ref: 375ad2d3abef711985c51eea140281a092c34d49
dir: /sys/lib/ghostscript/type1enc.ps/
% Copyright (C) 1992, 1993 Aladdin Enterprises. All rights reserved.
%
% This software is provided AS-IS with no warranty, either express or
% implied.
%
% This software is distributed under license and may not be copied,
% modified or distributed except as expressly authorized under the terms
% of the license contained in the file LICENSE in this distribution.
%
% For more information about licensing, please refer to
% http://www.ghostscript.com/licensing/. For information on
% commercial licensing, go to http://www.artifex.com/licensing/ or
% contact Artifex Software, Inc., 101 Lucas Valley Road #110,
% San Rafael, CA 94903, U.S.A., +1(415)492-9861.
% $Id: type1enc.ps,v 1.4 2002/02/21 21:49:28 giles Exp $
% type1enc.ps
% PostScript language versions of the Type 1 encryption/decryption algorithms.
% This file is normally not needed with Ghostscript, since Ghostscript
% implements these algorithms in C. For the specifications, see Chapter 7 of
% "Adobe Type 1 Font Format," ISBN 0-201-57044-0, published by Addison-Wesley.
/.type1crypt % <R> <from> <to> <proc> .type1crypt <R'> <to>
% (auxiliary procedure)
{ 4 1 roll
0 2 index length getinterval
0 1 2 index length 1 sub
{ % Stack: proc R from to index
2 index 1 index get % proc R from to index C/P
4 index -8 bitshift xor 3 copy put % proc R from to index P/C
5 index exec % proc R from to C
% Compute R' = ((R + C) * 52845 + 22719) mod 65536
% without exceeding a 31-bit integer magnitude, given that
% 0 <= R <= 65535 and 0 <= C <= 255.
4 -1 roll add
dup 20077 mul % 52845 - 32768
exch 1 and 15 bitshift add % only care about 16 low-order bits
22719 add 65535 and 3 1 roll
}
for exch pop 3 -1 roll pop
} bind def
% <state> <fromString> <toString> .type1encrypt <newState> <toSubstring>
% Encrypts fromString according to the algorithm for Adobe
% Type 1 fonts, writing the result into toString.
% toString must be at least as long as fromString or a
% rangecheck error occurs. state is the initial state of
% the encryption algorithm (a 16-bit non-negative
% integer); newState is the new state of the algorithm.
/.type1encrypt
{ { exch pop } .type1crypt
} bind def
% <state> <fromString> <toString> .type1decrypt <newState> <toSubstring>
% Decrypts fromString according to the algorithm for Adobe
% Type 1 fonts, writing the result into toString. Other
% specifications are as for type1encrypt.
/.type1decrypt
{ { pop 2 index exch get } .type1crypt
} bind def