Does the National Security Agency (NSA) have the authority to collect and keep all encrypted Internet traffic for as long as is necessary to decrypt that traffic? That was a question first raised in June 2013, after the minimization procedures governing telephone and Internet records collected under Section 702 of the Foreign Intelligence Surveillance Act were disclosed by Edward Snowden. The issue quickly receded into the background, however, as the world struggled to keep up with the deluge of surveillance disclosures. The Intelligence Authorization Act of 2015, which passed Congress this last December, should bring the question back to the fore. It established retention guidelines for communications collected under Executive Order 12333 and included an exception that allows NSA to keep ‘incidentally’ collected encrypted communications for an indefinite period of time. This creates a massive loophole in the guidelines.
NSA’s retention of encrypted communications deserves further consideration today, now that these retention guidelines have been written into law. It has become increasingly clear over the last year that surveillance reform will be driven by technological change—specifically by the growing use of encryption technologies. Therefore, any legislation touching on encryption should receive close scrutiny.
New Retention Guidelines for Encrypted Data
Section 309 of the intel authorization bill describes “procedures for the retention of incidentally acquired communications.” It establishes retention guidelines for surveillance programs that are “reasonably anticipated to result in the acquisition of [telephone or electronic communications] to or from a United States person.” Communications to or from a United States person are ‘incidentally’ collected because the U.S. person is not the actual target of the collection. Section 309 states that these incidentally collected communications must be deleted after five years unless they meet a number of exceptions. One of these exceptions is that “the communication is enciphered or reasonably believed to have a secret meaning.”
This exception appears to be directly lifted from NSA’s minimization procedures for data collected under Section 702 of FISA, which were declassified in 2013.
While Section 309 specifically applies to collection taking place under E.O. 12333, not FISA, several of the exceptions described in Section 309 closely match exceptions in the FISA minimization procedures. That includes the exception for “enciphered” communications. Those minimization procedures almost certainly served as a model for these retention guidelines and will likely shape how this new language is interpreted by the Executive Branch. Section 309 also asks the heads of each relevant member of the intelligence community to develop procedures to ensure compliance with new retention requirements. I expect those procedures to look a lot like the FISA minimization guidelines.
FISA Minimization Procedures & Encryption
The FISA minimization procedures carve out an exception for incidentally collected U.S persons communications that are encrypted. This exception applies to what the procedures call “technical data base information,” which means, “information retained for cryptanalytic, traffic analytic, or signals exploitation purposes.”
Here is what the procedures say about how this information should be handled:
…[Technical data base information] may be retained for a period sufficient to allow a thorough exploitation and to permit access to data that are, or are reasonably believed likely to become, relevant to a current or future foreign intelligence requirement. Sufficient duration may vary with the nature of the exploitation.
1. In the context of a cryptanalytic effort, maintenance of technical data bases requires retention of all communications that are enciphered or reasonably believed to contain secret meaning, and sufficient duration may consist of any period of time during which encrypted material is subject to, or of use in, cryptanalysis.
This language is broad, circular, and technically incoherent, so it takes some effort to parse appropriately. When the minimization procedures were disclosed in 2013, this language was interpreted by outside commentators to mean that NSA may keep all encrypted data that has been incidentally collected under Section 702 for at least as long as is necessary to decrypt that data. Is this the correct interpretation? I think so.
It is important to realize that the language above isn’t just broad. It seems purposefully broad. The part regarding relevance seems to mirror the rationale NSA has used to justify its bulk phone records collection program. Under that program, all phone records were relevant because some of those records could be valuable to terrorism investigations and (allegedly) it isn’t possible to collect only those valuable records. This is the “to find a needle a haystack, you first have to have the haystack” argument. The same argument could be applied to encrypted data and might be at play here.
This exception doesn’t just apply to encrypted data that might be relevant to a current foreign intelligence investigation. It also applies to cases in which the encrypted data is likely to become relevant to a future intelligence requirement. This is some remarkably generous language. It seems one could justify keeping any type of encrypted data under this exception.
Upon close reading, it is difficult to avoid the conclusion that these procedures were written carefully to allow NSA to collect and keep a broad category of encrypted data under the rationale that this data might contain the communications of NSA targets and that it might be decrypted in the future. If NSA isn’t doing this today, then whoever wrote these minimization procedures wanted to at least ensure that NSA has the authority to do this tomorrow.
