%    Copyright (C) 1996, 1997 Geoffrey Keating. % This file may be freely distributed with or without modifications,% so long as proper attribution is given and copyright notices are% not removed. % pdf_sec.ps (version 1.0.3)% Implementation of security hooks for PDF reader. % This file contains the procedures that have to take encryption into% account when reading a PDF file. It replaces the stub version of this% file that is shipped with GhostScript. It requires GhostScript version 4.02% or later. /.setlanguagelevel where { pop 2 .setlanguagelevel } if.currentglobal true .setglobal/pdfdict where { pop } { /pdfdict 100 dict def } ifelsepdfdict begin % Older ghostscript versions do not have .pdftoken, so we use 'token' instead./.pdftoken where { pop } { /.pdftoken /token load def } ifelse % An implementation of an algorithm compatible with the RSA Data Security % Inc. RC4 stream encryption algorithm. % <string> rc4setkey <dict>/rc4setkey{  6 dict begin    /k exch def    /a 256 string def    0 1 255 { a exch dup put } for    /l k length def    /j 0 def    0 1 255    {      /i exch def      /j a i get k i l mod get add j add 255 and def      a i a j get a j a i get put put    } for    3 dict dup begin      /a a def      /x 0 def      /y 0 def    end  end} bind def % <rc4key> <string> rc4 <string> <rc4key>/rc4{  1 index begin    dup dup length 1 sub 0 exch 1 exch    {      /x x 1 add 255 and def      /y a x get y add 255 and def      a x a y get a y a x get put put% stack: string string index      2 copy get      a dup x get a y get add 255 and get      xor put dup    } for    pop  end} bind def % take a stream and rc4 decrypt it.% <stream> <key> rc4decodefilter <stream>/rc4decodefilter {  currentglobal exch true setglobal  dup length string copy rc4setkey  exch setglobal  exch 512 string   % stack: <key> <stream> <string>  { readstring pop rc4 exch pop } aload pop   8 array astore cvx 0 () /SubFileDecode filter } bind def % MD5 derived from RFC 1321, "The MD5 Message-Digest Algorithm",% R. Rivest, MIT, RSADSI; implemented in PostScript by Geoffrey Keating. % We construct the MD5 transform by a sort of inline expansion.% this takes up quite a bit of memory (around 17k), but gives a% factor-of-two speed increase.% This also allows us to take advantage of interpreters with 64-bit% wide integers.% This will not run on interpreters with 16-bit wide integers, if such% things exist.20 dict begin /T [16#d76aa478 16#e8c7b756 16#242070db 16#c1bdceee16#f57c0faf 16#4787c62a 16#a8304613 16#fd46950116#698098d8 16#8b44f7af 16#ffff5bb1 16#895cd7be16#6b901122 16#fd987193 16#a679438e 16#49b4082116#f61e2562 16#c040b340 16#265e5a51 16#e9b6c7aa16#d62f105d 16#02441453 16#d8a1e681 16#e7d3fbc816#21e1cde6 16#c33707d6 16#f4d50d87 16#455a14ed16#a9e3e905 16#fcefa3f8 16#676f02d9 16#8d2a4c8a16#fffa3942 16#8771f681 16#6d9d6122 16#fde5380c16#a4beea44 16#4bdecfa9 16#f6bb4b60 16#bebfbc7016#289b7ec6 16#eaa127fa 16#d4ef3085 16#04881d0516#d9d4d039 16#e6db99e5 16#1fa27cf8 16#c4ac566516#f4292244 16#432aff97 16#ab9423a7 16#fc93a03916#655b59c3 16#8f0ccc92 16#ffeff47d 16#85845dd116#6fa87e4f 16#fe2ce6e0 16#a3014314 16#4e0811a116#f7537e82 16#bd3af235 16#2ad7d2bb 16#eb86d391] def/F [{ c d /xor b /and d /xor } { b c /xor d /and c /xor }{ b c /xor d /xor } { d /not b /or c /xor }] def/R [16#0007 16#010c 16#0211 16#0316 16#0407 16#050c 16#0611 16#071616#0807 16#090c 16#0a11 16#0b16 16#0c07 16#0d0c 16#0e11 16#0f1616#0105 16#0609 16#0b0e 16#0014 16#0505 16#0a09 16#0f0e 16#041416#0905 16#0e09 16#030e 16#0814 16#0d05 16#0209 16#070e 16#0c1416#0504 