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Diffstat (limited to 'kghostview/data/pdf_sec.ps')
| -rw-r--r-- | kghostview/data/pdf_sec.ps | 386 |
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diff --git a/kghostview/data/pdf_sec.ps b/kghostview/data/pdf_sec.ps new file mode 100644 index 00000000..5fe9598a --- /dev/null +++ b/kghostview/data/pdf_sec.ps @@ -0,0 +1,386 @@ +% Copyright (C) 1996-1998 Geoffrey Keating. +% This file may be freely distributed with or without modifications, +% so long as modified versions are marked as such and copyright notices are +% not removed. + +% pdf_sec.ps (version 1.0.4) +% 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. + +% Documentation for using this file is available at +% http://www.ozemail.com.au/%7Egeoffk/pdfencrypt/ + +/.setlanguagelevel where { pop 2 .setlanguagelevel } if +.currentglobal true .setglobal +/pdfdict where { pop } { /pdfdict 100 dict def } ifelse +pdfdict 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#c1bdceee +16#f57c0faf 16#4787c62a 16#a8304613 16#fd469501 +16#698098d8 16#8b44f7af 16#ffff5bb1 16#895cd7be +16#6b901122 16#fd987193 16#a679438e 16#49b40821 +16#f61e2562 16#c040b340 16#265e5a51 16#e9b6c7aa +16#d62f105d 16#02441453 16#d8a1e681 16#e7d3fbc8 +16#21e1cde6 16#c33707d6 16#f4d50d87 16#455a14ed +16#a9e3e905 16#fcefa3f8 16#676f02d9 16#8d2a4c8a +16#fffa3942 16#8771f681 16#6d9d6122 16#fde5380c +16#a4beea44 16#4bdecfa9 16#f6bb4b60 16#bebfbc70 +16#289b7ec6 16#eaa127fa 16#d4ef3085 16#04881d05 +16#d9d4d039 16#e6db99e5 16#1fa27cf8 16#c4ac5665 +16#f4292244 16#432aff97 16#ab9423a7 16#fc93a039 +16#655b59c3 16#8f0ccc92 16#ffeff47d 16#85845dd1 +16#6fa87e4f 16#fe2ce6e0 16#a3014314 16#4e0811a1 +16#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#0716 +16#0807 16#090c 16#0a11 16#0b16 16#0c07 16#0d0c 16#0e11 16#0f16 +16#0105 16#0609 16#0b0e 16#0014 16#0505 16#0a09 16#0f0e 16#0414 +16#0905 16#0e09 16#030e 16#0814 16#0d05 16#0209 16#070e 16#0c14 +16#0504 16#080b 16#0b10 16#0e17 16#0104 16#040b 16#0710 16#0a17 +16#0d04 16#000b 16#0310 16#0617 16#0904 16#0c0b 16#0f10 16#0217 +16#0006 16#070a 16#0e0f 16#0515 16#0c06 16#030a 16#0a0f 16#0115 +16#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 + { pop 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 |