DonationCoder.com Software > N.A.N.Y. 2019

This is an entry for NANY 2019 - SCrypt

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KodeZwerg:
You really should post at least some relevant code fragments, otherwise noone will believe that you´re doing really a usable encryption. I also posted such an experimental (super-)encryption tool a few years ago and it was necessary to publish the source also.
The same problem came up with a game solving AI robot at a coding contest. Nobody believed that I was able to find the best solution within a few nanoseconds while the best were not able to break the milliseconds barrier and some others needed several seconds. They didn´t believe that this is technically possible until I released the sourcecode.
-Crush (August 22, 2018, 06:25 AM)
--- End quote ---
Okay, here we go

--- Code: Delphi ---type  AllBytes = array of Int64; var  i, NumOfBytes : Integer;  NextKey, CurrentByte : Int64; procedure Crypt(var ManyBytes : AllBytes);begin  for i := 0 to NumOfBytes - 1 do    begin      CurrentByte := ManyBytes[i];//      NextKey := *removed*      asm        MOVQ mm0, NextKey; // <- store NextKey        MOVQ mm1, CurrentByte; // <- store CurrentByte        PXOR mm1, mm0; // <- at this point we have XOR cryption done via MMX        MOVQ  CurrentByte, mm1; // give result back        EMMS;      end;      ManyBytes[i] := CurrentByte;    end;end;That represent main crypto part. Feel free to use or examine. I've slightly commented it.
Only missing Part to get it straight working is my Array for NextKey Values.

Crush:
Looks like a straight forward xor from byte to byte - no salt, password or any other "security". No complex code and I see no higher protection. Bad to read, but not too hard to crack. The "real" scrypt is incredible much better. There´s a lot of space to improve your method - do this with an additional keyword that you procede the same way.

KodeZwerg:
For the type of how it is used here, it is more than good enough. Intention was to (client side) crypt on the fly, send data via udp or tcp/ip, (server side) decrypt on the fly, done. Imagine a crypted Chat-Session for example. What i wrote in Post #1 should match. I am no expert but have experience and always interested in other ways to reach goal. My goal was to quick de-/crypt data, nothing more nothing less.

For a crypto competion i have talent enough to create something way better, but that was not focus of this project, just speed.

Crush:
For speed there´s still place for optimization  :D

f0dder:
I hope your "NumOfBytes" is badly named, and is really "NumOfInt64Blocks" :-)

Unless your "//      NextKey := *removed*" fetches a value from a One-Time-Pad with the same length as the data you're encrypting, that you're never re-using the OTP, and that you have a guaranteed non-surveilled channel for getting the OTP to the other side... then this is pretty useless.

I'm sorry if "useless" seems like a harsh word, but it's true nonetheless. If there's any reason to use crypto at all, use proper crypto. A scheme like this is definitely not good enough for "a crypted Chat-Session" - if you're discussing sensitive matters you need a whole lot more (there are perfectly good reasons Signal has a complex protocol), if you're not... well, who cares, send plaintext or use a HTTPS connection. Doesn't matter much if NSA knows when you're gonna hook up with your girlfriend, or what groceries you need to pick up on your way home from work :-)

Also, the code is pretty slow - no loop unrolling, and EMMS'ing for every block? Ouch! :)

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