies the hash of the consuming transaction id for a state instead of the id itself.

  Without this change, knowing the reference of a particular state, an attacker could construct an invalid double-spend transaction, and obtain the information on the transaction and the party that consumed it. It could repeat this process with the newly obtained transaction id by guessing its output indexes to obtain the forward transaction graph with associated identities. When anonymous identities are used, this could also reveal the identity of the owner of an asset.

Minor Changes

• Upgraded gradle to 4.4.1.

  Note

  To avoid potential incompatibility issues we recommend you also upgrade your CorDapp's gradle plugin to match. Details on how to do this can be found on the official gradle website

• Cash Spending now allows for sending multiple amounts to multiple parties with a single API call

  • documentation can be found within the JavaDocs on TwoPartyTradeFlow.

• Overall improvements to error handling (RPC, Flows, Network Client).

• TLS authentication now supports mixed RSA and ECDSA keys.

• PrivacySalt computation is faster as it does not depend on the OS's entropy pool directly.

• Numerous bug fixes and documentation tweaks.

• Removed dependency on Jolokia WAR file.

Release 2.0

Following quickly on the heels of the release of Corda 1.0, Corda version 2.0 consolidates a number of security updates for our dependent libraries alongside the reintroduction of the Observer node functionality. This was absent from version 1 but based on user feedback its re-introduction removes the need for complicated "isRelevant()" checks.

In addition the fix for a small bug present in the coin selection code of V1.0 is integrated from master.

• Version Bump

Due to the introduction of new APIs, Corda 2.0 has a platform version of 2. This will be advertised in the network map structures and via the versioning APIs.

• Observer Nodes

Adds the facility for transparent forwarding of transactions to some third party observer, such as a regulator. By having that entity simply run an Observer node they can simply receive a stream of digitally signed, de-duplicated reports that can be used for reporting.

Release 1.0

Corda 1.0 is finally here!

This critical step in the Corda journey enables the developer community, clients, and partners to build on Corda with confidence. Corda 1.0 is the first released version to provide API stability for Corda application (CorDapp) developers. Corda applications will continue to work against this API with each subsequent release of Corda. The public API for Corda will only evolve to include new features.

As of Corda 1.0, the following modules export public APIs for which we guarantee to maintain backwards compatibility, unless an incompatible change is required for security reasons:

• core: Contains the bulk of the APIs to be used for building CorDapps: contracts, transactions, flows, identity, node services, cryptographic libraries, and general utility functions.
• client-rpc: An RPC client interface to Corda, for use by both UI facing clients and integration with external systems.
• client-jackson: Utilities and serialisers for working with JSON representations of basic types.

Our extensive testing frameworks will continue to evolve alongside future Corda APIs. As part of our commitment to ease of use and modularity we have introduced a new test node driver module to encapsulate all test functionality in support of building standalone node integration tests using our DSL driver.

Please read corda-api for complete details.

Note

it may be necessary to recompile applications against future versions of the API until we begin offering ABI (Application Binary Interface) stability as well. We plan to do this soon after this release of Corda.

Significant changes implemented in reaching Corda API stability include:

• Flow framework: The Flow framework communications API has been redesigned around session based communication with the introduction of a new FlowSession to encapsulate the counterparty information associated with a flow. All shipped Corda flows have been upgraded to use the new FlowSession. Please read api-flows for complete details.
• Complete API cleanup: Across the board, all our public interfaces have been thoroughly revised and updated to ensure a productive and intuitive developer experience. Methods and flow naming conventions have been aligned with their semantic use to ease the understanding of CorDapps. In addition, we provide ever more powerful re-usable flows (such as CollectSignaturesFlow) to minimize the boiler-plate code developers need to write.
• Simplified annotation driven scanning: CorDapp configuration has been made simpler through the removal of explicit configuration items in favour of annotations and classpath scanning. As an example, we have now completely removed the CordaPluginRegistry configuration. Contract definitions are no longer required to explicitly define a legal contract reference hash. In their place an optional LegalProseReference annotation to specify a URI is used.
• Java usability: All code has been updated to enable simple access to static API parameters. Developers no longer need to call getter methods, and can reference static API variables directly.

