Support vault format 8

[SailReal]

Summary

Starting with Cryptomator 1.6.0 the user should be able to open and create vaults in the new vault format 8.

Additional Context

Add Vault

Listing of the folder, if vault.cryptomator and masterkey.cryptomator found, hide masterkey.cryptomator.

Unlock Vault

1. No listing, directly read vault.cryptomator, if not found, read masterkey.cryptomator
2. If vault.cryptomator exists, check scheme
3. If masterkeyfile scheme, load masterkey.cryptomator and verify the JWT using the masterkey.
4. Read vault version and further parameters like maxFilenameLen to initialize and configure the correct CryptoDecorator.

While starting the unlock, display a generic progress dialog. As soon as the vault.cryptomator is found and the masterkeyfile scheme is recognized, switch to the EnterPasswordDialog. The same applies when no vault.cryptomator file found but a masterkey.cryptomator for legacy vaults.

Format

vault.cryptomator : which is a JWT, e.g.
eyJraWQiOiJtYXN0ZXJrZXlmaWxlOm1hc3RlcmtleS5jcnlwdG9tYXRvciIsInR5cCI6IkpXVCIsImFsZyI6IkhTMjU2In0.eyJtYXhGaWxlbmFtZUxlbiI6MjIwLCJmb3JtYXQiOjgsImp0aSI6IjhmNzhkNTIwLTNiYzMtNDQ3NS04ZDlmLTM0OWRlZjg3Yzk4OCIsImNpcGhlckNvbWJvIjoiU0lWX0NUUk1BQyJ9.BRAq_FN-ahAh6iy8jY32r0ZRfPlIDy-UzOoRL6xHPUk

HEADER
{
  "kid": "masterkeyfile:masterkey.cryptomator",
  "typ": "JWT",
  "alg": "HS256"
}

PAYLOAD
{
  "maxFilenameLen": 220,
  "format": 8,
  "jti": "8f78d520-3bc3-4475-8d9f-349def87c988",
  "cipherCombo": "SIV_CTRMAC"
}

masterkey.cryptomator

{
  "version": 999,
  "scryptSalt": "34HorXsZLss=",
  "scryptCostParam": 32768,
  "scryptBlockSize": 8,
  "primaryMasterKey": "KDywJdKFqSVtABXiqtqPkkZ8zH5dhBkNQBhJSnU/JpPr7fCE6GPPEw==",
  "hmacMasterKey": "PqHtidj8g011TMNZXugWXRTqM7P24e+j2zHkpWFuRA7yGDUOLo9iuw==",
  "versionMac": "WPxqVFYsjXcUuXPGCpaovUh0ZGgyxUc8TOns8t7evPA="
}

See cryptomator/cryptofs#95 for more details.