DIDCOMM

Last updated on Jan 20, 2023

I. Introduction

A. Explanation of the DIDComm protocol

Decentralized identity (DID) is a rapidly growing field that aims to give individuals more control over their personal information and online identity. At the core of this movement is the DIDComm protocol, which enables secure, peer-to-peer messaging between decentralized systems.

DIDComm, short for Decentralized Identifier Communication protocol, is a set of specifications and standards for secure messaging within the decentralized identity ecosystem. It allows for the exchange of verifiable claims and credentials between decentralized systems, such as self-sovereign identity wallets and decentralized apps (dApps). This enables individuals to share their personal information and credentials with others in a secure and private manner.

One of the key features of DIDComm is its use of end-to-end encryption. This means that the content and metadata of messages are protected from third-party eavesdropping. Additionally, DIDComm allows for the creation of trust relationships between peers, enabling verifiable claims and credentials to be shared without the need for a centralized authority.

DIDComm is built on top of the Interplanetary File System (IPFS) and the Interledger Protocol (ILP), which provide the underlying infrastructure for decentralized storage and value transfer. This enables DIDComm to work seamlessly with other decentralized systems, such as blockchain networks, and allows for the creation of new use cases that were not possible with traditional messaging protocols.

One example of a use case for DIDComm is in the field of decentralized finance (DeFi). A user can use their DID to create a decentralized lending platform, and share their creditworthiness with a lender, without the need for a centralized credit bureau.

Another example is in the field of personal data management, where a user can share their personal data with a service provider in a secure and private manner, without having to go through a centralized intermediary.

In summary, the DIDComm protocol is a key component in the decentralized identity ecosystem, allowing for secure, peer-to-peer messaging between decentralized systems. It is built on top of decentralized infrastructure, which enables interoperability with other decentralized systems and opens the door to new use cases in fields such as DeFi and personal data management.

B. Importance of the protocol in the decentralized identity ecosystem

Decentralized identity (DID) is a rapidly growing field that aims to give individuals more control over their personal information and online identity. At the core of this movement is the DIDComm protocol, which plays a crucial role in the decentralized identity ecosystem.

The DIDComm protocol is a set of specifications and standards for secure, peer-to-peer messaging within the decentralized identity ecosystem. It allows for the exchange of verifiable claims and credentials between decentralized systems, such as self-sovereign identity wallets and decentralized apps (dApps).

One of the main advantages of DIDComm is its ability to provide secure communication between decentralized systems. By using end-to-end encryption, the content and metadata of messages are protected from third-party eavesdropping. This ensures that personal information and credentials are kept private and secure.

Another important aspect of DIDComm is its ability to facilitate trust relationships between peers. This is achieved through the use of verifiable claims and credentials, which can be shared without the need for a centralized authority. This allows individuals to share their personal information and credentials with others in a secure and private manner, enabling new use cases in fields such as decentralized finance (DeFi) and personal data management.

Furthermore, DIDComm is built on top of decentralized infrastructure, such as the Interplanetary File System (IPFS) and the Interledger Protocol (ILP), which provides the underlying infrastructure for decentralized storage and value transfer. This enables DIDComm to work seamlessly with other decentralized systems, such as blockchain networks, and allows for the creation of new use cases that were not possible with traditional messaging protocols.

II. What is the DIDComm protocol?

A. Definition and explanation of DIDComm

DIDComm, short for Decentralized Identifier Communication protocol, is a set of specifications and standards for secure, peer-to-peer messaging within the decentralized identity ecosystem. It is designed to enable the exchange of verifiable claims and credentials between decentralized systems, such as self-sovereign identity wallets and decentralized apps (dApps).

One of the key features of DIDComm is its use of end-to-end encryption, which ensures that the content and metadata of messages are protected from third-party eavesdropping. This ensures that personal information and credentials are kept private and secure.

DIDComm is built on top of decentralized infrastructure, such as the Interplanetary File System (IPFS) and the Interledger Protocol (ILP), which provides the underlying infrastructure for decentralized storage and value transfer. This enables DIDComm to work seamlessly with other decentralized systems, such as blockchain networks, and allows for the creation of new use cases that were not possible with traditional messaging protocols.

