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/*
* purple
*
* Purple is the legal property of its developers, whose names are too numerous
* to list here. Please refer to the COPYRIGHT file distributed with this
* source distribution.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1301 USA
*/
#include <cipher.h>
#include <util.h>
struct RC4Context {
guchar state[256];
guchar x;
guchar y;
gint key_len;
};
static void
rc4_init(PurpleCipherContext *context, void *extra) {
struct RC4Context *rc4_ctx;
rc4_ctx = g_new0(struct RC4Context, 1);
purple_cipher_context_set_data(context, rc4_ctx);
purple_cipher_context_reset(context, extra);
}
static void
rc4_reset(PurpleCipherContext *context, void *extra) {
struct RC4Context *rc4_ctx;
guint i;
rc4_ctx = purple_cipher_context_get_data(context);
g_return_if_fail(rc4_ctx);
for(i = 0; i < 256; i++)
rc4_ctx->state[i] = i;
rc4_ctx->x = 0;
rc4_ctx->y = 0;
/* default is 5 bytes (40bit key) */
rc4_ctx->key_len = 5;
}
static void
rc4_uninit(PurpleCipherContext *context) {
struct RC4Context *rc4_ctx;
rc4_ctx = purple_cipher_context_get_data(context);
memset(rc4_ctx, 0, sizeof(*rc4_ctx));
g_free(rc4_ctx);
rc4_ctx = NULL;
}
static void
rc4_set_key (PurpleCipherContext *context, const guchar * key) {
struct RC4Context *ctx;
guchar *state;
guchar temp_swap;
guchar x, y;
guint i;
ctx = purple_cipher_context_get_data(context);
x = 0;
y = 0;
state = &ctx->state[0];
for(i = 0; i < 256; i++)
{
y = (key[x] + state[i] + y) % 256;
temp_swap = state[i];
state[i] = state[y];
state[y] = temp_swap;
x = (x + 1) % ctx->key_len;
}
}
static void
rc4_set_opt(PurpleCipherContext *context, const gchar *name, void *value) {
struct RC4Context *ctx;
ctx = purple_cipher_context_get_data(context);
if(purple_strequal(name, "key_len")) {
ctx->key_len = GPOINTER_TO_INT(value);
}
}
static size_t
rc4_get_key_size (PurpleCipherContext *context)
{
struct RC4Context *ctx;
g_return_val_if_fail(context, -1);
ctx = purple_cipher_context_get_data(context);
g_return_val_if_fail(ctx, -1);
return ctx->key_len;
}
static void *
rc4_get_opt(PurpleCipherContext *context, const gchar *name) {
struct RC4Context *ctx;
ctx = purple_cipher_context_get_data(context);
if(purple_strequal(name, "key_len")) {
return GINT_TO_POINTER(ctx->key_len);
}
return NULL;
}
static gint
rc4_encrypt(PurpleCipherContext *context, const guchar data[],
size_t len, guchar output[], size_t *outlen) {
struct RC4Context *ctx;
guchar temp_swap;
guchar x, y, z;
guchar *state;
guint i;
ctx = purple_cipher_context_get_data(context);
x = ctx->x;
y = ctx->y;
state = &ctx->state[0];
for(i = 0; i < len; i++)
{
x = (x + 1) % 256;
y = (state[x] + y) % 256;
temp_swap = state[x];
state[x] = state[y];
state[y] = temp_swap;
z = state[x] + (state[y]) % 256;
output[i] = data[i] ^ state[z];
}
ctx->x = x;
ctx->y = y;
if(outlen)
*outlen = len;
return 0;
}
static PurpleCipherOps RC4Ops = {
rc4_set_opt, /* Set Option */
rc4_get_opt, /* Get Option */
rc4_init, /* init */
rc4_reset, /* reset */
rc4_uninit, /* uninit */
NULL, /* set iv */
NULL, /* append */
NULL, /* digest */
rc4_encrypt, /* encrypt */
NULL, /* decrypt */
NULL, /* set salt */
NULL, /* get salt size */
rc4_set_key, /* set key */
rc4_get_key_size, /* get key size */
NULL, /* set batch mode */
NULL, /* get batch mode */
NULL, /* get block size */
NULL /* set key with len */
};
PurpleCipherOps *
purple_rc4_cipher_get_ops(void) {
return &RC4Ops;
}
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