Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums"
From: Tom St Denis (tomstdenis_at_iahu.ca)
Date: 09/22/04
 Previous message: Claudio: "a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 In reply to: Claudio: "a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Next in thread: Cristiano: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Reply: Cristiano: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Reply: Claudio: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Reply: Grumble: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
Date: Tue, 21 Sep 2004 22:00:40 GMT
Claudio wrote:
> Hello,
>
> This is a method for a hash function, based on a new technique (I
> think it's new, but this should be validated).
You think this is new?
> #define UL unsigned long
> #define LEFT 13
> #define RIGHT 19
>
> void round()
> {
> hash[4] += hash[0] >> RIGHT;
> hash[0] += hash[0] << LEFT;
> hash[0] += hash[1] >> RIGHT;
> hash[1] += hash[1] << LEFT;
> hash[1] += hash[2] >> RIGHT;
> hash[2] += hash[2] << LEFT;
> hash[2] += hash[3] >> RIGHT;
> hash[3] += hash[3] << LEFT;
> hash[3] += hash[4] >> RIGHT;
> hash[4] += hash[4] << LEFT;
How did you pick these values? What form of analysis led you to pick
this design?
<snip>
> It processes blocks of 800 bits. The same block is processed 3 times.
> Each time, a subblock of 160 bits is XORed with the hash block, and the
> result is mixed with itself (round() function), by making the 32 bits
> integers overlap with themselves (overlapping, and then addition modulo
> 2^32).
You use key material way too slowly.
> Can anybody tell me whether this idea is completely bad or very
> interesting ??
I can't say off the top of my head that it's weak but it certainly isn't
an interesting design. let me tell you why.
First off, I know what you are trying to do. You're trying to be the
first kid on the block with a new cipher design in the wake of the
recent attacks. Well that's just stupid and lame.
Second, competent hash designs already exist. Like using block ciphers
in various chaining modes [like what WHIRLPOOL is] are far more
effective and easier to analyze.
Third, a new "160bit hash" is like a new "1980 honda civic". Just a
bit dated.
Fourth, Why not present your design material [e.g. in the form of a
paper] before presenting the design?
> The facts:
>  The avalanche effect seems OK after 5 rounds. This has been
> empirically checked with the tests programs: ENT, NIST , DIEHARD (I
> generated a set of hashvalues, from a given 800bits block where a
> 32bits integer at a given position was incremented before generating
> the next hashvalue. I chosed the following integers: in[0] and in[24]).
ENT and DIEHARD are not hash function "analyzers". You might as well
used the algo to pick lotto numbers.
>  fast algorithm. In Assembly, the inner loop will take about 40 cycles
> by using MMX instructions, and by storing the hash block in MMX
> registers (6 cycles per DWORD processed). The processBlock() function
> will therefore take about 40*5*5 = 1000 cycles, for 100 bytes => about
> 10 cycles / byte, which is just a little bit slower than MD5.
Shifts are costly in cryptography. Not because they are slow but
because they lose information. A rotation is much more useful and on
the AMD they're just as expensive as a shift [being that the AMD
processors have real ALUs....].
> Thanks a lot in advance for your remarks (sorry for my nonperfect
> english).
Oh your English is ok. Your presentation just sucks.
Tom
 Previous message: Claudio: "a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 In reply to: Claudio: "a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Next in thread: Cristiano: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Reply: Cristiano: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Reply: Claudio: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Reply: Grumble: "Re: a new very fast hash algorithm (160 bits), with a technique of "overlapping sums""
 Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
Relevant Pages
