Why is this information sensitive? The deeper Equifax problem

As the world now knows Equifax, the credit rating company and master of our fates, suffered a data breach in May and June 2017, which revealed to criminals details of 143 million people. (I would have liked to say, “143 million customers“, but that is very far from the case. We have no control at all over Equifax and other credit rating companies collecting information about us. We are neither their customers nor users.)

The revealed data includes:

  • Social Security numbers
  • Dates of birth
  • Addresses
  • Driver’s license numbers (unspecified number of these)
  • Credit card numbers (209,000 of these)

There are many important things to ask about this incident, but what I am focusing on today is why has non-secret information become sensitive? None of those numbers were designed to be used as secrets (including social security numbers and credit card numbers), yet we live in a world in which we have to keep these secret. What is going on here?

Identity crisis

Names only provide a first pass at identifying individuals in some list or database. There are a lot of Jeffrey Goldbergs out there. (For example, I am not the journalist and now editor-in-chief at the Atlantic. But there are lots of others that I also am not.) Also people change their names. Some people change their name when they get married. (My wife, Lívia Markóczy, decided to keep her name because we figure it is easier to spell than “Goldberg”.) Others change their names for other reasons.

We have three “Jeffreys” at AgileBits, but fortunately we have distinct family names. Though sometimes I think that everyone who joins the company should just go by “Jeffrey” to avoid confusion.

Anyway, names alone are not enough to figure out who we are talking about once we get beyond a small group of people. So we use other things. Social security numbers worked well in the US for some time. They didn’t change over your lifetime (except in rare circumstances) and nearly everyone had one. Dates of birth also don’t change. So a combination of a name, a date of birth, and a social security number was a good way to create an identifier for nearly every individual in the US, with the understanding that a name might change.

Sometimes it is not a person that we need to uniquely and reliably identify. Sometimes it is something like a bank account or charge account. Cheques (remember writing those?) have the account number printed on them. They uniquely identify the particular account within a bank, and a routing number (in the US) identifies the bank. The routing number is also printed on each cheque.

Things like social security numbers and driver’s license numbers are designed as “identifiers” of people. They are ways to know which Jeffrey Goldberg is which. Occasionally getting email meant for the journalist is no big problem, but if he gets himself on the no-fly list, I want to be sure that I don’t get caught up in that net. Likewise, I don’t want my doctor or pharmacist mixing me up with some other Jeffrey Goldberg who isn’t allergic to the same stuff that I am. Nor does some other Jeffrey Goldberg want the record of speeding tickets I seem to acquire.

Things like bank or charge account numbers are used to uniquely and reliably identify the particular account. While I wouldn’t mind if my credit card charges were charged against someone else’s account, they would certainly mind, and so would the the relevant bank. (I’m going to just start using the word “bank” broadly to include credit card issuers, automobile loan issuers, and the like.)

A username on some system is also an identifier. It identifies to the service which particular user or account is being talked about. I am jpgoldberg on our discussion forums. That username is how the system knows what permissions I have and how to verify my password.

Identifiers are bad secrets

Something that is designed and used as an identifier is hard to keep secret. A service can hash a password, but it needs to know which account is being talked about before it can look up any information. In many database systems, identifiers are used as record locators. These need to be efficiently searchable for lookup.

Identifiers also need to be communicated before secret stuff can happen. Bank account numbers are printed on cheques for a reason. Now really clever cryptographic protocols – like the one behind Zero Cash – can allow for transactions which don’t reveal the account identifier of the parties, but for almost everything else, account identifiers are not secret.

Identifiers are hard to change. If you depend on the secrecy of some identifier for your security, then you are stuck with a problem when those secrets do get compromised. It is a pain to get a new credit card number, and it is far worse trying to get a new social security number. Getting a new date of birth might also be a teeny tiny problem.
The point here is that, given what identifiers are designed to do, they aren’t designed to be kept secret.


Authentication is the process of proving some identity. And this almost always involves proving that you have access to a secret that only you should have access to. When I use 1Password to fill in my username (jpgoldberg) and password to our discussion forums, I am proving to the system that I have access to the secret (the password) associated with that particular account.

The password is designed to be kept secret. The server running the discussion forum doesn’t need to search to find the password (unlike searching to do a lookup from my username), so it can get away with storing a salted hash of the password. Also, I can change the password without losing all of the stuff that lives under my account. (Changing my username would require more work.) Plus, my username is used to identify me to other people using the system, and so is made very public. My password, on the other hand, is not.

