ASN.1 and Interledger

Interledger is an open protocol suite for the exchange of payments across different ledgers (banks, blockchains, crypto currencies, etc.). It is a standard way of bridging financial systems. Like Internet Protocol (IP), it routes “packets of money” across independent payments networks. The Interledger architecture consists of three types of nodes, a sender, a receiver, and a connector. As their names suggest, the sender initiates a payment request for the receiver, and the request is routed through various connectors.

The Interledger protocol suite is divided into layers of protocols each with different responsibilities. The Ledger protocols represent the existing money systems that Interledger connects to. The Interledger Protocol (ILP) is the core protocol of the entire suite. Its packets pass through all participants in the chain, from the sender, through the connectors, to the receiver. ILP is compatible with any type of currency and underlying ledger systems. The Transport layer protocols are used for end-to-end communication between senders and receivers. The protocols at the application layer communicate details outside of the minimum information that is needed to complete a payment.

The protocols used in the Transport and Interledger layers are specified in ASN.1, a standardized syntax notation to define message structures and encodings in a platform-independent way. Interledger messages are encoded according to the ASN.1 Octet Encoding Rules (OER). Using ASN.1 to define and encode protocol messages allows Interledger applications to interoperate irrespective of their choice of platform and programming language. OER encodings are simple, compact, and very easy to parse. ASN.1 tools - commercially licensed as well as open source - are available to assist with implementation.

Interledger uses advanced features of ASN.1 to make future upgrades of the protocols extremely easy to incorporate and fully backward compatible. For example, if Interledger adds another message type to BilateralTransferProtocolPacket (see the ASN.1 excerpt below), they will only need to define the message and add it to CallSet, without worrying about backward compatibility.

CALL ::= CLASS {

    &typeId UInt8 UNIQUE,

    &Type

} WITH SYNTAX {&typeId &Type}

CallSet CALL ::= {

    {1 Response} |

    {2 Error} |

    {3 Prepare} |

    {4 Fulfill} |

    {5 Reject} |

    {6 Message} |

    {7 Transfer} |

    {8 NewMessageType}

}

BilateralTransferProtocolPacket ::= SEQUENCE {

    -- One byte type ID

    type CALL.&typeId ({CallSet}),

    -- Used to associate requests and corresponding responses

    requestId UInt32,

    -- Length-prefixed main data

    data CALL.&Type ({CallSet}{@type})

}

NewMessageType ::= SEQUENCE {

            -- Add message fields here

}

The OSS ASN.1 Tools can be used to implement the Transport and Interledger layer protocols. The Interledger ASN.1 specification is passed to the ASN.1 compiler to generate programming language specific structures or classes. The compiler generated code along with the high performance OSS ASN.1 runtime libraries are used to create applications for  the sender, the receiver, and the connectors. ASN-1Step, a GUI based product, can be used to view, create, and modify Interledger messages.

The OSS ASN.1 Tools include a sample Interledger program which demonstrates how the implementer of Interledger Bilateral Transfer Protocol (BTP) can use the Tools to serialize and parse BTP messages. The sample simulates the communication between two BTP peers and implements two scenarios, a) a payment request is successfully processed, and b) a payment request is rejected because it’s expired.

Please visit OSS website to find more information about the OSS ASN.1 products, to download a trial, and/or to access the online documentation. If you have any questions about using the OSS ASN.1 products in Interledger applications, please contact info@oss.com.