Re: [Cfrg] Analysis of ipcrypt?

Russ Housley <housley@vigilsec.com> Thu, 22 February 2018 23:30 UTC

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From: Russ Housley <housley@vigilsec.com>
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Date: Thu, 22 Feb 2018 18:30:36 -0500
Cc: Samuel Neves <sneves@dei.uc.pt>, IRTF CFRG <cfrg@irtf.org>, "Jason A. Donenfeld" <Jason@zx2c4.com>
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To: Paul Hoffman <paul.hoffman@icann.org>
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Subject: Re: [Cfrg] Analysis of ipcrypt?
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Paul:

It sounds like you want a simple and straightforward way to obfuscate IPv4 addresses.

AES is very widely implemented.  You can find libraries for every platform.  So, something like this may do it for you:

	k = rand()  /* 128 bits; fresh key for each dataset */

	for each ipv4addr in dataset:
		plain = ipv4addr || ipv4addr || ipv4addr || ipv4addr
		obfuscated_ipv4addr = trunc32(AES_128_Encrypt(k, plain))

It is easy to go from 32-bit unsigned values to dotted notation and back if needed.

Russ



> On Feb 22, 2018, at 1:11 , Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> 
> Hi Paul,
> 
> Found this last night shortly after you posted this message. The
> attached program Samuel (CC'd) and I just drummed up may be cause for
> concern. You may not want to use ipcrypt.
> 
> Regards,
> Jason