What banks did wrong

The mess we are in today is because financial institutions have been using knowledge of identifiers as authentication secrets. The fact that someone can defraud a credit card issuer by knowing my credit card number (an account number) and my name and address (matters of public record) is all because at one point, credit card issuers decided that knowledge of the credit card number (a non-secret account number) was good way to authenticate.

I have not researched the history in detail, but I believe that this started with credit card numbers when telephone shopping first became a thing (early 1970s, I believe). Prior to then, credit cards were always used when the account holder was physically present and could show the merchant an ID with a signature. The credit card number was used solely as designed up until that point: as a record locator.

The same thing is true of social security numbers. Social security numbers were not secret until banks started to use knowledge of them as authentication proofs when they introduced telephone banking. Before then, there was nothing secret about them.

And on it goes

Because high-value systems use knowledge of identifiers as authentication proofs we are in deep doo-doo. And it will take a long time to dig ourselves out. But we continue to dig ourselves deeper.

It is fine to be asked for non-secret identifying information to help someone or something figure out who they are talking about. I like it when my doctor asks for my date of birth to make sure that they are looking at and updating the right records. But when they won’t reveal certain information to me unless I give them my date of birth, then we have a problem. That is when they start using knowledge of an identifier as an authentication secret.

Over the past decade or so, various institutions have been told that they can’t hold on to social security numbers, and so can’t use them for identifiers. That is a pity, because those are the best identifiers we have in the US. But what is worse is that knowledge of the new identifiers is being used for authentication.

Right now, Baskin-Robbins knows my date of birth (so they can offer me some free ice-cream on my birthday). In ten years, will I have to keep my birth date a closely guarded secret so that I don’t become a victim of some financial or medical records crime? If we keep on making this mistake – using identifiers as authentication secrets – that is where we are headed.

Incentives matter more than technology

I do not want to dismiss the technological hurdles in fixing this problem, but I believe that there is a bigger (and harder) problem that will need to be fixed first: the incentives are in the wrong place.

When Fraudster Freddy gets a loan from Bank Bertha using the identity of Victim Victor, Bertha is (correctly) responsible for the direct financial loss. The problem is that there are costs beyond the immediate fraudulent loan that are borne by Victor. But Victor has no capacity or opportunity to prevent himself from being a victim. In economics jargon, Victor suffers a negative externality.

Bertha factors in the risk of the direct cost to her of issuing a loan to a fraudster. She looks at that risk when deciding how thoroughly to check that Freddy is who he says he is. Bertha could insist that new customers submit notarized documents, but if she insists on that and her competitors don’t, then she would lose business to those competitors.

But Bertha does not factor in the indirect costs to Victor. She has no dealings with Victor. Victor isn’t a potential customer. So if Victor has costly damage to his credit and reputation that requires a lot of effort to sort out, that is not Bertha’s problem (and it certainly isn’t Freddy’s problem.)

Only when Freddy and Bertha (the parties to the original deal) have to pay the cost of the damage done to Victor (Economics jargon: “internalizing the externalities”) will Bertha have the incentives to improve authentication. I don’t have an answer to how we get there from here, but that is the direction we need to head. In the meantime, if you find yourself a victim (whether you’re a Victor, a Jeffrey, or something else entirely), Kate published a post earlier this week with tips to protect yourself until we (hopefully) do get all of this figured out one day.

11 replies
  1. dfs
    dfs says:

    You are really constructing an argument that we need new and better identifiers, and certainly that we should never rely on information about ourselves that is publicly available. For one reason or another, within a minute on Google somebody could find out info on me like my d. o. b. and my mother’s maiden name. Another thing we could do is pass laws holding organizations that store confidential information about us, above all our SSN’s, more accountable for maintaining security. A few successful class action suits would do wonders to turn this situation around.

    • Jeffrey Goldberg
      Jeffrey Goldberg says:

      My argument isn’t quite that. It’s not about having better identifiers, it is about not using indentifiers for authentication. And the problem isn’t your SSN leaking; the problem is that this non-secret can be used to damage you.

      I am not advocating a particular policy, but perhaps courts being friendly to Victor suing Bertha (in my scenario) would help to internalize the externality. My guess (and purely a guess) is that it would require supporting legislation.

  2. Tangible
    Tangible says:

    I’ve long advocated that everyone should treat SSN like their name: include it on business cards, email signatures, etc. By making it blatantly public we will rob it of it’s power to hurt us. Of course, everyone must do it simultaneously.

    I agree with everything Jeffrey said but don’t understand some of the terminology: What the heque is a “cheque”?

