element-android/docs/signup.md

# Sign up to a homeserver

This document describes the flow of registration to a homeserver. Examples come from the `matrix.org` homeserver.

*Ref*: https://matrix.org/docs/spec/client_server/latest#account-registration-and-management

<!--- TOC -->

* [Sign up flows](#sign-up-flows)
  * [First step](#first-step)
  * [Step 1: entering user name and password](#step-1:-entering-user-name-and-password)
    * [If username already exists](#if-username-already-exists)
  * [Step 2: entering email](#step-2:-entering-email)
  * [Step 2 bis: user enters an email](#step-2-bis:-user-enters-an-email)
  * [Step 3: Accepting T&C](#step-3:-accepting-t&c)
  * [Step 4: Captcha](#step-4:-captcha)
  * [Step 5: MSISDN](#step-5:-msisdn)

<!--- END -->

## Sign up flows

### First step

Client request the sign-up flows, once the homeserver is chosen by the user and its url is known (in the example it's `https://matrix.org`)

```shell script
curl -X POST --data $'{}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
}
```

We get the flows with a 401, which also means that the registration is possible on this homeserver.

```json
{
  "session": "vwehdKMtkRedactedAMwgCACZ",
  "flows": [
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.dummy"
      ]
    },
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.email.identity"
      ]
    }
  ],
  "params": {
    "m.login.recaptcha": {
      "public_key": "6LcgI54UAAAAAoREDACTEDoDdOocFpYVdjYBRe4zb"
    },
    "m.login.terms": {
      "policies": {
        "privacy_policy": {
          "version": "1.0",
          "en": {
            "name": "Terms and Conditions",
            "url": "https:\/\/matrix.org\/_matrix\/consent?v=1.0"
          }
        }
      }
    }
  }
}
```

If the registration is not possible, we get a 403

```json
{
  "errcode": "M_FORBIDDEN",
  "error": "Registration is disabled"
}
```

### Step 1: entering user name and password

The app is displaying a form to enter username and password.

```shell script
curl -X POST --data $'{"initial_device_display_name":"Mobile device","username":"alice","password": "weak_password"}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
  "initial_device_display_name": "Mobile device",
  "username": "alice",
  "password": "weak_password"
}
```

401. Note that the `session` value has changed (because we did not provide the previous value in the request body), but it's ok, we will use the new value for the next steps.

```json
{
  "session": "xptUYoREDACTEDogOWAGVnbJQ",
  "flows": [
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.dummy"
      ]
    },
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.email.identity"
      ]
    }
  ],
  "params": {
    "m.login.recaptcha": {
      "public_key": "6LcgI54UAAAAAoREDACTEDoDdOocFpYVdjYBRe4zb"
    },
    "m.login.terms": {
      "policies": {
        "privacy_policy": {
          "version": "1.0",
          "en": {
            "name": "Terms and Conditions",
            "url": "https:\/\/matrix.org\/_matrix\/consent?v=1.0"
          }
        }
      }
    }
  }
}
```

#### If username already exists

We get a 400:

```json
{
  "errcode": "M_USER_IN_USE",
  "error": "User ID already taken."
}
```

### Step 2: entering email

User is proposed to enter an email. User skips this step.

```shell script
curl -X POST --data $'{"auth":{"session":"xptUYoREDACTEDogOWAGVnbJQ","type":"m.login.dummy"}}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
  "auth": {
    "session": "xptUYoREDACTEDogOWAGVnbJQ",
    "type": "m.login.dummy"
  }
}
```

401

```json
{
  "session": "xptUYoREDACTEDogOWAGVnbJQ",
  "flows": [
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.dummy"
      ]
    },
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.email.identity"
      ]
    }
  ],
  "params": {
    "m.login.recaptcha": {
      "public_key": "6LcgI54UAAAAAoREDACTEDoDdOocFpYVdjYBRe4zb"
    },
    "m.login.terms": {
      "policies": {
        "privacy_policy": {
          "version": "1.0",
          "en": {
            "name": "Terms and Conditions",
            "url": "https:\/\/matrix.org\/_matrix\/consent?v=1.0"
          }
        }
      }
    }
  },
  "completed": [
    "m.login.dummy"
  ]
}
```