DIDComm also supports the use of Decentralized Identifiers (DIDs), a new type of identifier that allows individuals to be in control of their own digital identity. DIDs are globally unique, permanent, and resolvable identifiers that are created and controlled by the individual, rather than a centralized authority.

In summary, DIDComm is a protocol that enables secure, peer-to-peer messaging in the decentralized identity ecosystem. It allows for the exchange of verifiable claims and credentials between decentralized systems, built on top of decentralized infrastructure and support the use of Decentralized Identifiers, which enables interoperability with other decentralized systems and opens the door to new use cases in fields such as DeFi and personal data management.

B. How it relates to Decentralized Identifiers (DIDs)

Decentralized Identifiers (DIDs) and the DIDComm protocol are closely related, as they both play a crucial role in the decentralized identity ecosystem.

A DID is a globally unique, permanent, and resolvable identifier that is created and controlled by the individual, rather than a centralized authority. It allows individuals to be in control of their own digital identity and to share their personal information and credentials with others in a secure and private manner.

The DIDComm protocol, on the other hand, is a set of specifications and standards for secure, peer-to-peer messaging within the decentralized identity ecosystem. It enables the exchange of verifiable claims and credentials between decentralized systems, such as self-sovereign identity wallets and decentralized apps (dApps).

DIDComm supports the use of DIDs as the identifier for the endpoints in the protocol communication. This means that when two parties want to communicate using the DIDComm protocol, they use their DIDs as the identifier for their endpoints. The use of DIDs in DIDComm allows the parties to have a verifiable trust relationship, and to prove the authenticity of their communications.

Additionally, DIDComm allows for the exchange of verifiable claims and credentials between decentralized systems, which can be used to prove the authenticity of the DIDs. This is important for building trust in the decentralized identity ecosystem, as it ensures that the parties are who they claim to be.

In summary, DIDs and the DIDComm protocol are closely related, as they both play a crucial role in the decentralized identity ecosystem. DIDs provide a secure and private way for individuals to control their digital identity, while the DIDComm protocol enables the exchange of verifiable claims and credentials between decentralized systems. The use of DIDs in DIDComm allows for the creation of trust relationships between peers, and to prove the authenticity of their communications.

C. Comparison to traditional messaging protocols

The DIDComm protocol offers several advantages over traditional messaging protocols that make it well suited for decentralized systems. Some key differences include:

Decentralized Identifiers (DIDs): The protocol uses DIDs to identify parties, rather than traditional centralized identifiers such as IP addresses or email addresses. This allows for greater privacy and security, as parties have control over their own identities and can share them on a need-to-know basis.
Public key encryption: The protocol uses public key encryption to establish secure connections and encrypt messages, rather than traditional symmetric key encryption. This allows for greater security and flexibility, as parties can have multiple public keys and can rotate them as needed.
Secure routing: The protocol includes a routing feature that allows for the secure routing of messages through multiple intermediaries. This allows for greater scalability and resilience, as messages can be routed through different paths depending on the network conditions.
Multi-party messaging: The protocol supports multi-party messaging, allowing multiple parties to communicate with each other simultaneously. This allows for greater collaboration and coordination between parties, and can enable new use cases such as decentralized marketplaces.
Customizable message types: The protocol supports the creation of custom message types, which can be used to implement specific functionality in an application. This allows for greater flexibility and customization, and can enable new use cases such as decentralized voting systems.

In summary, the DIDComm protocol offers several advantages over traditional messaging protocols, including decentralized identifiers, public key encryption, secure routing, multi-party messaging and customizable message types. These features make it well suited for decentralized systems and enable new use cases and applications that were not possible with traditional messaging protocols.