    • Andrew Beyer
      Andrew Beyer says:

      That’s the benefit of working for a company that employs folks from all over the world. We learn and start spelling words a bunch of different ways. It only really gets confusing when people use the same word spelled two different ways in the same paragraph! 🙈

  3. David Schuetz
    David Schuetz says:

    Another example of an identifier (or a non-secret part of one) that’s become an authenticator: zip code. Frequently used now to authenticate a credit card at gas pumps.

    • Jeffrey Goldberg
      Jeffrey Goldberg says:

      I’ve been meaning to write about that for a while. Here is a picture I took a few years back at a gas station in the 75075 ZIP code.

      Credit card auth by zipcode keypad

  4. Michael
    Michael says:

    Recently I had to accompany my mother, who is 89 years old and has some dementia, to her bank. They had suddenly and without notice disabled her debit card (she goes grocery shopping once per week with other residents of her assisted living facility and having her use a debit card is much easier than cash). We explained the issue the nice lady at the bank who immediately asked my mother for her driver’s license. Well, this is an extremely touchy subject with her as we had taken her car away and told her that the doctor had ordered her driver’s license cancelled. The nice lady at the bank informed us that without photo ID she could not help my mother or even tell her why her card was invalid. Mother offered to go home and get some photos of her ranging through the years. She knew she had one of her attending a birthday party, and one at a picnic and some others in a drawer. The nice lady at the bank again told us that she could not provide any assistance. As we were leaving, the nice lady at the bank pulled me aside and informed me that I could call their 800 number and they would send her a new card immediately. So, the nice lady at the bank could not assist us or even discuss what was going on, but, from the parking lot I could call the 800 number and get her taken care of. She had a new card in three days. Great secure systems we have…

    • Kate Sebald
      Kate Sebald says:

      It does kind of make you cringe, doesn’t it, Michael? I was personally among the folks affected by this breach and I’m trying oh-so-hard to be hopeful that it will light a fire under the financial industry’s … um, bottoms … but I must admit staying positive is tough.

      I definitely understand the nice lady at the bank’s predicament. Here you are with your lovely mother who’s in a tough situation and nice bank lady wants nothing more than to help you. I have the same experience all the time in answering questions from our customers who have lost access to their registered e-mail address or are frustrated that I can’t reset their Master Password for them. It seems convenience and security are constantly in conflict. It’s important for all organizations handling sensitive information to balance these competing priorities and I like to think 1Password does a good job of this. I know some do think we over-prioritize security, but I personally take this as a compliment. It seems too often companies let convenience override security interests. I’m sure it would be hard for the nice lady at the bank to turn you and your mother away without any solution to your problem (and that it would be frustrating for you to need to obtain some sort of photo ID for your mother), but it really would be indicative of a better and more secure system had your conversation with the bank ended before the nice lady shared the information about the 800 number.

      We humans really aren’t big picture, long term thinkers and we will need to change our own tendencies and priorities as well if we want to push financial institutions towards something better. More than just accepting some inconvenience in the interest of security, we need to demand that we be inconvenienced. As I mentioned before, I do hope that financial institutions and others handling our sensitive information take action on their own, but I also hope this serves as a wake-up call to all of us that it’s worth sacrificing that convenience for our long term security. We have a bunch of awesome super security-conscious customers, so I doubt I need to worry about y’all pushing the companies you work with in the right direction. Hopefully they will now be more apt to listen and take your concerns seriously. We may not have all the answers, but we can definitely do our part to push those holding our sensitive information to do better.

  5. Gam Dias
    Gam Dias says:

    Assuming our critical information is dispersed across a number of organizations, private and public, (that sometimes manifest as websites and online services, there problem is that this information is essentially insecure and there is no standard way of knowing what is safe / not safe, what can be shared with whom. Centralizing all the information is risky and would be next to impossible – the now defunct Microsoft passport and more recently perhaps Facebook, Amazon and Google might have access to that level of personal data.

    Sometime ago, I came with a Federated model where one’s identity can be purposely distributed across providers (or custodians) and the whole thing joins up using a composite key that could also involve some biometrics. Here’s the note I wrote: http://www.realtea.net/operational_model

    • Kate Sebald
      Kate Sebald says:

      Hey Gam! If there’s a silver lining here, it’s that we are now having a conversation about transmission and storage of personal data and are sharing ideas like yours to work towards a system that does keep that data safe. The reality is that this problem has only become more complex as technology, how we use certain personal data, and the systems that data interacts with have evolved. We may have reached a point where Pandora’s box can’t be closed again, but we need to have these conversations, examine the issues, and continue an open dialogue if we’re ever going to start moving in the right direction. I look forward to reading your blog and hope we can keep sharing these ideas and working towards something better. 🙂

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