### Step 2 bis: user enters an email

We request a token to the homeserver. The `client_secret` is generated by the application

```shell script
curl -X POST --data $'{"client_secret":"53e679ea-oRED-ACTED-92b8-3012c49c6cfa","email":"alice@email-provider.org","send_attempt":0}' 'https://matrix.org/_matrix/client/r0/register/email/requestToken'
```

```json
{
  "client_secret": "53e679ea-oRED-ACTED-92b8-3012c49c6cfa",
  "email": "alice@email-provider.org",
  "send_attempt": 0
}
```

200

```json
{
  "sid": "qlBCREDACTEDEtgxD"
}
```

And

```shell script
curl -X POST --data $'{"auth":{"threepid_creds":{"client_secret":"53e679ea-oRED-ACTED-92b8-3012c49c6cfa","sid":"qlBCREDACTEDEtgxD"},"session":"xptUYoREDACTEDogOWAGVnbJQ","type":"m.login.email.identity"}}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
  "auth": {
    "threepid_creds": {
      "client_secret": "53e679ea-oRED-ACTED-92b8-3012c49c6cfa",
      "sid": "qlBCREDACTEDEtgxD"
    },
    "session": "xptUYoREDACTEDogOWAGVnbJQ",
    "type": "m.login.email.identity"
  }
}
```

We get 401 since the email is not validated yet:

```json
{
  "errcode": "M_UNAUTHORIZED",
  "error": ""
}
```

The app is now polling on 

```shell script
curl -X POST --data $'{"auth":{"threepid_creds":{"client_secret":"53e679ea-oRED-ACTED-92b8-3012c49c6cfa","sid":"qlBCREDACTEDEtgxD"},"session":"xptUYoREDACTEDogOWAGVnbJQ","type":"m.login.email.identity"}}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
  "auth": {
    "threepid_creds": {
      "client_secret": "53e679ea-oRED-ACTED-92b8-3012c49c6cfa",
      "sid": "qlBCREDACTEDEtgxD"
    },
    "session": "xptUYoREDACTEDogOWAGVnbJQ",
    "type": "m.login.email.identity"
  }
}
```

User clicks on the link received by email `https://matrix.org/_matrix/client/unstable/registration/email/submit_token?token=vtQjQIZfwdoREDACTEDozrmKYSWlCXsJ&client_secret=53e679ea-oRED-ACTED-92b8-3012c49c6cfa&sid=qlBCREDACTEDEtgxD` which contains:
- A `token` vtQjQIZfwdoREDACTEDozrmKYSWlCXsJ
- The `client_secret`: 53e679ea-oRED-ACTED-92b8-3012c49c6cfa
- A `sid`: qlBCREDACTEDEtgxD

Once the link is clicked, the registration request (polling) returns a 401 with the following content:

```json
{
  "session": "xptUYoREDACTEDogOWAGVnbJQ",
  "flows": [
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.dummy"
      ]
    },
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.email.identity"
      ]
    }
  ],
  "params": {
    "m.login.recaptcha": {
      "public_key": "6LcgI54UAAAAAoREDACTEDoDdOocFpYVdjYBRe4zb"
    },
    "m.login.terms": {
      "policies": {
        "privacy_policy": {
          "version": "1.0",
          "en": {
            "name": "Terms and Conditions",
            "url": "https:\/\/matrix.org\/_matrix\/consent?v=1.0"
          }
        }
      }
    }
  },
  "completed": [
    "m.login.email.identity"
  ]
}
```

### Step 3: Accepting T&C

User is proposed to accept T&C and he accepts them

```shell script
curl -X POST --data $'{"auth":{"session":"xptUYoREDACTEDogOWAGVnbJQ","type":"m.login.terms"}}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
  "auth": {
    "session": "xptUYoREDACTEDogOWAGVnbJQ",
    "type": "m.login.terms"
  }
}
```

401

```json
{
  "session": "xptUYoREDACTEDogOWAGVnbJQ",
  "flows": [
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.dummy"
      ]
    },
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.email.identity"
      ]
    }
  ],
  "params": {
    "m.login.recaptcha": {
      "public_key": "6LcgI54UAAAAAoREDACTEDoDdOocFpYVdjYBRe4zb"
    },
    "m.login.terms": {
      "policies": {
        "privacy_policy": {
          "version": "1.0",
          "en": {
            "name": "Terms and Conditions",
            "url": "https:\/\/matrix.org\/_matrix\/consent?v=1.0"
          }
        }
      }
    }
  },
  "completed": [
    "m.login.dummy",
    "m.login.terms"
  ]
}
```

