66 lines
2.5 KiB
PostScript
66 lines
2.5 KiB
PostScript
% Copyright (C) 1992, 1993 Aladdin Enterprises. All rights reserved.
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%
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% This software is provided AS-IS with no warranty, either express or
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% implied.
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%
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% This software is distributed under license and may not be copied,
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% modified or distributed except as expressly authorized under the terms
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% of the license contained in the file LICENSE in this distribution.
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%
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% For more information about licensing, please refer to
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% http://www.ghostscript.com/licensing/. For information on
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% commercial licensing, go to http://www.artifex.com/licensing/ or
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% contact Artifex Software, Inc., 101 Lucas Valley Road #110,
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% San Rafael, CA 94903, U.S.A., +1(415)492-9861.
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% $Id: type1enc.ps,v 1.4 2002/02/21 21:49:28 giles Exp $
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% type1enc.ps
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% PostScript language versions of the Type 1 encryption/decryption algorithms.
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% This file is normally not needed with Ghostscript, since Ghostscript
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% implements these algorithms in C. For the specifications, see Chapter 7 of
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% "Adobe Type 1 Font Format," ISBN 0-201-57044-0, published by Addison-Wesley.
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/.type1crypt % <R> <from> <to> <proc> .type1crypt <R'> <to>
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% (auxiliary procedure)
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{ 4 1 roll
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0 2 index length getinterval
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0 1 2 index length 1 sub
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{ % Stack: proc R from to index
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2 index 1 index get % proc R from to index C/P
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4 index -8 bitshift xor 3 copy put % proc R from to index P/C
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5 index exec % proc R from to C
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% Compute R' = ((R + C) * 52845 + 22719) mod 65536
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% without exceeding a 31-bit integer magnitude, given that
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% 0 <= R <= 65535 and 0 <= C <= 255.
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4 -1 roll add
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dup 20077 mul % 52845 - 32768
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exch 1 and 15 bitshift add % only care about 16 low-order bits
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22719 add 65535 and 3 1 roll
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}
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for exch pop 3 -1 roll pop
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} bind def
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% <state> <fromString> <toString> .type1encrypt <newState> <toSubstring>
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% Encrypts fromString according to the algorithm for Adobe
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% Type 1 fonts, writing the result into toString.
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% toString must be at least as long as fromString or a
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% rangecheck error occurs. state is the initial state of
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% the encryption algorithm (a 16-bit non-negative
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% integer); newState is the new state of the algorithm.
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/.type1encrypt
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{ { exch pop } .type1crypt
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} bind def
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% <state> <fromString> <toString> .type1decrypt <newState> <toSubstring>
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% Decrypts fromString according to the algorithm for Adobe
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% Type 1 fonts, writing the result into toString. Other
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% specifications are as for type1encrypt.
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/.type1decrypt
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{ { pop 2 index exch get } .type1crypt
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} bind def
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