WebWallet - Primitives

Primitives are building blocks for assembling more expressive data structures. Transactions are made of inputs and outputs, where input IOUs contain digital signatures on their cryptographic hashes that must be verified with the appropriate public keys, and output counters for each address-countspace pair can later be referenced by transaction pointers for spending.

Cryptography

WebWallet uses cryptographic hashes, digital signatures and public keys to represent consent about debts in the form of IOUs. They are used to build conventions for verifying the integrity and authenticity of transaction documents, both for clearing transaction requests and auditing transaction records.

• Hashes
  Cryptographic hashes are one-way functions that generate an output string with the same number of characters regardless of the input size. The next example shows the SHA-256 digest of the string "webwallet":

  90b69feb03ef3af84da763c2183d8a408ea961b6cdce7e250144ba7c154be307
  

• Signatures
  For the purpose of generality, digital signatures are always represented as objects in order to make their properties explicit, such as the signature algorithm. However, the next example only shows the value of an ed25519 signature:

  304402200813081fe53a01aa685327d41b4fa6325adab4dfb47d67ec651154c3ef19b8090220036fe45c4b3635b30240da5ce8264348d452ee80733014fa170b569dc1133f39
  

• Public Keys
  Since signature verification is generalized to support multiple algorithms, WebWallet supports different types of public keys. The next example shows an ed25519 compressed public key:

  03596a0b6e0d8ac185d28d9dccb8f8f1b262704d871a6c10a1eaa1234a034d1f80
  

Identification

Besides using regular domain names for transaction clearing providers (e.g. wallet.example.com), WebWallet uses three types of identifiers for information spaces and the elements within them: addresses, countspaces and transactions.

• Addresses
  An address is an identifier for a collection of counters whose balances are controlled by the same cryptographic credentials. A counter is a data structure that contains properties of a numeric value, such as its unit of account and the constraints for modifying it. Addresses are generated by encoding a cryptographic hash derived from one or more public keys.

  wS1EU4AtgzD6VDtsrJyGKXmkQdvkWt9Qeq
  

• Countspaces
  A countspace (i.e. currency) is a namespace for uniquely identified counters whose numeric values are denominated in the same unit of account. Since any address can issue its own unit of account by signing IOUs denominated in its own identifier, address and countspace identifiers look exactly the same, as shown by the examples above and below.

  wS1EU4AtgzD6VDtsrJyGKXmkQdvkWt9Qeq
  

• Transactions A transaction is a document that describes operations on counters based on references to previous results and instructions to modify their values. Transactions are identified by their cryptographic hashes, which are also represented as objects in order to make their properties explicit, such as the hash function. The example below shows another SHA-256 hash:

  ca978112ca1bbdcafac231b39a23dc4da786eff8147c4e72b9807785afee48bb
  

Accounting

WebWallet's accounting model borrows design elements from Bitcoin, including the notion of inputs and outputs. However, it differs greatly in aspects such as modeling inputs as time-bound IOUs, referencing previous outputs from current outputs (not from inputs), allowing negative balances and supporting multiple units of account.

• Inputs
  WebWallet transaction inputs are IOUs. An IOU is a cryptographically signed document that acknowledges a debt and authorizes a transaction to clear it. IOU claims basically describe who (sub) owes what (amt, cru) to whom (aud), when (nbf, exp) and where (iss). Other claims are used for reference or security purposes, such as detecting replay attacks (nce).

  | PROPERTY | DESCRIPTION | EXAMPLE | | :--- | :--- | :--- | | iss (issuance domain) | transaction clearing domain | "wallet.example.com" | | sub (subject) | source address, sender | "wS1EU4AtgzD6VDtsrJ..." | | aud (audience) | target address, receiver | "wT99yCRnoYrN3KvTte..." | | amt (amount) | transaction amount | "100.0" | | cru (unit of account) | countspace identifier | "wS1EU4AtgzD6VDtsrJ..." | | nce (nonce) | random value for replay attacks | "r4nd0mV41u3" | | nbf (notBefore) | threshold date for clearing | "2009-01-03T02:10:00.000Z" | | exp (expires) | expiration date | "2016-03-14T09:26:53.589Z" |

• Outputs
  WebWallet transaction outputs are counters that aggregate the resulting balance (bal) of each address (adr) in each countspace (cru) after performing the operations described by the inputs. Outputs can reference previous outputs (pre) to be used as initial conditions, and must satisfy constraints such as the balance limits (lim) in order to be valid.

  | PROPERTY | | VALUE | | :--- | :--- | :--- | | adr (address) | output owner | "wS1EU4AtgzD6VDtsrJ..." | | bal (balance) | output balance | "100.0" | | cru (unit of account) | countspace identifier | "wS1EU4AtgzD6VDtsrJ..." | | lim (limits) | balance constraints | {"low": "0", "upp": Infinity} | | pre (previous) | previous outputs spent | ["hash::index", ...] |

• Pointers
  Transaction pointers are compound identifiers used to make reference to a specific output within a transaction, and are made of two parts separated by a double semicolon ("::"): a transaction hash and an index of an outputs array. When they are listed in the "pre" array property of a transaction output, it means that the transaction is spending that previous output.

  ca978112ca1bbdcafac231b39a23dc4da786eff8147c4e72b9807785afee48bb::1   (hash::index)