### Step 4: Captcha

User is proposed to prove he is not a robot and he does it:

```shell script
curl -X POST --data $'{"auth":{"response":"03AOLTBLSiGS9GhFDpAMblJ2nlXOmHXqAYJ5OvHCPUjiVLBef3k9snOYI_BDC32-t4D2jv-tpvkaiEI_uloobFd9RUTPpJ7con2hMddbKjSCYqXqcUQFhzhbcX6kw8uBnh2sbwBe80_ihrHGXEoACXQkL0ki1Q0uEtOeW20YBRjbNABsZPpLNZhGIWC0QVXnQ4FouAtZrl3gOAiyM-oG3cgP6M9pcANIAC_7T2P2amAHbtsTlSR9CsazNyS-rtDR9b5MywdtnWN9Aw8fTJb8cXQk_j7nvugMxzofPjSOrPKcr8h5OqPlpUCyxxnFtag6cuaPSUwh43D2L0E-ZX7djzaY2Yh_U2n6HegFNPOQ22CJmfrKwDlodmAfMPvAXyq77n3HpoREDACTEDo3830RHF4BfkGXUaZjctgg-A1mvC17hmQmQpkG7IhDqyw0onU-0vF_-ehCjq_CcQEDpS_O3uiHJaG5xGf-0rhLm57v_wA3deugbsZuO4uTuxZZycN_mKxZ97jlDVBetl9hc_5REPbhcT1w3uzTCSx7Q","session":"xptUYoREDACTEDogOWAGVnbJQ","type":"m.login.recaptcha"}}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
  "auth": {
    "response": "03AOLTBLSiGS9GhFDpAMblJ2nlXOmHXqAYJ5OvHCPUjiVLBef3k9snOYI_BDC32-t4D2jv-tpvkaiEI_uloobFd9RUTPpJ7con2hMddbKjSCYqXqcUQFhzhbcX6kw8uBnh2sbwBe80_ihrHGXEoACXQkL0ki1Q0uEtOeW20YBRjbNABsZPpLNZhGIWC0QVXnQ4FouAtZrl3gOAiyM-oG3cgP6M9pcANIAC_7T2P2amAHbtsTlSR9CsazNyS-rtDR9b5MywdtnWN9Aw8fTJb8cXQk_j7nvugMxzofPjSOrPKcr8h5OqPlpUCyxxnFtag6cuaPSUwh43D2L0E-ZX7djzaY2Yh_U2n6HegFNPOQ22CJmfrKwDlodmAfMPvAXyq77n3HpoREDACTEDo3830RHF4BfkGXUaZjctgg-A1mvC17hmQmQpkG7IhDqyw0onU-0vF_-ehCjq_CcQEDpS_O3uiHJaG5xGf-0rhLm57v_wA3deugbsZuO4uTuxZZycN_mKxZ97jlDVBetl9hc_5REPbhcT1w3uzTCSx7Q",
    "session": "xptUYoREDACTEDogOWAGVnbJQ",
    "type": "m.login.recaptcha"
  }
}
```

200

```json
{
  "user_id": "@alice:matrix.org",
  "home_server": "matrix.org",
  "access_token": "MDAxOGxvY2F0aW9uIG1hdHJpeC5vcmcKMoREDACTEDo50aWZpZXIga2V5CjAwMTBjaWQgZ2VuID0gMQowMDI5Y2lkIHVzZXJfaWQgPSBAYmVub2l0eHh4eDptYXRoREDACTEDoCjAwMTZjaWQgdHlwZSA9IGFjY2VzcwowMDIxY2lkIG5vbmNlID0gNHVSVm00aVFDaWlKdoREDACTEDoJmc2lnbmF0dXJlIOmHnTLRfxiPjhrWhS-dThUX-qAzZktfRThzH1YyAsxaCg",
  "device_id": "FLBAREDAJZ"
}
```

The account is created!

### Step 5: MSISDN

Some homeservers may require the user to enter MSISDN.

On matrix.org, it's not required, and not even optional, but it's still possible for the app to add a MSISDN during the registration.