Incidental Collection vs Bulk Collection
There are a few additional observations that are worth making regarding these nominally new retention guidelines and Section 702 collection. First, the concept of incidental collection as it has typically been used makes very little sense when applied to encrypted data.
The way that NSA’s Section 702 upstream “about” collection is understood to work is that technology installed on the network does some sort of pattern match on Internet traffic; say that an NSA target uses email@example.com to communicate. NSA would then search content of emails for references to firstname.lastname@example.org. This could notionally result in a lot of incidental collection of U.S. persons’ communications whenever the email that references email@example.com is somehow mixed together with emails that have nothing to do with the target.
This type of incidental collection isn’t possible when the data is encrypted because it won’t be possible to search and find firstname.lastname@example.org in the body of an email. Instead, email@example.com will have been turned into some alternative, indecipherable string of bits on the network. Incidental collection shouldn’t occur because the pattern match can’t occur in the first place. This demonstrates that, when communications are encrypted, it will be much harder for NSA to search Internet traffic for a unique ID associated with a specific target.
This lends further credence to the conclusion above: rather than doing targeted collection against specific individuals, NSA is collecting, or plans to collect, a broad class of data that is encrypted. For example, NSA might collect all PGP encrypted emails or all Tor traffic. In those cases, NSA could search Internet traffic for patterns associated with specific types of communications, rather than specific individuals’ communications. This would technically meet the definition of incidental collection because such activity would result in the collection of communications of U.S. persons who aren’t the actual targets of surveillance. Collection of all Tor traffic would entail a lot of this “incidental” collection because the communications of NSA targets would be mixed with the communications of a large number of non-target U.S. persons.
However, this “incidental” collection is inconsistent with how the term is typically used, which is to refer to over-collection resulting from targeted surveillance programs. If NSA were collecting all Tor traffic, that activity wouldn’t actually be targeted, and so any resulting over-collection wouldn’t actually be incidental. Moreover, greater use of encryption by the general public would result in an ever-growing amount of this type of incidental collection.
This type of collection would also be inconsistent with representations of Section 702 upstream collection that have been made to the public and to Congress. Intelligence officials have repeatedly suggested that search terms used as part of this program have a high degree of specificity. They have also argued that the program is an example of targeted rather than bulk collection. ODNI General Counsel Robert Litt, in a March 2014 meeting before the Privacy and Civil Liberties Oversight Board, stated that “there is either a misconception or a mischaracterization commonly repeated that Section 702 is a form of bulk collection. It is not bulk collection. It is targeted collection based on selectors such as telephone numbers or email addresses where there’s reason to believe that the selector is relevant to a foreign intelligence purpose.”
The collection of Internet traffic based on patterns associated with types of communications would be bulk collection; more akin to NSA’s collection of phone records en mass than it is to targeted collection focused on specific individuals. Moreover, this type of collection would certainly fall within the definition of bulk collection provided just last week by the National Academy of Sciences: “collection in which a significant portion of the retained data pertains to identifiers that are not targets at the time of collection.”
Changing the Scope of Encrypted Data Collection
The Section 702 minimization procedures, which will serve as a template for any new retention guidelines established for E.O. 12333 collection, create a large loophole for encrypted communications. With everything from email to Internet browsing to real-time communications moving to encrypted formats, an ever-growing amount of Internet traffic will fall within this loophole.
This is not to suggest that the collection, analysis, and retention of these data are entirely inappropriate. I suspect there are many cases in which retention of encrypted data for longer than five years is quite justifiable. The problem here is the breadth of collection that might take place under this exception. This could result in massive over collection on a troubling scale. Below are four actionable steps than can be taken to address this concern:
- If it is the case that NSA is collecting a broad category of encrypted data under Section 702 authorities, intelligence officials should correct the public record regarding the targeted or bulk character of upstream Section 702 collection.
- The exception for retention of incidentally collected encrypted communications should be clarified and narrowed in the FISA minimization procedures. At a minimum, retention for possible “future” intelligence requirements should be barred.
- This exception should similarly be clarified and narrowed for collection of encrypted communications under E.O. 12333, in accordance with Section 309.
- Congress and the FISC should closely examine how the exemption for encrypted communications in the Section 702 is being interpreted. If necessary, Congress should consider modifying newly established retention guidelines to more clearly identify the circumstances under which encrypted data may be retained.