Background on the mechanics of the ether pre-sale

Throughout the run-up to the ether sale we can be releasing a sequence of weblog posts concerning our growth plans and supposed organizational construction. At this time we describe some of the background particulars of the ether sale module.  The sale module can be displayed on our web site at for the period of the sale.

What’s it?

The ether sale is an HTML/JavaScript internet utility that allows individuals and organizations to pre-purchase ether tokens with bitcoin. Ether could also be bought by events excited about utilizing it of their growth of distributed purposes on the Ethereum platform or just to pay for the use of purposes on the platform as soon as the genesis block is launched.  The applying runs principally inside the browser, together with pseudo random quantity era (PRNG) and encryption/decryption of consumer secrets and techniques.

Moreover, we can be making accessible a standalone pure Python utility that can be utilized from a command line interface to buy ether in lieu of utilizing the web site retailer.

Web site workflow:

1. After agreeing to the retailer’s Phrases and Circumstances, the purchaser enters the desired quantity of ether to buy, their e-mail tackle, a password to make use of for encryption, and generates a “random” seed forming the foundation for his or her transaction-specific bitcoin & Ethereum addresses.
2. The consumer purchaser sends fee in bitcoin to the generated tackle which is displayed on the retailer web page and likewise supplied in a downloadable encrypted pockets file. When the browser, which is monitoring the bitcoin blockchain, sees sufficient funds have been despatched to this generated tackle, the browser creates a brand new transaction forwarding the bitcoin to the genesis sale tackle. This transaction is signed by the purchaser’s browser and submitted to the bitcoin community. No transaction information is saved on the any servers as a result of the Bitcoin blockchain serves as the buy database.
3. After the transaction has been efficiently submitted, the consumer purchaser is once more prompted to obtain a backup copy of their encrypted pockets along with being emailed one other backup file.  The client ought to be conscious that preserving the pockets as an e-mail attachment in an e-mail account for any interval of time represents a vulnerability.  The e-mail attachment ought to be downloaded to a protected pc at the earliest alternative and the e-mail ought to be expunged from the e-mail system.

(What follows is technical data, the GUI we’ve developed abstracts all of that is in a really user-friendly method)

Pockets encryption course of: 

1. Randomgen a SEED.
2. BKPKEY = sha3(SEED + “x02″)[:16]
3. KEY = pbkdf2(PW)
4. ENCSEED = encrypt(KEY, SEED)
5. WALLET = [ ENCSEED, BKPKEY ] (plus non-sensitive information like ethereum and bitcoin tackle)

The BTC and ETH privkeys and addresses are derived from the SEED.

Seed restoration course of: 

1. WALLET + PW restoration:  (regular)
2. KEY = pbkdf2(PW)
3. SEED = decrypt(KEY, ENCSEED)

Overview of web site steps for making an ether buy:

1. Purchaser clicks “Buy Ether” and agrees to the Phrases & Circumstances
2. Purchaser enters preliminary buy data
   
   1. Purchaser enters the quantity of ether they’d wish to buy
   2. Purchaser enters e-mail tackle as the vacation spot for pockets backup file
   3. Purchaser enters passphrase, which serves as an encryption seed. A really sturdy passphrase is extremely really helpful

3. Purchaser generates entropy by transferring their mouse or tapping their display. A “seed” is constructed based mostly on this generated entropy in addition to different random system inputs. When the desired entropy size is achieved the pockets is generated utilizing the seed.  The pockets accommodates:
   
   1. a person BTC tackle to ship the funds to
   2. a person ETH tackle
   3. an encrypted seed
   4. a backup encrypted seed

4. The browser sale app checks the newly created BTC tackle to see if funds arrive. Earlier than sending any funds, the purchaser has a possibility to obtain the pockets. If an issue happens between transactions, any funds ship to the purchaser’s private deposit tackle can be accessible with the passphrase. If the unspent stability of the BTC tackle > 0.01 BTC, the browser sale app generates a signed transaction from the newly created BTC tackle with 2 particular outputs:
   
   1. an output of the whole unspent stability minus miners price to the predominant sale BTC tackle–this btc tackle is the place all the funds go, it’s a hard and fast, identified BTC tackle.
   2. an output of 10000 satoshi to a BTC tackle generated from the (string) ETH tackle–this bitcoin tackle is for confirming ethereum addresses and is exclusive for each transaction.

5. The browser sale app prompts the purchaser to obtain their pockets once more & and likewise sends the purchaser an e-mail containing a backup for the ether pockets.  The identical warning as said above applies.  Don’t depart the pockets as an e-mail attachment in an e-mail system.  Obtain as quickly as potential and be certain that the e-mail is expunged.
6. The browser sale app will show the quantity of bitcoin transaction confirmations

In order that’s it! Though there’s rather a lot of technical issues taking place in the background, the GUI we’ve developed will make the course of a click on by click on operation.