Sending textcoins

Textcoin is a payment sent though email or other text based media, such as chat apps (Telegram, Whatsapp, WeChat, etc). See https://medium.com/byteball/sending-cryptocurrency-to-email-5c9bce22b8a9. Textcoins can also be printed on paper, scratch cards, or PIN envelopes and passed on like paper wallets.

Sending textcoins from server-side (headless) wallets is easy: you use the same functions you normally use to send to Byteball addresses but instead of the recipient's Byteball address you write:

• textcoin:userEmailAddress for sending to email, or
• textcoin:someUniqueIdentifierOtherThanEmail for sending via any other text based media

Examples: textcoin:pandanation@wwfus.org or textcoin:ASDFGHJKL.

Sample code:

var headlessWallet = require('headless-byteball');

let opts = {
	asset: null, 
	amount: 1000, // bytes
	to_address: "textcoin:pandanation@wwfus.org",
	email_subject: "Payment in textcoin"
};

headlessWallet.issueChangeAddressAndSendMultiPayment(opts, (err, unit, assocMnemonics) => {
	....
});

The opts object has an optional field email_subject which is the subject of the email sent to the user. To send emails, you need to set the following fields in your configuration files:

• from_email: the address your emails are sent from. Must be on your domain, otherwise the emails are likely to be non-delivered or labeled as spam
• smtpTransport: type of SMTP transport used to deliver emails:
  • local: (this is the default) use /usr/sbin/sendmail
  • direct: connect directly to the recipient's MX server, this minimizes the number of intermediaries who are able to see and potentially steal the textcoin, but this method is not reliable as there are no retries
  • relay: send through a relay server. In this case, you need to also set its host name in smtpRelay. If it requires authentication, you need to also set smtpUser and smtpPassword.

The callback of issueChangeAddressAndSendMultiPayment and all similar functions has an optional 3rd parameter assocMnemonics which is an associative array of all generated textcoins (BIP39 mnemonics) indexed by the address from the input parameters.

{
	"textcoin:pandanation@wwfus.org": "barely-album-remove-version-endorse-vocal-weasel-kitten-when-fit-elbow-crop"
}

All the keys of the array have a textcoin: prefix, like in input parameters.

If you are sending though any media other than email, you use assocMnemonics to find mnemonics generated for each output address (in the example above, you would find it by the key textcoin:ASDFGHJKL) and then deliver them yourself.

For example, if you are writing a Telegram bot that rewards users for certain actions, you create a clickable link by prefixing the mnemonic with https://byteball.org/#textcoin?:

https://byteball.org/#textcoin?barely-album-remove-version-endorse-vocal-weasel-kitten-when-fit-elbow-crop

and send it in chat.

If you are going to print a paper wallet from an ATM, you just print the mnemonic and optionally encode it in a QR code.

Example code in a Telegram bot that sends users textcoins for passing a quiz: https://github.com/byteball/telegram-quiz/blob/master/src/wallet.js

Example code that creates a list of textcoins for subsequent mass sending (e.g. via MailChimp): https://github.com/byteball/headless-byteball/blob/master/play/create_textcoins_list.js