III. Key features of the DIDComm protocol

A. Secure end-to-end encryption

The DIDComm protocol is different from traditional messaging protocols in a number of ways. Here are some key differences:

End-to-end encryption: DIDComm uses end-to-end encryption to protect the content and metadata of messages from third-party eavesdropping. This ensures that personal information and credentials are kept private and secure. Traditional messaging protocols, on the other hand, may not have built-in encryption or may rely on centralized encryption, which can be less secure.
Peer-to-peer: DIDComm is designed for peer-to-peer communication, meaning that messages are sent directly between the sender and receiver, without the need for a centralized intermediary. Traditional messaging protocols, such as email and SMS, rely on centralized servers to route messages.
Decentralized infrastructure: DIDComm is built on top of decentralized infrastructure, such as the Interplanetary File System (IPFS) and the Interledger Protocol (ILP), which provides the underlying infrastructure for decentralized storage and value transfer. Traditional messaging protocols, on the other hand, rely on centralized servers for storage and routing.
Verifiable Claims: DIDComm enables the exchange of verifiable claims and credentials between decentralized systems, which can be used to prove the authenticity of the DIDs. Traditional messaging protocols do not have this feature, and rely on centralized authorities to authenticate users.
Interoperability: DIDComm is built on top of decentralized infrastructure, which enables interoperability with other decentralized systems, such as blockchain networks. Traditional messaging protocols are not as easily interoperable and often rely on proprietary systems.

DIDComm protocol is different from traditional messaging protocols in that it provides end-to-end encryption, is peer-to-peer, is built on top of decentralized infrastructure, enables the exchange of verifiable claims, and is interoperable with other decentralized systems. These differences make DIDComm a more secure, private and interoperable protocol compared to traditional messaging protocols.

B. Verifiable claims and credentials

Verifiable claims and credentials are an important aspect of the DIDComm protocol, as they allow for the creation of trust relationships between peers in the decentralized identity ecosystem.

A verifiable claim is a statement about an individual or an entity, such as their age, address, or qualifications. It is signed by a trusted authority, such as a government agency or educational institution, and can be verified by anyone who receives it.

A credential, on the other hand, is a collection of verifiable claims that are issued to an individual or entity. It can include multiple claims, such as a person’s name, age, address, and qualifications. Credentials can be used to prove an individual’s identity, such as in the case of a driver’s license or passport.

In the context of the DIDComm protocol, verifiable claims and credentials can be shared between decentralized systems, such as self-sovereign identity wallets and decentralized apps (dApps), without the need for a centralized authority. This allows individuals to share their personal information and credentials with others in a secure and private manner, and enables new use cases in fields such as decentralized finance (DeFi) and personal data management.

Additionally, the DIDComm protocol allows for the proof of authenticity of the claims and credentials by using decentralized infrastructure, such as blockchain networks, and digital signatures, which ensures that the claims are valid and issued by a trusted authority.

Verifiable claims and credentials are an important aspect of the DIDComm protocol, as they allow for the creation of trust relationships between peers in the decentralized identity ecosystem. They enable the exchange of personal information and credentials between decentralized systems in a secure and private manner and can be verified for authenticity using decentralized infrastructure.

C. Interoperability with other decentralized systems

Interoperability is a crucial aspect of the decentralized identity ecosystem, as it allows different systems and platforms to work together seamlessly. The DIDComm protocol is built on top of decentralized infrastructure, such as the Interplanetary File System (IPFS) and the Interledger Protocol (ILP), which enables interoperability with other decentralized systems.

One of the key features of the DIDComm protocol is its ability to communicate with other decentralized systems using the same protocol. This means that decentralized systems, such as self-sovereign identity wallets and decentralized apps (dApps), can communicate with each other without the need for a centralized intermediary. This enables new use cases and applications that were not possible with traditional centralized systems.

For example, a decentralized lending platform can use DIDComm to communicate with a decentralized identity wallet, allowing a user to share their creditworthiness with a lender, without the need for a centralized credit bureau. This enables new financial services and opportunities for individuals who may not have access to traditional financial services.

Additionally, the DIDComm protocol enables interoperability with blockchain networks, which allows for the creation of verifiable claims and credentials that can be shared between different blockchain networks. This enables the creation of cross-chain applications and services that were not possible with traditional centralized systems.

IV. How does the DIDComm protocol work?

A. Message structure and format

The message structure and format of the DIDComm protocol is designed to be simple and flexible, allowing for easy implementation and integration with other systems.

A DIDComm message is composed of three main parts: the header, the body, and the signature.

The header contains metadata about the message, such as the sender's DID, the recipient's DID, the type of message, and the message ID. The header also includes information about the message's routing and handling, such as the message's priority and expiration date.

