JakeUrban

## SEP-10 3.0

### TL;DR

Implement the changes described in the [SEP-10 v3.0 PR](https://github.com/stellar/stellar-protocol/pull/746) by November 13th. It adds a check for the correct `homeDomain` value in the SEP-10 challenge transaction. `homeDomain` is the domain hosting the [SEP-1 stellar.toml](sep-0001.md) containing a `WEB_AUTH_ENDPOINT` and `SIGNING_KEY`.

The SEP-10 v3.0 PR is not merged, but the only changes still in discussion relate to phrasing. No more functional changes will be introduced.

### Background & Description

JakeUrban

**This gist is an example, and the content should not be taken to be up-to-date.

The following [changes](https://github.com/stellar/stellar-protocol/commit/28c636b4ef5074ca0c3d46bbe9bf0f3f38095233#diff-72480d0894ae2d1a31c229b64ad4c37b) were recently merged to [SEP-10](https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0010.md):

- [ ] the Manage Data operation's key includes a `homeDomain` [FQDN](https://en.wikipedia.org/wiki/Fully_qualified_domain_name) instead of the `anchorName` string
- [ ] a `SIGNING_KEY` attribute in the [stellar.toml](https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0001.md) of the service implementing SEP-10 is required
- [ ] client applications _must_ match the value of the Manage Data operation's key with the home domain used in the request for the service's TOML file
- [ ] client applications _must_ verify that the service's `SIGNING_KEY` keypair was used to sign the challenge transaction

Each SDK must update to enable the _first_ and ideal