49 lines
1.3 KiB
OCaml
49 lines
1.3 KiB
OCaml
(* A CBC abstraction layer
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Copyright (C) 2008 Michael Bacarella <mbac@panix.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*)
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type state =
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{
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mutable prev_v: string;
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}
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let init iv =
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{
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prev_v = iv;
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}
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let xor_strings b c =
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let int c = int_of_char c in
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String.init (String.length b)
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(fun i ->
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char_of_int @@
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int b.[i] lxor int c.[i])
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let encrypt cbc enc p =
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assert (String.length p = Primitive.key_ize);
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let p' = xor_strings p cbc.prev_v in
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let c = enc p' in
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(cbc.prev_v <- c; c)
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let decrypt cbc dec c =
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assert (String.length p = Primitive.key_ize);
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let p = dec c in
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let p' = xor_strings p cbc.prev_v in
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(cbc.prev_v <- c; p')
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