Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth

From	Paul Rubin <no.email@nospam.invalid>
Newsgroups	comp.lang.forth
Subject	Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth
Date	2012-12-21 20:07 -0800
Organization	Nightsong/Fort GNOX
Message-ID	<7xr4mi6871.fsf@ruckus.brouhaha.com> (permalink)
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Bernd Paysan <bernd.paysan@gmx.de> writes:
> Ok, let's say there exist cryptographers who still recommend using block 
> ciphers (you'll probably find them if you search long enough ;-).  I 
> wouldn't.

Really, for most real-world applications, AES is the only thing that
makes sense, due to its standardization if nothing else.  It's more a
matter of following recognized practices than of doing something that's
arguably better technically.  

> * The mode where you actually need the properties of the block cipher, 
> ECB, is foolish.

The presumption in any case is that you know what you're doing with
regard to mode selection.

> * The other modes don't give you authentication, so you need another 
> primitive or at least another go with a different key for
> authentication 

CCM, GCM, OCB, and various other modes support encryption and
authentication with a single key (split into two derived keys as part of
the protocol).  GCM is probably still the favorite.  AESNI even has
special new hardware to support it (the binary field operations).

> for any a!=b, the transfer function f(a)!=f(b)....  This is similar in
> structure to one of the key attack vectors of the Enigma

This is not a problem if the block size is big enough.  You need on the
order of 2**(blocksize/2) blocks of ciphertext to notice the difference
between the block cipher and a random function (this is proved by a theorem
called the PRP-PRF switching lemma).  It's part of the reason AES has
128 bit blocks when most earlier block ciphers had 64 bits.

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Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-12 14:52 -0800
  Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Howerd <howerdo@yahoo.co.uk> - 2012-12-12 23:47 -0800
    Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-13 00:38 -0800
      Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Howerd <howerdo@yahoo.co.uk> - 2012-12-13 20:17 -0800
        Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-13 20:25 -0800
          Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Howerd <howerdo@yahoo.co.uk> - 2012-12-13 20:53 -0800
            Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-13 21:16 -0800
              Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Howerd <howerdo@yahoo.co.uk> - 2012-12-14 03:43 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-14 12:15 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-20 00:21 -0800
            Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-14 04:45 -0600
              Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Howerd <howerdo@yahoo.co.uk> - 2012-12-14 03:33 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-14 12:20 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-14 10:28 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-14 12:39 -0600
          Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-15 01:47 +0100
            Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-19 18:10 -0800
              Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-19 19:53 -0800
              Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-20 14:44 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-20 19:28 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-20 13:56 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-21 01:41 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-21 03:58 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-21 02:20 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-21 06:46 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-21 15:34 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-21 08:40 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-22 03:36 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-21 20:07 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-23 02:37 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-22 19:24 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-23 15:52 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-23 17:52 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-24 03:57 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-24 16:20 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-24 15:36 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-25 02:52 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-24 21:51 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-25 20:56 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Paul Rubin <no.email@nospam.invalid> - 2012-12-26 01:08 -0800
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-26 16:02 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth David Thompson <dave.thompson2@verizon.net> - 2012-12-31 02:48 -0500
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth kenney@cix.compulink.co.uk - 2012-12-24 03:20 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-22 03:24 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-23 01:24 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-23 04:59 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-23 17:32 +0100
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-12-23 11:28 -0600
                Re: ANN: SHA-256 Secure Hash Algorithm in ANS Forth Bernd Paysan <bernd.paysan@gmx.de> - 2012-12-24 00:30 +0100

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