16#080b 16#0b10 16#0e17 16#0104 16#040b 16#0710 16#0a1716#0d04 16#000b 16#0310 16#0617 16#0904 16#0c0b 16#0f10 16#021716#0006 16#070a 16#0e0f 16#0515 16#0c06 16#030a 16#0a0f 16#011516#0806 16#0f0a 16#060f 16#0d15 16#0406 16#0b0a 16#020f 16#0915] def /W 1 31 bitshift 0 gt def/A W { /add } { /md5add } ifelse def/t W { 1744 } { 1616 } ifelse array def/C 0 def 0 1 63 {  /i exch def  /r R i get def  /a/b/c/d 4 i 3 and roll [ /d/c/b/a ] { exch def } forall   t C [    a F i -4 bitshift get exec     a A /x r -8 bitshift /get A T i get A    W { 1 32 bitshift 1 sub /and } if    /dup r 31 and /bitshift /exch r 31 and 32 sub /bitshift /or    b A    /def  ] dup length C add /C exch def putinterval} for 1 1 C 1 sub {  dup 1 sub t exch get /def cvx eq    {pop}    {t exch 2 copy get cvx put}  ifelse} for % If we could put t into a _packed_ array, its memory requirements% would go from about 13k to about 4k. Unfortunately, we'd need around% 1600 stack positions, around 3 times what we can expect to have % available---and if that kind of memory is available, we don't really% need to pack t. Sigh. % In fact, it's worse than that. You can't even determine what t will % be and write it in directly (something like% { /a c d xor b and d xor a md5add x 0 get md5add -680876936 md5add dup 7 %   bitshift exch -25 bitshift or b md5add def /d b c xor a ...% ) because the scanner uses the operand stack to accumulate procedures.% So the only way to have md5transform as a single procedure is the above % trick. W /md5transform t end cvx bind def % Unfortunately, PostScript & its imitators convert large% integers to floating-point. Worse, the fp representation probably% won't have 32 significant bits.% This procedure accounts for about 35% of the total time on 32-bit % machines.not {  /md5add {    2 copy xor 0 lt      % if one is positive and one is negative, can't overflow      { add }      % if both are positive or negative      { 16#80000000 xor add 16#80000000 xor }      % same as subtracting (or adding) 2^31 and then subtracting (or       % adding) it back.    ifelse  } bind def} {  /md5add {    add 16#0FFFFFFFF and  } bind def} ifelse /md5 {  20 dict begin   % initialise a,b,c,d,x  /a 16#67452301 def  /b 16#efcdab89 def  /c 16#98badcfe def  /d 16#10325476 def  /x 16 array def   % parameters  /origs exch def  /oslen origs length def   % pad string to multiple of 512 bits  /s oslen 72 add 64 idiv 64 mul dup /slen exch def string def  s 0 origs putinterval  s oslen 16#80 put  s slen 8 sub oslen 31 and 3 bitshift put  s slen 7 sub oslen -5 bitshift 255 and put  s slen 6 sub oslen -13 bitshift 255 and put   0 64 slen 64 sub {    dup 1 exch 63 add { s exch get } for    15 -1 0 { x exch 6 2 roll 3 { 8 bitshift or } repeat put } for    a b c d    md5transform    d md5add /d exch def    c md5add /c exch def    b md5add /b exch def    a md5add /a exch def  } for    16 string  [ [ a b c d ] { 3 { dup -8 bitshift } repeat } forall ]  0 1 15 {    3 copy dup 3 1 roll get 255 and put pop  } for  pop   end} bind def % Pad a key out to 32 bytes./pdf_pad_key		% <key> pdf_pad_key <padded key> { dup length 32 gt { 0 32 getinterval } if   <28bf4e5e4e758a41 64004e56fffa0108    2e2e00b6d0683e80 2f0ca9fe6453697a>   0 32 3 index length sub getinterval   concatstrings } bind def % Try a user key for a PDF file./pdf_try_key		% <key> pdf_try_key <filekey> true			% <key> pdf_try_key false { Trailer /Encrypt oget   dup /O oget exch   /P oget 4 string exch	 2 copy 255 and 0 exch put	 2 copy -8 bitshift 255 and 1 exch put	 2 copy -16 bitshift 255 and 2 exch put	 2 copy -24 bitshift 255 and 3 exch put pop   Trailer /ID oget 0 oget   3 { concatstrings } repeat   md5 0 5 getinterval   dup   Trailer /Encrypt oget /U oget dup length string copy exch   rc4setkey exch rc4 exch pop   <28bf4e5e4e758a41 64004e56fffa0108    2e2e00b6d0683e80 2f0ca9fe6453697a> eq   dup not { exch pop } if } bind def % Process the encryption information in the Trailer./pdf_process_Encrypt { Trailer /Encrypt oget   /Filter oget /Standard eq not    { (****This file uses an unknown security handler.