Private Blockchain Notary Service

About

From Udacity:

Data stored on a blockchain can vary from digital assets (e.g. documents, media) to copyrights and patent ownership. These pieces of data need to be reliably secured, and we require a way to prove they exist — this is where signing and validation are key. In this project you will build a private blockchain notary service to validate and provide proof of existence for your favorite star in the universe.

Supporting courses:

• Blockchain Web Services

Notes

This project uses express to provide an API to register stars in the universe. To register a star, a user must first prove ownership of a wallet address by going through a timed handshake with the server using:

1. The /requestValidation endpoint to initiate validation. This endpoint provides the user with a message to sign and a validation window to complete the validation process within (default: 5 minutes).
2. The /message-signature/validate endpoint to complete validation by providing the signed message within the 5 minute window. See test/generate-signature.js to sign a message manually for testing purposes.

Once validated, a user can then register a star using the /block endpoint. The API also contains endpoints for searching by block hash (/hash:[HASH]), block address (/address:[ADDRESS]), and block height (/[HEIGHT]). See the endpoints section below for more details.

Please note that this project is for learning purposes only, and there is no attempt made to validate star data beyond simply ensuring the required data is present (See here). In the event this was a public facing API, a custom or third-party library would be needed to validate star data before registration. Also, the endpoint names were provided (and required) by Udacity.

Endpoints

Request Validation - initiates a request for validation

• URL: /requestValidation
• Method: POST
• Required Parameters
  • { "address:" "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31" }
• Success Response
  • Code: 200
  • Example Content:

  {
    "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
    "requestTimestamp": "1539024605",
    "message": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31:1539024605:starRegistry",
    "validationWindow": 300
  }

• Error Response
  • Codes: 500
  • Example Content: { "error:" true, message: "Something bad happened ಥ_ಥ" }

Validate Signature - validates a signed message within a validation window

• URL: /message-signature/validate
• Method: POST
• Required Parameters

  {
    "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
    "signature": "IKZesuHUGrFWq6btamgHz4Si/2SUIGGRcvtSMVQd42lrIjaHQog4bFI5JuHetYZflWW5BzHCnJNSVzFU5mXmS5Q="
  }

• Success Response
  • Code: 200
  • Example Content:

  {
    "registerStar": false,
    "status": {
        "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
        "requestTimestamp": 1539023844,
        "message": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31:1539023844:starRegistry",
        "validationWindow": 291,
        "messageSignature": "invalid"
    }
  }
  

• Error Response
  • Codes: 400, 403, 500
  • Example Content: { "error:" true, message: "Something bad happened ಥ_ಥ" }

Register Star - registers a new star in the blockchain containing specified data

• URL: /block
• Method: POST
• Required Parameters

  {
    "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
    "star": {
      "dec": "-26° 29' 24.9",
      "ra": "16h 29m 1.0s",
      "story": "Found star using https://www.google.com/sky/"
    }
  }

• Success Response
  • Code: 201
  • Example Content:

  {
    "body": {
        "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
        "star": 
        "dec": "-26° 29' 24.9"
            "ra": "16h 29m 1.0s",
            "story": "466f756e642073746172207573696e672068747470733a2f2f7777772e676f6f676c652e636f6d2f736b792f"
        }
    }
    "height": 1,
    "previousBlockHash": "cf0d39b631ecfde41feb7599ef06fbbffe47197eaff949547698d8ef04af9b6d",
    "time": "1539024653"
    "hash": "93b81914d53bf079c31923851b17108506c19160f208f9d0a463420a37ce8acf"
  }

• Error Response
  • Codes: 400, 403, 500
  • Example Content: { "error:" true, message: "Something bad happened ಥ_ಥ" }

Lookup Star (Address) - lookup star by wallet address

• URL: stars/address:[ADDRESS]
• Method: GET
• Required Parameters
  • ADDRESS=[string]
• Success Response
  • Code: 200
  • Example Content

  [
    {
        "body": {
            "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
            "star": {
                "dec": "-26 29 24.9",
                "ra": "16h 29m 1.0s",
                "story": "466f756e642073746172207573696e672068747470733a2f2f7777772e676f6f676c652e636f6d2f736b792f",
                "decodedStory": "Found star using https://www.google.com/sky/",
            }
        },
        "height": 1,
        "previousBlockHash": "2736058a41afbb4c36ed579ec80ba52399a348603cd1d01f4cf26db03ff7186c",
        "time": "1538942458",
        "hash": "40c5a1115dcd6e7733271a50d9a167d80ea541af4cf349e9dcfcec1518d5cad7"
    },
    ...
  ]

• Error Response
  • Codes: 500
  • Example Content: { "error": true, message: "Something bad happened ಥ_ಥ" }

Lookup Star (Hash) - lookup a star by its block hash

• URL: stars/hash:[HASH]
• Method: GET
• Required Parameters
  • HASH=[string]
• Success Response
  • Code: 200
  • Example Content

  {
    "body": {
        "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
        "star": {
            "dec": "-26° 29' 24.9",
            "ra": "16h 29m 1.0s",
            "story": "47656E6573697320426C6F636B",
            "decodedStory": "Genesis Block"
        }
    },
    "height": 0,
    "previousBlockHash": "",
    "time": "1539023948",
    "hash": "cf0d39b631ecfde41feb7599ef06fbbffe47197eaff949547698d8ef04af9b6d"
  }

• Error Response
  • Codes: 500
  • Example Content: { "error": true, message: "Something bad happened ಥ_ಥ" }

Lookup Star (Height) - look up a star in the blockchain for a specified height

• URL: /block/[HEIGHT]
• Method: GET
• Required Parameters
  • HEIGHT=[integer]
• Success Response
  • Code: 200
  • Example Content

  {
    "body": {
        "address": "19AAjaTUbRjQCMuVczepkoPswiZRhjtg31",
        "star": {
            "dec": "-26° 29' 24.9",
            "ra": "16h 29m 1.0s",
            "story": "47656E6573697320426C6F636B",
            "decodedStory": "Genesis Block"
        }
    },
    "height": 0,
    "previousBlockHash": "",
    "time": "1539023948",
    "hash": "cf0d39b631ecfde41feb7599ef06fbbffe47197eaff949547698d8ef04af9b6d"
  }

• Error Response
  • Codes: 400, 500
  • Example Content: { "error": true, message: "Something bad happened ಥ_ಥ" }

Requirements

• Node
• Node Package Manager (npm)

Install & Run

1. npm install
2. npm start

Code Quality

This codebase adheres to the Airbnb JavaScript/React/JSX Style Guide

Code Organization (src)

├── app.js
├── controllers
│   ├── index.js
│   ├── routes.js
│   └── stars.js
├── helpers
│   └── index.js
├── middlewares
│   └── index.js
└── models
    ├── block.js
    ├── blockchain.js
    ├── blockchainData.js
    └── starRequestData.js

4 directories, 10 files

Grading (by Udacity)

Criteria	Highest Grade Possible	Grade Recieved
Blockchain ID Validation Routine	Meets Specifications	Meets Specifications
Star Registration Endpoint	Meets Specifications	Meets Specifications
Star Lookup	Meets Specifications	Meets Specifications