The body of the message contains the actual payload of the message, such as the verifiable claims and credentials being exchanged. The body can be in any format, such as JSON or CBOR, as long as it is agreed upon by the sender and the recipient.

The signature is a digital signature that is used to verify the authenticity of the message and the sender. The signature is generated using the sender's private key and is verified using the sender's public key.

B. Connection establishment

Connection establishment is a crucial aspect of the DIDComm protocol, as it allows two parties to establish a secure and private communication channel.

The process of connection establishment begins with the exchange of connection invitations. A connection invitation is a message that contains information about the sender's DID and public key, as well as the desired communication settings.

Once the connection invitation is received, the recipient verifies the authenticity of the sender's DID and public key, and then sends a connection request message. The connection request message contains information about the recipient's DID and public key, and is used to establish the communication channel.

After the connection request is received, the sender verifies the authenticity of the recipient's DID and public key, and then sends a connection response message. The connection response message confirms the establishment of the communication channel.

The communication channel is then encrypted using the shared keys exchanged during the connection establishment process. This ensures that the content and metadata of the messages exchanged over the channel are protected from third-party eavesdropping.

In summary, Connection establishment is a crucial aspect of the DIDComm protocol. It allows two parties to establish a secure and private communication channel through the exchange of connection invitations, connection request and connection response messages. The process ensures that the authenticity of the parties is verified, and the communication channel is encrypted to protect the content and metadata of the messages.

C. Handling multiple connections

The DIDComm protocol allows for handling multiple connections with different parties simultaneously. The protocol separates the connection management from the message handling, making it possible for a single party to have multiple connections with different parties at the same time.

Each connection is established independently, with its own unique connection identifier. This allows the parties to send and receive messages over multiple connections in parallel.

When sending a message, the sender specifies the connection identifier of the intended recipient. This ensures that the message is delivered to the correct recipient, even if the sender has multiple connections with different parties.

On the recipient side, the protocol allows for the handling of multiple incoming connections. Each incoming message is associated with a specific connection, and can be processed independently. This allows the recipient to process messages from multiple senders in parallel.

D. Handling message replies

The DIDComm protocol allows for handling message replies in a simple and efficient way.

When sending a message, the sender can include a reply thread ID in the header of the message. The reply thread ID is a unique identifier that is used to track the conversation thread. When the recipient receives the message, they can include the same reply thread ID in the header of their reply. This allows the sender to easily match the reply to the original message.

The protocol also includes an option to add a forward thread ID, which allows a third party to forward the message and still keep the threading intact, allowing the recipient to understand the context of the message.

The recipient can also include a status code in the header of the reply message, which indicates the result of the processing of the original message. For example, a status code of "OK" indicates that the message was processed successfully, while a status code of "Error" indicates that an error occurred during the processing of the message.

V. Implementing the DIDComm protocol

A. Required libraries and tools

To use the DIDComm protocol in your application, you will need to use the libraries and tools that are designed to support it. Here are some of the key libraries and tools that you will likely need to use:

DIDComm library: This library provides the core functionality of the DIDComm protocol, including message handling, encryption and signature. It can be used to implement the protocol in your application.
DID Resolver: A library that enables resolution of Decentralized Identifiers (DIDs) to their associated public keys, and other relevant information, is needed to implement the protocol.
DID Auth: A library that enables to perform authentication and authorization of parties involved in the communication.
Interplanetary File System (IPFS): A decentralized, peer-to-peer file system that is used to store and retrieve data in a decentralized manner. It is used by the DIDComm protocol to store and retrieve message payloads.
Interledger Protocol (ILP): A protocol for sending and receiving payments across different ledgers. It is used by the DIDComm protocol to facilitate value transfer between parties.
Programming Language library: Specific libraries for your preferred programming language, such as JavaScript, Python, Rust, Go, etc. that implement the DIDComm protocol, will be needed.

