Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
114 lines (60 sloc) 11.5 KB

Identity

Although overhide enables pseudonimity, it absolutely requires the concept of "identity".

Identity is necessary for authorization to brokers and preventing abuse. Brokers do not want to know who's using them: what service and which user. But they do need to authorize and possibly get paid for services provided. To the broker, there is nothing dictating it'll be used for a specific purpose. A broker might be brought online to support a specific use, but there's nothing preventing anyone from using it for something completely unrelated. But it doesn't matter at the end of the day: as long as the broker is reimbursed, there is no concept of abuse.

Leveraging ledgers for remuneration is key to this reimbursement mechanism.

Desired Qualities for Identity

It shouldn't be immediately evident which data belongs to which ledger address.

We want the ability to have a public ledger address prove it has transacted with the broker's public ledger address in such a way that the authorized datastore storage is not traceable to the subscriber.

It'll always be publicly known that a pseudonym subscribes to the broker: broker's public ledger address is well known and advertised and the pseudonym's transaction is in the public ledger. What's inhibited is tracability of which data is tied to the pseudonym.

Identity Tracked by Broker

An identity represents a user, a group, or a service provider.

The broker datastore keeps a mapping of each datastore-key to an owning identity.

Additionally, the broker datastore keeps a mapping of each user-address to an identity'.

Both identity and identity' are functions of some user provided secret, secret-phrase. identity cannot be correlated to identity' without at least knowing this secret-phrase.

Tracking datastore-keys by identity allows to prove data ownership.

Tracking user-address by identity' ensures only a single secret-phrase is used for a given user-address within the system. This prevents abuse of the broker: prevents a user from using multiple secret-phrases for a single user-address to double-dip on any paid-for subscriptions.

Specifically:

  • identity := user-addresshash(secret-phrase) // hash of secret-phrase salted with user-address
  • identity' := broker-salthash(secret-phrase) // hash of secret-phrase salted with some overhide broker specific salt
  • datastore-key maps to identity
  • user-address maps to identity'

Identity Authority

Being authenticated as an "active" identity within an overhide broker system means ability to create new datastore-keys with identity as owner, ability to write to such keys, and ability to read any datastore-key in the whole system.

Only "active" identities are authorized. An "active" identity is an identity with an active subscription.

Specific read/write usage rates and limits to an overhide broker system are also authorized per "active" identity:

  • read rate (bytes/second)
  • write rate (bytes/second)
  • storage limit (bytes)

Identity Authentication

A user authenticates in order to establish their identity for a session with an overhide broker.

An identity is a user-addresshash(secret-phrase) such that F(secret-phrase, user-address, user-addresssig(secret-phrase)) returns 'true' where secret-phrase, user-address, and user-addresssig(secret-phrase) are provided by the authenticated user. F(..) returns 'true' if secret-phrase checks out against user-addresssig(secret-phrase).

user-address is the public address of a user: likely a ledger public-key. To prove that the user owns the provided user-address, the user signs the secret-phrase with user-addresspriv: the corresponding ledger private-key.

The secret-phrase is something only the authenticated user is privy to. The overhide broker hashes it to create an identity. In the future to prove one's identity the user must know the secret-phrase such that it hashes to the identity, proving the user knows the secret-phrase corresponding to said identity.

During authentication the broker system also verifies that there is a single mapping from the provided user-address and secret-phrase to a broker-salthash(secret-phrase). If the mapping exists and the computed hash doesn't equal the stored hash, the provided secret-phrase is different from one provided earlier. As such the user-address already has an identity in the system with a different secret-phrase, and the secret-phrase provided cannot be accepted.

If the user remembers the previous secret-phrase, the user's original identity can be calculated and all datastore-keys owned by that identity can be changed to be owned by an identity with a new secret-phrase: somewhat akin to a password change. The user-address could be changed as part of this operation as well.

If the user doesn't remember the previous secret-phrase, the original identity cannot be calculated, all datastore-keys owned by that identity are unrecoverable.

Authenticated Sessions

When an identity authenticates a token is returned to the client software. This token is valid for some time and can be used by the client to access overhide APIs.

If the token expires, client software must re-authenticate the identity.

The overhide broker keeps an in-memory whitelist of valid tokens. The broker doesn't keep track of mappings between tokens and identities or tokens and user-addresses. But the token itself--exchanged between broker and client software--contains the identity and a hashed version of the user-address. The hashing approach for the user-address hash is broker specific, but could likely be broker-salthash(user-address). The token contains sufficient internal checks (hashes) to ensure the whitelisted token is unmodifiable.

Providing a whitelisted token to overhide APIs allows them to validate ownership and write/post rights at access time.

Subscriptions

Subscriptions are either gratis or paid-for (time-bound) authorizations to use. A subscription amount is a tally of all transactions between a subscriber and a broker (or service) on a supported ledger within a time period: it could be an amount within the last several hours or at least one free transaction at any point in time in history.

Overhide isn't concerned with the exact mechanism for subscriptions and recurring subscriptions outside of what's made available with an implementation of the remuneration API. There is no overhide specific token. Implementations of the renumeration API abstract different ledgers for subscription purposes.

At a minimum a transaction could take place from a user-address to broker-address and a simple transaction timestamp check is all that can be done to set subscription expiration dates. The remuneration API abstracting said ledger would make this information available to the overhide broker. The user-address--being a ledger address--is used by the overhide broker to check a user's subscription and authorities: access levels to the broker system. If the transaction shows sufficient fees paid (if any) sufficiently recently (could be eons), the user is subscribed.

More capable ledger implementations could have more advanced smart contracts that make funds available at specific dates (subscription renewal). Again, these mechanisms and complexities are hidden behind the specific remuneration API.

Regardless of the technology behind a remuneration API, the API is there to tell the overhide broker if an identity is "active" and at what levels.

A subscribed user is a user with an "active" identity. The "active" state of an identity is checked explicitly on authentication. An overhide broker tracks two expiration dates for each identity:

  1. the active-until date: date the identity subscription expires.
  2. the available-until date: date after which the overhide broker may delete all data owned by identity.

active-until may be same or earlier than available-until date.

active-until and available-until will be updated on authentication as per the most recent ledger transaction from user-address to broker-address.

secret-phrase Security

Note that the overhide broker is privy to the user's secret-phrase during runtime (not a secret-key for a user-address). As such it's possible the overhide broker can be used to expose users' secret-phrases such that users' data can be deleted or corrupted: the data cannot be deciphered as the datastore-value is (usually) encrypted by secrets known only to the users themselves. Therefore the overhide broker must be trusted to not give up users' secret-phrases as they're passed in. In reality if an overhide broker implementation cannot be trusted in this situation, it likely cannot be trusted with it's underlying data storage either. Such breaches of trust would damage an overhide broker's reputation because of the data-loss.

Similarly, an overhide broker has no reason to expose identities. These should always be internal to the broker system.

By the same token always ensure the overhide broker being accessed has valid and verified SSL certificates.

Two Address Authentication: Authorize use of Service

The above "Subscriptions" section describes how an overhide broker can verify validity of a user's subscription to use the broker.

The same mechanism of looking up transactions from user-address to broker-address can be used to validate transactions to other public addresses, for example from the user-address to a service-address.

Refer to the broker API to this end.

This is just a utility mechanism and doesn't tie into the identity and its active-until or available-until metadata.

You can’t perform that action at this time.