In addition to API stability this release encompasses a number of major functional improvements, including:

• Contract constraints: Provides a means with which to enforce a specific implementation of a State's verify method during transaction verification. When loading an attachment via the attachment classloader, constraints of a transaction state are checked against the list of attachment hashes provided, and the attachment is rejected if the constraints are not matched.

• Signature Metadata support: Signers now have the ability to add metadata to their digital signatures. Whereas previously a user could only sign the Merkle root of a transaction, it is now possible for extra information to be attached to a signature, such as a platform version and the signature-scheme used.

  

• Backwards compatibility and improvements to core transaction data structures: A new Merkle tree model has been introduced that utilises sub-Merkle trees per component type. Components of the same type, such as inputs or commands, are grouped together and form their own Merkle tree. Then, the roots of each group are used as leaves in the top-level Merkle tree. This model enables backwards compatibility, in the sense that if new component types are added in the future, old clients will still be able to compute the Merkle root and relay transactions even if they cannot read (deserialise) the new component types. Due to the above, FilterTransaction has been made simpler with a structure closer to WireTransaction. This has the effect of making the API more user friendly and intuitive for both filtered and unfiltered transactions.

• Enhanced component privacy: Corda 1.0 is equipped with a scalable component visibility design based on the above sophisticated sub-tree model and the introduction of nonces per component. Roughly, an initial base-nonce, the "privacy-salt", is used to deterministically generate nonces based on the path of each component in the tree. Because each component is accompanied by a nonce, we protect against brute force attacks, even against low-entropy components. In addition, a new privacy feature is provided that allows non-validating notaries to ensure they see all inputs and if there was a TimeWindow in the original transaction. Due to the above, a malicious user cannot selectively hide one or more input states from the notary that would enable her to bypass the double-spending check. The aforementioned functionality could also be applied to Oracles so as to ensure all of the commands are visible to them.

  

• Full support for confidential identities: This includes rework and improvements to the identity service to handle both well known and confidential identities. This work ships in an experimental module in Corda 1.0, called confidential-identities. API stabilisation of confidential identities will occur as we make the integration of this privacy feature into applications even easier for developers.

• Re-designed network map service: The foundations for a completely redesigned network map service have been implemented to enable future increased network scalability and redundancy, support for multiple notaries, and administration of network compatibility zones and business networks.

Finally, please note that the 1.0 release has not yet been security audited.

We have provided a comprehensive upgrade-notes to ease the transition of migrating CorDapps to Corda 1.0

Upgrading to this release is strongly recommended, and you will be safe in the knowledge that core APIs will no longer break.

Thank you to all contributors for this release!

Milestone 14

This release continues with the goal to improve API stability and developer friendliness. There have also been more bug fixes and other improvements across the board.

The CorDapp template repository has been replaced with a specific repository for Java and Kotlin to improve the experience of starting a new project and to simplify the build system.

It is now possible to specify multiple IP addresses and legal identities for a single node, allowing node operators more flexibility in setting up nodes.

A format has been introduced for CorDapp JARs that standardises the contents of CorDapps across nodes. This new format now requires CorDapps to contain their own external dependencies. This paves the way for significantly improved dependency management for CorDapps with the release of Jigsaw (Java Modules). For those using non-gradle build systems it is important to read cordapp-build-systems to learn more. Those using our cordformation plugin simply need to update to the latest version (0.14.0) to get the fixes.

We've now begun the process of demarcating which classes are part of our public API and which ones are internal. Everything found in net.corda.core.internal and other packages in the net.corda namespace which has .internal in it are considered internal and not for public use. In a future release any CorDapp using these packages will fail to load, and when we migrate to Jigsaw these will not be exported.