The user enters a phone number and selects a country, the `client_secret` is generated by the application

```shell script
curl -X POST --data $'{"client_secret":"d3e285f6-972a-496c-9a22-7915a2db57c7","send_attempt":1,"country":"FR","phone_number":"+33611223344"}'  'https://matrix.org/_matrix/client/r0/register/msisdn/requestToken'
```

```json
{
  "client_secret": "d3e285f6-972a-496c-9a22-7915a2db57c7",
  "send_attempt": 1,
  "country": "FR",
  "phone_number": "+33611223344"
}
```

If the msisdn is already associated to another account, you will received an error:

```json
{
  "errcode": "M_THREEPID_IN_USE",
  "error": "Phone number is already in use"
}
```

If it is not the case, the homeserver send the SMS and returns some data, especially a `sid` and a `submit_url`:

```json
{
  "msisdn": "33611223344",
  "intl_fmt": "+336 11 22 33 44",
  "success": true,
  "sid": "1678881798",
  "submit_url": "https:\/\/matrix.org\/_matrix\/client\/unstable\/add_threepid\/msisdn\/submit_token"
}
```

When we execute the register request, with the received `sid`, we get an error since the MSISDN is not validated yet:

```shell script
curl -X POST --data $'{"auth":{"type":"m.login.msisdn","session":"xptUYoREDACTEDogOWAGVnbJQ","threepid_creds":{"client_secret":"d3e285f6-972a-496c-9a22-7915a2db57c7","sid":"1678881798"}}}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
  "auth": {
    "type": "m.login.msisdn",
    "session": "xptUYoREDACTEDogOWAGVnbJQ",
    "threepid_creds": {
      "client_secret": "d3e285f6-972a-496c-9a22-7915a2db57c7",
      "sid": "1678881798"
    }
  }
}
```

There is an issue on Synapse, which return a 401, it sends too much data along with the classical MatrixError fields:

```json
{
  "session": "xptUYoREDACTEDogOWAGVnbJQ",
  "flows": [
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.dummy"
      ]
    },
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.email.identity"
      ]
    }
  ],
  "params": {
    "m.login.recaptcha": {
      "public_key": "6LcgI54UAAAAABGdGmruw6DdOocFpYVdjYBRe4zb"
    },
    "m.login.terms": {
      "policies": {
        "privacy_policy": {
          "version": "1.0",
          "en": {
            "name": "Terms and Conditions",
            "url": "https:\/\/matrix.org\/_matrix\/consent?v=1.0"
          }
        }
      }
    }
  },
  "completed": [],
  "error": "",
  "errcode": "M_UNAUTHORIZED"
}
```

The user receive the SMS, he can enter the SMS code in the app, which is sent using the "submit_url" received ie the response of the `requestToken` request:

```shell script
curl -X POST --data $'{"client_secret":"d3e285f6-972a-496c-9a22-7915a2db57c7","sid":"1678881798","token":"123456"}' 'https://matrix.org/_matrix/client/unstable/add_threepid/msisdn/submit_token'
```

```json
{
  "client_secret": "d3e285f6-972a-496c-9a22-7915a2db57c7",
  "sid": "1678881798",
  "token": "123456"
}
```

If the code is not correct, we get a 200 with:

```json
{
  "success": false
}
```

And if the code is correct we get a 200 with:

```json
{
  "success": true
}
```

We can now execute the registration request, to the homeserver

```shell script
curl -X POST --data $'{"auth":{"type":"m.login.msisdn","session":"xptUYoREDACTEDogOWAGVnbJQ","threepid_creds":{"client_secret":"d3e285f6-972a-496c-9a22-7915a2db57c7","sid":"1678881798"}}}' 'https://matrix.org/_matrix/client/r0/register'
```

```json
{
  "auth": {
    "type": "m.login.msisdn",
    "session": "xptUYoREDACTEDogOWAGVnbJQ",
    "threepid_creds": {
      "client_secret": "d3e285f6-972a-496c-9a22-7915a2db57c7",
      "sid": "1678881798"
    }
  }
}
```

Now the homeserver considers that the `m.login.msisdn` step is completed (401):

```json
{
  "session": "xptUYoREDACTEDogOWAGVnbJQ",
  "flows": [
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.dummy"
      ]
    },
    {
      "stages": [
        "m.login.recaptcha",
        "m.login.terms",
        "m.login.email.identity"
      ]
    }
  ],
  "params": {
    "m.login.recaptcha": {
      "public_key": "6LcgI54UAAAAABGdGmruw6DdOocFpYVdjYBRe4zb"
    },
    "m.login.terms": {
      "policies": {
        "privacy_policy": {
          "version": "1.0",
          "en": {
            "name": "Terms and Conditions",
            "url": "https:\/\/matrix.org\/_matrix\/consent?v=1.0"
          }
        }
      }
    }
  },
  "completed": [
    "m.login.msisdn"
  ]
}
```