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% Copyright (C) 1992, 1993 Aladdin Enterprises. All rights reserved.
%
% This file is part of Aladdin Ghostscript.
%
% Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND. No author
% or distributor accepts any responsibility for the consequences of using it,
% or for whether it serves any particular purpose or works at all, unless he
% or she says so in writing. Refer to the Aladdin Ghostscript Free Public
% License (the "License") for full details.
%
% Every copy of Aladdin Ghostscript must include a copy of the License,
% normally in a plain ASCII text file named PUBLIC. The License grants you
% the right to copy, modify and redistribute Aladdin Ghostscript, but only
% under certain conditions described in the License. Among other things, the
% License requires that the copyright notice and this notice be preserved on
% all copies.
% 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
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