Summary

This DIP describes DiemID, a human-readable identifier for user accounts, and a protocol standard for pre-flight exchange using DiemID to form payment transactions.

Motivation

DiemID provides a convenient method for identifying users within a VASP. DiemID allows VASPs to exchange human-readable identifiers as either the sender or the receiver of peer-to-peer payments, and plays the role of an email address for payments. The benefits of using a DiemID are:

• Compatibility with Diem privacy approach: DiemID's do not appear on-chain and do not enable linking payments from/to the same user. The standard uses a pre-flight off-chain exchange between VASPs to agree on a reference ID. The sending VASP can then submit an on-chain transaction containing only this reference ID and without any potentially identifiable user information.
• Persistent Identifiers: Currently there are no persistent user identifiers in the Diem ecosystem. DiemID establishes a persistent identifier from a VASP's perspective which are not used publicly on-chain.

End-to-End Experience

Below is an example wallet-2-wallet flow using DiemID for transferring money from one user to another.

Prerequisite:

• VASPs get approval from association (via some offline process) on domain name.
• VASPs have access to a storage solution mapping domain IDs to parent VASP address

avasp, 0xf72589b71ff4f8d139674a3f7369c69b

bvasp, 0xc5ab123458df0003415689adbb47326d

An Example P2P Transaction Flow:

• Bob wants to receive funds from Alice
• Alice has an account with VASP A: alice@avasp
• Bob has an account with VASP B: bob@bvasp
• VASP A contacts VASP B via an off-chain API with the sender identifier alice@avasp and requests a reference_id, rb
• VASP A constructs a transaction with the specified amount and the reference_id rb and submits it to the Diem network
• VASP B receives a transaction with metadata containing rb, deposits the amount in Bob's account. (VASP B may use Alice’s DiemID for its own record keeping or seek receipt confirmation from Bob.)

DiemID Format

Diem defines globally unique identifiers to facilitate transacting on the Diem Payment Network. As Diem stores no personally identifiable information on-chain, these identifiers are exchanged during the off-chain process between two VASPs to identify a distinct source and destinations within their respective VASPs in order to produce a reference_id that can be stored on-chain. The format of identifiers is [user_identifier]@[vasp_domain_identifier]

Example: alice@avasp

• user_identifier is a reusable identifier that represents either the source or destination end-user of a payment transaction. It is unique to per user at VASP level. Specification:
  • Case insensitive
  • Valid regular expression: ^[a-zA-Z0-9][a-zA-Z0-9.]*$
  • Maximum length: 64 characters
• vasp_domain_identifier is a unique string that is mapped to a VASP defined in DIP-182

We are starting with a small character set to keep it compatible with most naming schemes, but may add on to the set in the future.

On-chain Domain Resolution

Given a receiver's DiemID, bob@bvasp, the sender VASP uses its vasp_domain_identifier (bvasp) to look up the receiving VASP's on-chain address using the on-chain domain resolution process defined in DIP-182.

ReferenceID Exchange

Once the sender VASP gets the receiving VASP's address using on-chain domain lookup, the sender VASP initiates a reference ID exchange as defined in DIP-183 in order settle on a unique reference ID and submit the transaction on-chain.

The format of the command is:

{

"_ObjectType": "CommandRequestObject",

"command_type": "SenderInitiatedReferenceIDExchange",

"command": {

"_ObjectType": "SenderInitiatedReferenceIDExchange",

"sender": "alice@avasp",

"sender_address": "dm1pptdxvfjck4jyw3rkfnm2mnd2t5qqqqqqqqqqqqq305frg",

"receiver": "bob@bvasp",

"reference_id": "5b8403c9-86f5-3fe0-7230-1fe950d030cb",

},

"cid": "12ce83f6-6d18-0d6e-08b6-c00fdbbf085a",

}

The format of the success response is:

{

"_ObjectType": "CommandResponseObject",

"status": "success",

"result": {

"_ObjectType": "SenderInitiatedReferenceIDExchangeResponse",

"receiver_address": "dm1p7ujcndcl7nudzwt8fglhx6wxn08kgs5tm6mz4us2vfufk",

},

"cid": "12ce83f6-6d18-0d6e-08b6-c00fdbbf085a",

}

Once the reference ID exchange is done and two VASPs have settled on a reference ID, the sender VASP uses that reference ID to create a p2p transaction with PaymentMetadata and submits the transaction on-chain.