The transaction finalisation flow (FinalityFlow) has had hooks added for alternative implementations, for example in scenarios where no single participant in a transaction is aware of the well known identities of all parties.

DemoBench has a fix for a rare but inconvenient crash that can occur when sharing your display across multiple devices, e.g. a projector while performing demonstrations in front of an audience.

Guava types are being removed because Guava does not have backwards compatibility across versions, which has serious issues when multiple libraries depend on different versions of the library.

The identity service API has been tweaked, primarily so anonymous identity registration now takes in AnonymousPartyAndPath rather than the individual components of the identity, as typically the caller will have an AnonymousPartyAndPath instance. See change log for further detail.

Upgrading to this release is strongly recommended in order to keep up with the API changes, removal and additions.

Milestone 13

Following our first public beta in M12, this release continues the work on API stability and user friendliness. Apart from bug fixes and code refactoring, there are also significant improvements in the Vault Query and the Identity Service (for more detailed information about what has changed, see changelog). More specifically:

The long awaited new Vault Query service makes its debut in this release and provides advanced vault query capabilities using criteria specifications (see QueryCriteria), sorting, and pagination. Criteria specifications enable selective filtering with and/or composition using multiple operator primitives on standard attributes stored in Corda internal vault tables (eg. vault_states, vault_fungible_states, vault_linear_states), and also on custom contract state schemas defined by CorDapp developers when modelling new contract types. Custom queries are specifiable using a simple but sophisticated builder DSL (see QueryCriteriaUtils). The new Vault Query service is usable by flows and by RPC clients alike via two simple API functions: queryBy() and trackBy(). The former provides point-in-time snapshot queries whilst the later supplements the snapshot with dynamic streaming of updates. See api-vault-query for full details.

We have written a comprehensive Hello, World! tutorial, showing developers how to build a CorDapp from start to finish. The tutorial shows how the core elements of a CorDapp - states, contracts and flows - fit together to allow your node to handle new business processes. It also explains how you can use our contract and flow testing frameworks to massively reduce CorDapp development time.

Certificate checks have been enabled for much of the identity service. These are part of the confidential (anonymous) identities work, and ensure that parties are actually who they claim to be by checking their certificate path back to the network trust root (certificate authority).

To deal with anonymized keys, we've also implemented a deterministic key derivation function that combines logic from the HMAC-based Extract-and-Expand Key Derivation Function (HKDF) protocol and the BIP32 hardened parent-private-key -> child-private-key scheme. This function currently supports the following algorithms: ECDSA secp256K1, ECDSA secpR1 (NIST P-256) and EdDSA ed25519. We are now very close to fully supporting anonymous identities so as to increase privacy even against validating notaries.

We have further tightened the set of objects which Corda will attempt to serialise from the stack during flow checkpointing. As flows are arbitrary code in which it is convenient to do many things, we ended up pulling in a lot of objects that didn't make sense to put in a checkpoint, such as Thread and Connection. To minimize serialization cost and increase security by not allowing certain classes to be serialized, we now support class blacklisting that will return an IllegalStateException if such a class is encountered during a checkpoint. Blacklisting supports superclass and superinterface inheritance and always precedes @CordaSerializable annotation checking.

We've also started working on improving user experience when searching, by adding a new RPC to support fuzzy matching of X.500 names.

Milestone 12 - First Public Beta

One of our busiest releases, lots of changes that take us closer to API stability (for more detailed information about what has changed, see changelog). In this release we focused mainly on making developers' lives easier. Taking into account feedback from numerous training courses and meet-ups, we decided to add CollectSignaturesFlow which factors out a lot of code which CorDapp developers needed to write to get their transactions signed. The improvement is up to 150 fewer lines of code in each flow! To have your transaction signed by different parties, you need only now call a subflow which collects the parties' signatures for you.