\n) print flush	/pdf_process_Encrypt cvx /undefined signalerror    }   if   () pdf_pad_key pdf_try_key    { /FileKey exch def }     { /PDFPassword where       { PDFPassword pdf_pad_key pdf_try_key 	  { true }	  { PDFPassword pdf_pad_key md5 0 5 getinterval rc4setkey	    Trailer /Encrypt oget /O oget dup length string copy	       rc4 exch pop	    pdf_try_key	  }	 ifelse	  { /FileKey exch def }	  { (****Password did not work.\n) print flush	    /pdf_process_Encrypt cvx /invalidfileaccess signalerror	  }	 ifelse       }       { (****This file has a user password set.\n) print flush	 /pdf_process_Encrypt cvx /invalidfileaccess signalerror       }      ifelse    }   ifelse   Trailer /Encrypt oget /P oget 4 and 0 eq #? and    { (****This owner of this file has requested you do not print it.\n)	print flush      /pdf_process_Encrypt cvx /invalidfileaccess signalerror    }   if } bind def % Calculate the key used to decrypt an object (to pass to .decpdfrun or% put into a stream dictionary)./computeobjkey	% <object#> <generation#> computeobjkey <keystring>{  exch  10 string  dup 0 FileKey putinterval  exch		% stack:  gen# string obj#    2 copy 255 and 5 exch put    2 copy -8 bitshift 255 and 6 exch put    2 copy -16 bitshift 255 and 7 exch put  pop exch    2 copy 255 and 8 exch put    2 copy -8 bitshift 255 and 9 exch put  pop md5 0 10 getinterval} bind def % As .pdfrun, but decrypt strings with key <key>./.decpdfrun			% <file> <keystring> <opdict> .decpdfrun - {	% Construct a procedure with the file, opdict and key bound into it.   2 index cvlit mark mark 5 2 roll    { .pdftoken not { (%%EOF) cvn cvx } if      dup xcheck       { DEBUG { dup == flush } if	 3 -1 roll pop	 2 copy .knownget	  { exch pop exch pop exec }	  { (%stderr) (w) file	    dup (****************Unknown operator: ) writestring	    dup 3 -1 roll .writecvs dup (\n) writestring flushfile	    pop	  }	 ifelse       }       { exch pop DEBUG { dup ==only ( ) print flush } if	 dup type /stringtype eq	  { exch rc4setkey exch rc4 }	 if	 exch pop       }      ifelse    }   aload pop .packtomark cvx   /loop cvx 2 packedarray cvx    { stopped /PDFsource } aload pop   PDFsource    { store { stop } if } aload pop .packtomark cvx    /PDFsource 3 -1 roll store exec } bind def % Run the code to resolve an object reference./pdf_run_resolve { /FileKey where    { pop      2 copy computeobjkey dup 4 1 roll      PDFfile exch resolveopdict .decpdfrun      dup dup dup 5 2 roll	% stack: object object key object object      xcheck exch type /dicttype eq and       { /StreamKey exch put }       { pop pop }      ifelse    }    { PDFfile resolveopdict .pdfrun }   ifelse } bind def % Prefix a decryption filter to a stream if needed.% Stack: readdata? dict parms file/string filternames% (both before and after)./pdf_decrypt_stream { 3 index /StreamKey known   {      exch 	% Stack: readdata? dict parms filternames file/string      3 index /Length oget () /SubFileDecode filter      3 index /StreamKey get rc4decodefilter      exch   } if } bind def end			% pdfdict.setglobal