Re: [cryptography] Compositing Ciphers?

----- Forwarded message from Natanael ----- Date: Sat, 7 Sep 2013 02:53:22 +0200 From: Natanael To: noloader@gmail.com Cc: Cryptography List Subject: Re: [cryptography] Compositing Ciphers? http://blog.cryptographyengineering.com/2012/02/multiple-encryption.html Apparently it's called "cascade encryption" or "cascade encipherment", and the implementations are apparently called "robust combiners". And by the way, Truecrypt already lets you pick your chosen combo of AES and two other ciphers. I think you should worry about your PRNG and it's seed before you focus on AES. Your key should both have enough entropy and be secret. Is your PRNG backdoored already? And I'm guessing the cipher mode probably matters a bit more than the exact choice of algorithm. On Sat, Sep 7, 2013 at 2:27 AM, Jeffrey Walton wrote:

Hi All,

With all the talk of the NSA poisoning NIST, would it be wise to composite ciphers? (NY Times, Guardian, Dr. Green's blog, et seq).

I've been thinking about running a fast inner stream cipher (Salsa20 without a MAC) and wrapping it in AES with an authenticated encryption mode (or CBC mode with {HMAC|CMAC}).

I'm aware of, for example, NSA's Fishbowl running IPSec at the network layer (the "outer" encryption") and then SRTP and the application level (the "inner" encryption). But I'd like to focus on hardening one cipherstream at one level, and not cross OSI boundaries.

I'm also aware of the NSA's lightweight block ciphers (http://eprint.iacr.org/2013/404). I may have been born at night, but it was not last night....

Has anyone studied the configuration and security properties of a inner stream cipher with an outer block cipher?

Jeff _______________________________________________ cryptography mailing list cryptography@randombit.net http://lists.randombit.net/mailman/listinfo/cryptography

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