Additionally we introduced classpath scanning to wire-up flows automatically. Writing CorDapps has been made simpler by removing boiler-plate code that was previously required when registering flows. Writing services such as oracles has also been simplified.

We made substantial RPC performance improvements (please note that this is separate to node performance, we are focusing on that area in future milestones):

• 15-30k requests per second for a single client/server RPC connection.
  • 1Kb requests, 1Kb responses, server and client on same machine, parallelism 8, measured on a Dell XPS 17(i7-6700HQ, 16Gb RAM)
• The framework is now multithreaded on both client and server side.
• All remaining bottlenecks are in the messaging layer.

Security of the key management service has been improved by removing support for extracting private keys, in order that it can support use of a hardware security module (HSM) for key storage. Instead it exposes functionality for signing data (typically transactions). The service now also supports multiple signature schemes (not just EdDSA).

We've added the beginnings of flow versioning. Nodes now reject flow requests if the initiating side is not using the same flow version. In a future milestone release will add the ability to support backwards compatibility.

As with the previous few releases we have continued work extending identity support. There are major changes to the Party class as part of confidential identities, and how parties and keys are stored in transaction state objects. See changelog for full details.

Added new Byzantine fault tolerant (BFT) decentralised notary demo, based on the BFT-SMaRT protocol For how to run the demo see: notary-demo

We continued to work on tools that enable diagnostics on the node. The newest addition to Corda Shell is flow watch command which lets the administrator see all flows currently running with result or error information as well as who is the flow initiator. Here is the view from DemoBench:

We also started work on the strategic wire format (not integrated).

Milestone 11

Special thank you to Gary Rowe for his contribution to Corda's Contracts DSL in M11.

Work has continued on confidential identities, introducing code to enable the Java standard libraries to work with composite key signatures. This will form the underlying basis of future work to standardise the public key and signature formats to enable interoperability with other systems, as well as enabling the use of composite signatures on X.509 certificates to prove association between transaction keys and identity keys.

The identity work will require changes to existing code and configurations, to replace party names with full X.500 distinguished names (see RFC 1779 for details on the construction of distinguished names). Currently this is not enforced, however it will be in a later milestone.

• "myLegalName" in node configurations will need to be replaced, for example "Bank A" is replaced with "CN=Bank A,O=Bank A,L=London,C=GB". Obviously organisation, location and country ("O", "L" and "C" respectively) must be given values which are appropriate to the node, do not just use these example values.
• "networkMap" in node configurations must be updated to match any change to the legal name of the network map.
• If you are using mock parties for testing, try to standardise on the DUMMY_NOTARY, DUMMY_BANK_A, etc. provided in order to ensure consistency.

We anticipate enforcing the use of distinguished names in node configurations from M12, and across the network from M13.

We have increased the maximum message size that we can send to Corda over RPC from 100 KB to 10 MB.

The Corda node now disables any use of ObjectInputStream to prevent Java deserialisation within flows. This is a security fix, and prevents the node from deserialising arbitrary objects.

We've introduced the concept of platform version which is a single integer value which increments by 1 if a release changes any of the public APIs of the entire Corda platform. This includes the node's public APIs, the messaging protocol, serialisation, etc. The node exposes the platform version it's on and we envision CorDapps will use this to be able to run on older versions of the platform to the one they were compiled against. Platform version borrows heavily from Android's API Level.

We have revamped the DemoBench user interface. DemoBench will now also be installed as "Corda DemoBench" for both Windows and MacOSX. The original version was installed as just "DemoBench", and so will not be overwritten automatically by the new version.

Milestone 10

Special thank you to Qian Hong, Marek Skocovsky, Karel Hajek, and Jonny Chiu for their contributions to Corda in M10.

A new interactive Corda Shell has been added to the node. The shell lets developers and node administrators easily command the node by running flows, RPCs and SQL queries. It also provides a variety of commands to monitor the node. The Corda Shell is based on the popular CRaSH project and new commands can be easily added to the node by simply dropping Groovy or Java files into the node's shell-commands directory. We have many enhancements planned over time including SSH access, more commands and better tab completion.

