# Digital Token
[ISO 24165](https://www.iso.org/standard/80601.html) introduces a common language for digital currencies. Up until now, digital currencies ("crypto") have been an uncomfortable fit into the world of currencies which are governed by [ISO 4217](https://en.wikipedia.org/wiki/ISO_4217).
`ISO 4217` does allow for private use currencies, however in common use several crypto currencies use unnoficial `ISO 4217` codes that clash with the standard.
The introduction of `ISO 24165` (and is relationship to [ISO 20022](https://www.iso20022.org)) creates a framework for the identification and standardisation of digital tokens.
In addition, the [Digital Token Identification Foundation (DTIF)](https://dtif.org) has been formed to operate a [registry](https://dtif.org/token-registry-search/) of tokens with [downloadable data](https://dtif.org/download-dti-registry/) making it easy to access and integrate the data into applications.
This library provides a means to download and access the digital token registry. One application is the upcoming integration of `digital_token` into [ex_money](https://github.com/kipcole9/money) providing money operations on both ISO 4217 currencies and ISO 24165 digital tokens.
### Digital Token Identifier Format
The basic number is eight characters (alphanumeric) in length but excludes vowels (A, E, I, O, U) and the letter Y, and zero shall not be the first character. A ninth character is added and is calculated as a checksum.
### Non-ISO 4217 cryptocurrency codes
The following are examples of commonly-used but non-compliant `ISO 4217` currency codes. This, plus the inherent flux in the number of digital currencies gave rise to `ISO 24165`.
Unofficial code | Digits | Currency | Notes
---------- | --- | ------------- | ---------
ADA | 6 | Ada | ADA conflicts with ISO 4217, because AD stands for Andorra.
BNB | 8 | Binance BNB | BNB conflicts with ISO 4217, because BN stands for Brunei Darussalam.
BSV | 8 | Bitcoin SV | BSV conflicts with ISO 4217, because BS stands for Bahamas.
BTC, XBT | 8 | Bitcoin | XBT conflicts with ISO 4217, because BT stands for Bhutan.
DASH | 8 | Dash | DASH is of non-standard length.
DOGE | 4 | Dogecoin | DOGE is of non-standard length.
ETH | 18| Ethereum | ETH conflicts with ISO 4217, because ET stands for Ethiopia.
LTC | 8 | Litecoin | LTC conflicts with ISO 4217, because LT stands for Lithuania.
### Installation
The package can be installed by adding `digital_token` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:digital_token, "~> 0.2.0"}
]
end
```
The docs can be found at <https://hexdocs.pm/digital_token>.
### Configuration
`DigitalToken` requires that a JSON library be configuration that provides a `decode!/1` function. Common libraries sucn as [poison](https://hex.pm/packages/poison), [jason](https://hex.pm/packages/jason) and [jsonrs](https://hex.pm/packages/jsonrs) are good examples.
A JSON library can be configured on `config.exs` like this:
```elixir
config :digital_token,
json_library: Jason
```
Note that the configuration parameter is the module upon which the `decode!/1` function is available.
If no configuration is set, `DigitalToken` will attempt to use `Jason`, `Poison`, the JSON library configuration for [ecto](https://hex.pm/packages/ecto) or the JSON library configured for [Phoenix](https://hex.pm/packages/phoenix).