B. Setting up a DIDComm messaging system

Setting up a DIDComm messaging system involves several steps, including creating a new connection, establishing the communication channel, and sending and receiving messages. Here is an overview of the process:

Connection establishment: The first step is to establish a connection between the sender and the recipient. This involves the exchange of connection invitations, connection requests, and connection responses. These messages contain information about the sender's and recipient's DIDs and public keys, and are used to establish a secure and private communication channel.
Creating a new connection: Each connection is established independently and has its own unique connection identifier. This allows the parties to send and receive messages over multiple connections in parallel.
Establishing the communication channel: Once the connection is established, the communication channel is encrypted using the shared keys exchanged during the connection establishment process. This ensures that the content and metadata of the messages exchanged over the channel are protected from third-party eavesdropping.
Sending and receiving messages: After the communication channel is established, the sender can send messages to the recipient by including the connection identifier in the header of the message. The recipient can then receive and process the messages using the same connection identifier.
Handling message replies: The DIDComm protocol allows for handling message replies in a simple and efficient way by using reply thread IDs and forward thread IDs. This allows the sender and recipient to easily match the reply to the original message and understand the context of the message.
Implementing libraries: To implement the protocol in your application, you will need to use libraries such as DIDComm library, DID Resolver, DID Auth, Interplanetary File System (IPFS), Interledger Protocol (ILP) and specific libraries for your preferred programming language.

C. Sending and receiving messages

Once a connection is established using the DIDComm protocol, parties can send and receive messages in a secure and private manner. Here is an overview of the process of sending and receiving messages:

Preparing the message: The sender creates the message by creating a header, body and signature. The header contains information about the sender's DID, the recipient's DID, the type of message, and the message ID. The body contains the actual payload of the message, such as verifiable claims and credentials. The signature is a digital signature that is used to verify the authenticity of the message and the sender.
Sending the message: The sender then sends the message by including the connection identifier in the header of the message. This ensures that the message is delivered to the correct recipient, even if the sender has multiple connections with different parties.
Receiving the message: The recipient receives the message and processes it by verifying the authenticity of the sender's DID and public key, and decrypting the message using the shared keys from the connection establishment process.
Handling message replies: The recipient can reply to the message by including the same reply thread ID in the header of their reply. This allows the sender to easily match the reply to the original message. Additionally, the recipient can include a status code in the header of the reply message, which indicates the result of the processing of the original message.
Closing the connection: When the parties are done communicating, they can close the connection by sending a close connection message. This terminates the communication channel and deletes the shared keys.

In summary, Sending and receiving messages using the DIDComm protocol involves preparing the message by creating a header, body and signature, sending the message by including the connection identifier in the header, receiving the message by verifying the authenticity

D. Advanced features and customization options

The DIDComm protocol offers several advanced features and customization options that allow for more advanced use cases and applications. Some of these features include:

Secure routing: The protocol includes a routing feature that allows for the secure routing of messages through multiple intermediaries. This can be useful in situations where a sender and recipient are not directly connected, but need to communicate through a network of intermediaries.
Multi-party messaging: The protocol supports multi-party messaging, allowing multiple parties to communicate with each other simultaneously. This can be useful in situations where multiple parties need to collaborate on a project or task.
Customizable message types: The protocol supports the creation of custom message types, which can be used to implement specific functionality in an application. For example, a custom message type can be used to implement a voting system in a decentralized application.
Support for value transfer: The protocol supports value transfer between parties, which can be used to facilitate financial transactions and other use cases.
Support for smart contracts: The protocol supports the integration of smart contracts, which can be used to automate complex processes and enforce rules in a decentralized application.

VI. Use case examples

A. Description of specific use cases

The DIDComm protocol can be used in a wide range of use cases, including:

Decentralized Identity Management: The protocol can be used to enable self-sovereign identity, where individuals have control over their own personal data and can share it with others on a need-to-know basis. This use case is particularly useful in the financial services, healthcare, and government sectors, where secure and private sharing of personal data is critical.
Decentralized Finance: The protocol can be used to enable peer-to-peer financial transactions and enable new financial services that were not possible with traditional centralized systems. For example, it can be used to facilitate lending and borrowing without the need for a centralized credit bureau.
Supply Chain Management: The protocol can be used to enable secure and private sharing of information between different parties in a supply chain, such as manufacturers, suppliers, and logistics providers. This can improve transparency and efficiency in the supply chain, and help prevent fraud and counterfeiting.
Health Care: The protocol can be used to enable secure and private sharing of health data between patients, doctors, and hospitals. This can improve the delivery of healthcare services and enable new use cases such as remote consultations and telemedicine.
Internet of Things (IoT): The protocol can be used to enable secure and private communication between IoT devices, allowing them to share data and collaborate on tasks. This can enable new use cases such as smart homes and cities, and autonomous vehicles.
Decentralized marketplaces: The protocol can be used to enable secure and private transactions between parties in a decentralized marketplace. This can be beneficial for reducing fraud and increasing trust between parties.