The new "DemoBench" makes it easy to configure and launch local Corda nodes. It is a standalone desktop app that can be bundled with its own JRE and packaged as either EXE (Windows), DMG (MacOS) or RPM (Linux-based). It has the following features:

1. New nodes can be added at the click of a button. Clicking "Add node" creates a new tab that lets you edit the most important configuration properties of the node before launch, such as its legal name and which CorDapps will be loaded.
2. Each tab contains a terminal emulator, attached to the pseudoterminal of the node. This lets you see console output.
3. You can launch an Corda Explorer instance for each node at the click of a button. Credentials are handed to the Corda Explorer so it starts out logged in already.
4. Some basic statistics are shown about each node, informed via the RPC connection.
5. Another button launches a database viewer in the system browser.
6. The configurations of all running nodes can be saved into a single .profile file that can be reloaded later.

Soft Locking is a new feature implemented in the vault to prevent a node constructing transactions that attempt to use the same input(s) simultaneously. Such transactions would result in naturally wasted effort when the notary rejects them as double spend attempts. Soft locks are automatically applied to coin selection (eg. cash spending) to ensure that no two transactions attempt to spend the same fungible states.

The basic Amount API has been upgraded to have support for advanced financial use cases and to better integrate with currency reference data.

We have added optional out-of-process transaction verification. Any number of external verifier processes may be attached to the node which can handle loadbalanced verification requests.

We have also delivered the long waited Kotlin 1.1 upgrade in M10! The new features in Kotlin allow us to write even more clean and easy to manage code, which greatly increases our productivity.

This release contains a large number of improvements, new features, library upgrades and bug fixes. For a full list of changes please see changelog.

Milestone 9

This release focuses on improvements to resiliency of the core infrastructure, with highlights including a Byzantine fault tolerant (BFT) decentralised notary, based on the BFT-SMaRT protocol and isolating the web server from the Corda node.

With thanks to open source contributor Thomas Schroeter for providing the BFT notary prototype, Corda can now resist malicious attacks by members of a distributed notary service. If your notary service cluster has seven members, two can become hacked or malicious simultaneously and the system continues unaffected! This work is still in development stage, and more features are coming in the next snapshot!

The web server has been split out of the Corda node as part of our ongoing hardening of the node. We now provide a Jetty servlet container pre-configured to contact a Corda node as a backend service out of the box, which means individual webapps can have their REST APIs configured for the specific security environment of that app without affecting the others, and without exposing the sensitive core of the node to malicious Javascript.

We have launched a global training programme, with two days of classes from the R3 team being hosted in London, New York and Singapore. R3 members get 5 free places and seats are going fast, so sign up today.

We've started on support for confidential identities, based on the key randomisation techniques pioneered by the Bitcoin and Ethereum communities. Identities may be either anonymous when a transaction is a part of a chain of custody, or fully legally verified when a transaction is with a counterparty. Type safety is used to ensure the verification level of a party is always clear and avoid mistakes. Future work will add support for generating new identity keys and providing a certificate path to show ownership by the well known identity.

There are even more privacy improvements when a non-validating notary is used; the Merkle tree algorithm is used to hide parts of the transaction that a non-validating notary doesn't need to see, whilst still allowing the decentralised notary service to sign the entire transaction.

The serialisation API has been simplified and improved. Developers now only need to tag types that will be placed in smart contracts or sent between parties with a single annotation... and sometimes even that isn't necessary!

Better permissioning in the cash CorDapp, to allow node users to be granted different permissions depending on whether they manage the issuance, movement or ledger exit of cash tokens.

We've continued to improve error handling in flows, with information about errors being fed through to observing RPC clients.

There have also been dozens of bug fixes, performance improvements and usability tweaks. Upgrading is definitely worthwhile and will only take a few minutes for most apps.

For a full list of changes please see changelog.