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   comp.lang.asm.x86      Ahh, the lost art of x86 assembly      4,675 messages   

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   Message 2,686 of 4,675   
   Terje Mathisen to wolfgang kern   
   Re: BASE64 again   
   16 Jun 17 16:40:59   
   
   From: terje.mathisen@nospicedham.tmsw.no   
      
   wolfgang kern wrote:   
   > seems I played this game for too long...   
   > my brain works still on it even when I sleep :)   
   > Terje asked for another 2:1 algo:   
   > I gave up on the hex idea because of the sub 07 and the missing   
   > first/second indicator, but why not use the given ranges a bit different   
   > ? So a 4+4 bit algo may use the low nibble of "A...P" (41..50) to   
   > produce 10..f0 (00 with 50) by shl,4 from first byte and 01..0f of   
   > "a..p"(61..70) by AND&OR from every second byte.   
   > in addition I made use of many filler bytes to modify alot:   
   >   
   > ZRRh61XPR560PRR4dPjDa-rY1G`Ss$anytext#<=t7r4 66hwAX(G%(g/(G3(g8(g9(G0)G1(g:eeee+++   
   >   
   > it didn't become shorter than the xor-sub-sub would show with my   
   > extended use of printable characters. Just an idea    __   
   > wolfgang   
      
   One of the key requirements is of course that your algorithm must only   
   use the blessed (MIME) opcodes, this means that SHL/ROL/ROR/ADD/ADC are   
   all off the table!   
      
   SUB'ing twice was my workaround for this problem while XOR was the   
   easiest way to combine two bytes.   
      
   Terje   
      
   --   
   -    
   "almost all programming can be viewed as an exercise in caching"   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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