B. Code examples

Code examples for implementing the DIDComm protocol will vary depending on the programming language and libraries being used. However, here is a general example of how the protocol might be implemented in Python using the py-did-comm library:

Establishing a connection:

from py_did_comm.protocol.connection import Connection

# Create a new connection
conn = Connection()

# Send a connection invitation
conn.send_invitation()

# Receive and process a connection request
conn.process_request()

# Send a connection response
conn.send_response()

Sending a message:

from py_did_comm.protocol.message import Message

# Create a new message
msg = Message(conn_id=conn.id, content={"hello": "world"})

# Send the message
msg.send()

Receiving a message:

# Receive and process a message
msg = conn.receive()

# Print the message content
print(msg.content)

Handling message replies:

# Send a reply to the message
msg.reply(content={"response": "acknowledged"})

Closing the connection:

# Close the connection
conn.close()

VII. Conclusion

A. Recap of key points

DIDComm is a messaging protocol for decentralized systems that enables secure and private communication between parties.
It uses Decentralized Identifiers (DIDs) and public key encryption to establish secure connections between parties.
The protocol allows for handling multiple connections and message replies in a simple and efficient way.
It also supports advanced features such as secure routing, multi-party messaging, customizable message types, and support for value transfer and smart contracts.
The protocol can be used in a wide range of use cases such as decentralized identity management, decentralized finance, supply chain management, healthcare, IoT, and decentralized marketplaces.
Implementing the protocol requires the use of libraries such as DIDComm library, DID Resolver, DID Auth, Interplanetary File System (IPFS), Interledger Protocol (ILP) and specific libraries for the preferred programming language.
Code examples for implementing the protocol will vary depending on the programming language and libraries being used.
The protocol is an important step towards interoperability and trust between different decentralized systems.

B. Additional resources for learning more about the DIDComm protocol

There are several resources available for learning more about the DIDComm protocol and how to implement it in your application:

The official website for the protocol: https://github.com/hyperledger/aries-rfcs#aries-protocols
The py-did-comm library: a Python implementation of the protocol that can be used to easily implement the protocol in a Python application.
The Hyperledger Aries documentation: provides detailed information about the protocol and how to implement it in different programming languages.
The Decentralized Identity Foundation (DIF) website: an organization dedicated to advancing the development and adoption of decentralized identity technologies.
DIDComm community: a community of developers and researchers working on the protocol and other decentralized technologies.
Aries Blogs: a collection of technical blogs on the protocol and how to use it to build decentralized applications.
Aries GitHub Repo: a collection of code samples and documentation on the protocol.
Videos and Webinars: There are a lot of webinars and videos on youtube and other platforms that explain the protocol and its implementation in detail.

These resources will provide you with more information about the protocol and help you understand how to implement it in your application.

C. Call to action for implementing the DIDComm protocol in your own projects

If you are interested in implementing the DIDComm protocol in your own project, here are a few steps you can take to get started:

Familiarize yourself with the basics of the protocol by reading the official documentation and experimenting with the code samples provided.
Choose a programming language and libraries that you are comfortable working with and begin experimenting with the protocol by building simple applications.
Join the DIDComm community to connect with other developers and researchers who are working on the protocol and can provide guidance and support.
Participate in online forums and discussion groups to learn more about the protocol and get answers to your questions.
Explore the various use cases of the protocol and think about how it can be applied to your own project or industry.
Test and experiment with the protocol to understand its capabilities and limitations, and identify areas for improvement.
Share your experience and findings with the community, and contribute to the development of the protocol by submitting bug reports, feature requests, and code improvements.