forked from osmocom/wireshark
71 lines
1.8 KiB
C
71 lines
1.8 KiB
C
/* xtea.c
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* Implementation of XTEA cipher
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* By Ahmad Fatoum <ahmad[AT]a3f.at>
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* Copyright 2017 Ahmad Fatoum
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include <glib.h>
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#include <string.h>
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#include "pint.h"
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#include "xtea.h"
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void decrypt_xtea_ecb(guint8 plaintext[8], const guint8 ciphertext[8], const guint32 key[4], guint num_rounds)
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{
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guint i;
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guint32 v[2], delta = 0x9E3779B9, sum = delta * num_rounds;
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v[0] = pntoh32(&ciphertext[0]);
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v[1] = pntoh32(&ciphertext[4]);
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for (i = 0; i < num_rounds; i++) {
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v[1] -= (((v[0] << 4) ^ (v[0] >> 5)) + v[0]) ^ (sum + key[(sum >> 11) & 3]);
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sum -= delta;
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v[0] -= (((v[1] << 4) ^ (v[1] >> 5)) + v[1]) ^ (sum + key[sum & 3]);
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}
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v[0] = GUINT32_TO_BE(v[0]);
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v[1] = GUINT32_TO_BE(v[1]);
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memcpy(plaintext, v, sizeof v);
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}
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void decrypt_xtea_le_ecb(guint8 plaintext[8], const guint8 ciphertext[8], const guint32 key[4], guint num_rounds)
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{
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guint i;
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guint32 v[2], delta = 0x9E3779B9, sum = delta * num_rounds;
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v[0] = pletoh32(&ciphertext[0]);
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v[1] = pletoh32(&ciphertext[4]);
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for (i = 0; i < num_rounds; i++) {
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v[1] -= (((v[0] << 4) ^ (v[0] >> 5)) + v[0]) ^ (sum + key[(sum >> 11) & 3]);
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sum -= delta;
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v[0] -= (((v[1] << 4) ^ (v[1] >> 5)) + v[1]) ^ (sum + key[sum & 3]);
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}
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v[0] = GUINT32_TO_LE(v[0]);
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v[1] = GUINT32_TO_LE(v[1]);
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memcpy(plaintext, v, sizeof v);
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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