Chain link

A chain link represents a link to an external chain account that has been created by the user to connect their Desmos profile to such accounts. These links can be created either offline or using IBC following the specification described inside the "Create a chain link" section.

Contained data

Here follows the data contained inside a chain link.

User (string)

Represents the Desmos address to which the chain link is associated.

Address (object)

Contains the data of the external chain address. Currently, it can be of two different types:

• Bech32Address to represent Bech32-based addresses
• Base58Address to support Base58-encoded addresses

Proof (object)

Contains the data proving the ownership of the external chain account.

• PubKey (object)

  Contains the data of the public key associated with the external address that is used to verify the ownership of such address.

• Signature (string)

  Represents the hex-encoded signature of the plain text that has been created signing it with the private key associated with the provided public key.

• PlainText (string)

  Represents the hex-encoded plain text value that has been signed with the private key associated with the specified Address in order to generate the signature value.

ChainConfig (object)

Contains the details of the external chain to which the link is associated.

• Name (string)

  Represents the human-readable chain name.

CreationTime (time)

Represents the time in which the link has been created.

Create a chain link

1. Create the ownership proofs

When creating a chain link, you need to provide two different proofs to make sure the link is valid:

1. The proof that you own the external chain account;
2. The proof that you own the Desmos profile to which you want to link.

In order to create a proof, the following steps are needed:

1. Get a generic plain text data to sign;
2. Sign the plain text data using your private key;
3. Assemble the signature, plain text and public key into a Proof object.

Here is an example of a valid proof object encoded using JSON:

{
    "pub_key": {
        "@type": "/cosmos.crypto.secp256k1.PubKey",
        "key": "A58DXR/lXKVkIjLofXgST/OHi+pkOQbVIiOjnTy7Zoqo"
    },
    "signature": "ecc6175e730917fb289d3a9f4e49a5630a44b42d972f481342f540e09def2ec5169780d85c4e060d52cc3ffb3d677745a4d56cd385760735bc6db0f1816713be",
    "plain_text": "cosmos15uc89vnzufu5kuhhsxdkltt38zfx8vcyggzwfm"
}

Note that the pub_key field must be encoded using Protobuf and must be compatible with the public key types that are currently supported by Cosmos. You can see a list of such key types here.

2. Create the link

Once you have created the two ownership proofs, you are now ready to create the link. This can be done in two ways:

1. Using IBC;
2. Using the CLI.

Using IBC

This is the way that you want to use when integrating the Desmos connection from your chain.
To implement the IBC capability of connecting an external account to a Desmos profile, the x/profiles module supports the following packet data type:

LinkChainAccountPacketData

LinkChainAccountPacketData defines the object that should be sent inside a MsgSendPacket when wanting to link an external chain to a Desmos profile using IBC.

type LinkChainAccountPacketData struct {

    // SourceAddress contains the details of the external chain address
    SourceAddress *types.Any `protobuf:"bytes,1,opt,name=source_address,json=sourceAddress,proto3" json:"source_address,omitempty" yaml:"source_address"`
    
    // SourceProof represents the proof of ownership of the source address
    SourceProof Proof `protobuf:"bytes,2,opt,name=source_proof,json=sourceProof,proto3" json:"source_proof" yaml:"source_proof"`
    
    // SourceChainConfig contains the details of the source chain
    SourceChainConfig ChainConfig `protobuf:"bytes,3,opt,name=source_chain_config,json=sourceChainConfig,proto3" json:"source_chain_config" yaml:"source_chain_config"`
    
    // DestinationAddress represents the Desmos address of the profile that should
    // be linked with the external account
    DestinationAddress string `protobuf:"bytes,4,opt,name=destination_address,json=destinationAddress,proto3" json:"destination_address,omitempty" yaml:"destination_address"`
    
    // DestinationProof contains the proof of ownership of the DestinationAddress
    DestinationProof Proof `protobuf:"bytes,5,opt,name=destination_proof,json=destinationProof,proto3" json:"destination_proof" yaml:"destination_proof"`
}

Field	Type	Description
SourceAddress	AddressData	Contains the details of the external address to be linked
SourceProof	Proof	Contains the data to verify the ownership of the external address
SourceChainConfig	ChainConfig	Contains the data of the external chain to be linked
DestinationAddress	string	Desmos address of the profile to which link the external address
DestinationProof	Proof	Proof of ownership of the Desmos profile

Note that the SourceAddress field must be one of the currently supported types:

• Base58Address if the external address is represented by the Base58 encoded public key of the account;
• Bech32Address if the external address is Bech32 encoded.

The overall view is the following:

Using the CLI

You can easily create a chain link using the CLI by running two commands:

1.desmos create-chain-link-json This will start an interactive prompt session allowing you to generate the proper JSON file containing all the linkage information.

2. desmos tx profiles link-chain [/path/to/link_file.json] This will effectively link your Desmos profile to the external chain address. The required argument is the (absolute) path to the file generated using the create-chain-link-json command.