MAC Address Anonymization

MAC Address anonymization is the idea of performing a one way function on a MAC address so that the result may be used in tracking systems for reporting and the general public, while making it nearly impossible to obtain the original MAC Address from the result. The idea is that this process allows companies like Google,[1] Apple[2] and iInside[3] - which track users movements via computer hardware to simultaneously preserve the identities of the people they are tracking, as well as the hardware itself.

Examples

An easy example of MAC address anonymization would be to use a simple hash algorithm. Given an address of 11:22:33:44:55, the MD5 hash algorithm produces 8,093,140,232,281,458,246 (0x70509c29768f0646).

An address only one character different (11:22:33:44:56) produces 1,390,925,306,346,392,705 (0x134d8f3259e0cc81), an entirely different number.

Why this does not work in practice

Tracking companies rely on the assumption that address anonymization is akin to encryption. Given a message, and an encryption method that is well known to both the encoder and potential decryptor, modern encryption methods (such as AES or RSA will yield a result that is unbreakable in practice.

The problem lies in the fact that there are only 248 (281,474,976,710,656 ) possible MAC addresses. Given the encoding algorithm, an index an easily be created for each possible address.

Several years ago, the building of such an index would have been difficult due to the compute time involved. With modern, parallel, cloud computing, the index generation can be easily divided among the number of processors desired.

On a 2.5 GHz processor, a C# program was able to produce the following results:

CPU Count Iterations Time (seconds)
1 2.814 x 1014 3.0489 x 10−6
1,000 2.814 x 1011 3.0489 x 10−3
1,000,000 2.814 x 108 304.89

Thus, a million processors could create the entire index in just over five minutes, and 100,000 processors in less than 85 hours. Once the index is complete, conversions of "anonymized" addresses to their actual addresses is almost instantaneous.

References

  1. ↑ "Google Maps Has Been Tracking Your Every Move, And There's A Website To Prove It". Junkee. Retrieved 2016-04-10.
  2. ↑ "How your iPhone has been tracking your every move in secret | Metro News". Metro.co.uk. 2014-09-28. Retrieved 2016-04-11.
  3. ↑ "iInside retail brochure: Leading the market in indoor location techno…". 2014-03-10.


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