# Cryptocurrency Wallet as A Service

A unified interface acted as wallets for customers to interact with cryptocurrency blockchains.

[TOC]

## Api Document

https://tinyurl.com/raha7sa4

## Attributes

1. Secure: Properly generate/store/encrypt/decrypt private keys.
2. Multi-currency supported: Bitcoin / Ether / Tron / Tether (Erc20) / Tether (Trc20)
3. Fast and Stable:
* an good average response time for every APIs.
* an acceptable process time for blockchain transactions.

## Components

For each client *account*, each *cryptocurrency*, the client has their own:

* Balance (for checking the balance of the money)
* Addresses (for receiving money)
* Deposits (for checking the history of deposits)
* Withdrawals (for checking the history of withdrawals, transactions fees, ...)
* ...

## Capabilities

In terms of Http methods:

| | read | create | update | |
| -------- | ------| ------ | ------ | --------- |
| Balances | GET | | | |
| Addresses | GET | POST | PATCH | |
| Deposits | GET | POST | | Notifications |
| Withdrawals | GET | POST | | Notifications |
| ... | ... | ... | ... | ... |

1. As an user I can create as many *addresses* as I want to receive bitcoins.
2. As an user I can create an *address* with a prescribed *web-hook* (url) so that I will be notified when the address has received a new deposit.
3. As an user I will be notified when there comes into a new *deposit*.
4. As an user I can check out my balance for my bitcoins.
5. As an user I can withdrawal my bitcoins, and latter be notified when the transaction is confirmed.

## Developer Guide

* Ensuring Uniqueness of Withdrawals:
Each request is created by client-side, and the server(api) and the client must ensure uniqueness of every request under the possible network failures. (via e.g. `client_id`)
* Ensuring Account Separation:
Prevent an client from withdrawal more money than their balances.
* Ensuring Rejection of Potential Fake Deposits for a Cryptocurrency:
* For example: **Ripple Partial Payment Exploit** - https://xrpl.org/partial-payments.html#partial-payments-exploit
* Ensuring Never Exposing Private Keys to Networks.
* About Tests:
* Unit Tests (Automated)
* Integration Tests (Automated)
* Scenario Tests on Testnet environment (Manual)
* Scenario Tests on Mainnet environment (Manual)
* Languages, Frameworks, Deployment ...:
* TypeScript/Node14
* JavaScript/Node14
* MongoDB
* Jest
* Drone CI
* Docker
* GCP with Cloud Key Management, Secret Manager, Load Balancer