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Saving private spying: IETF Draft reveals crypto-busting proxy proposal

'Explicit Trusted Proxy' would allow carriers to decrypt data to speed transmission

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A draft put forward to the Internet Engineering Task Force has drawn the ire of prominent privacy activist Lauren Weinstein as “one of the most alarming Internet proposals” he's ever seen.

The document that's upset Weinstein is this one, out of the HTTPBis Working Group and posted as an Internet Draft on 14 February 2014.

Entitled Explicit Trusted Proxy in HTTP/2.0, the standard proposes a mechanism by which an upstream provider – say an ISP – could get permission to snoop on decrypt user traffic for the purposes of caching.

Using proxies to cache traffic in the service provider network is unremarkable and uncontroversial: it's been normal practice for a long time. The end user benefit is better performance; the service provider benefit is a reduction in traffic over their upstream transit network links.

From that point of view, encryption is a pain in the neck: the service provider can't see into the encrypted traffic, which reduces the effectiveness of its caching strategy.

The Internet Draft has this to say:

“To distinguish between an HTTP2 connection meant to transport "https" URIs resources and an HTTP2 connection meant to transport "http" URIs resource, the draft proposes to 'register a new value in the Application Layer Protocol negotiation (ALPN) Protocol IDs registry specific to signal the usage of HTTP2 to transport "http" URIs resources: h2clr.'”

In essence, to try and protect their ability to cache, the authors of the standard propose that providers seek their customers' permission to decrypt their traffic (solely for the purposes of offering a better customer experience, naturally).

For some reason, Weinstein finds this proposal outrageous: “The proposal expects Internet users to provide 'informed consent' that they 'trust' intermediate sites (e.g. Verizon, AT&T, etc.) to decode their encrypted data, process it in some manner for 'presumably' innocent purposes, re-encrypt it, then pass the re-encrypted data along to its original destination,” he writes.

“The assumption that users can even be expected to make truly informed decisions about this seems highly problematic,” he writes, concluding “The concept of "trusted proxies" as proposed is inherently untrustworthy, especially in this post-Snowden era.”

Nor is he impressed with the authors' plea that a trusted proxy is better than having service providers get their proxying to work by a transparent man-in-the-middle attack: "Fundamentally this is like arguing that execution by lethal injection is less cruel than by electric chair. This may be strictly true, but the target of the procedure ends up dead either way," Weinstein told The Register.

It probably won't surprise the reader to know that the proposal is sponsored by AT&T. ®

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