Identity record

Every participant and every bill is named by an identifier the protocol generates, not by an account someone issues. There are two kinds: a NodeId for identities and companies, and a BillId for bills.

Both begin with the prefix bitcr, followed by a single character naming the network the identifier was created on:

CharacterNetwork
mMainnet
tTestnet
TTestnet4
rRegtest
sSignet

Because the network is part of the identifier, a testnet identity and a mainnet identity are not merely distinguishable; they cannot be confused for one another by any code that reads the string.

NodeId

Prefix, network character, and the string representation of a Secp256k1 public key:

PREFIX|NETWORK|Secp256k1PublicKey

On testnet, for example:

bitcrt039180c169e5f6d7c579cf1cefa37bffd47a2b389c8125601f4068c87bea795943

BillId

Prefix, network character, and a base58-encoded SHA-256 hash of the bill's Secp256k1 public key:

PREFIX|NETWORK|Base58(Sha256(Secp256k1PublicKey))

On testnet:

bitcrtGgLTAAVDYaoPC5b45MVzdmMBhTNm5AHtm6izEquzWdDV

A bill has its own key pair, distinct from any participant's. See Bill id and keys.

Nostr npubs

Beyond these internal identifiers, the transport layer addresses participants by Nostr npub. An npub is derived from the same Secp256k1 public key, so it is not a second identity to keep in sync. It is the same key wearing the clothes Nostr expects. See Transport.

Identified and anonymous identities

An identity is one of two types:

  • Ident: an identified party, with the name and address fields described in Field description.
  • Anon: an anonymous party.

Anonymity is not available everywhere. Neither the issuer nor the payer of a bill may be anonymous, which follows from a bill being an enforceable obligation: someone has to be identifiable enough to be held to it. A holder further down the endorsement chain is a different matter.

Companies

A company is addressed by a NodeId in exactly the same format as a person. What differs is the record behind it, and which identity a client is currently acting as. A client can switch between acting as a person and acting as a company.

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