118 lines
2.3 KiB
C
118 lines
2.3 KiB
C
/*
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* This file Copyright (C) 2007-2014 Mnemosyne LLC
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*
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* It may be used under the GNU GPL versions 2 or 3
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* or any future license endorsed by Mnemosyne LLC.
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*
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* $Id$
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*/
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#include <assert.h>
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#include <stdarg.h>
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#include <stdlib.h> /* abs (), srand (), rand () */
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#include <string.h> /* memmove (), memset () */
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#include "transmission.h"
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#include "crypto-utils.h"
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#include "utils.h"
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/***
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****
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***/
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void
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tr_dh_align_key (uint8_t * key_buffer,
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size_t key_size,
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size_t buffer_size)
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{
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assert (key_size <= buffer_size);
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/* DH can generate key sizes that are smaller than the size of
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key buffer with exponentially decreasing probability, in which case
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the msb's of key buffer need to be zeroed appropriately. */
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if (key_size < buffer_size)
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{
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const size_t offset = buffer_size - key_size;
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memmove (key_buffer + offset, key_buffer, key_size);
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memset (key_buffer, 0, offset);
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}
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}
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/***
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****
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***/
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bool
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tr_sha1 (uint8_t * hash,
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const void * data1,
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int data1_length,
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...)
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{
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tr_sha1_ctx_t sha;
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if ((sha = tr_sha1_init ()) == NULL)
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return false;
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if (tr_sha1_update (sha, data1, data1_length))
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{
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va_list vl;
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const void * data;
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va_start (vl, data1_length);
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while ((data = va_arg (vl, const void *)) != NULL)
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{
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const int data_length = va_arg (vl, int);
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assert (data_length >= 0);
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if (!tr_sha1_update (sha, data, data_length))
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break;
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}
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va_end (vl);
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/* did we reach the end of argument list? */
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if (data == NULL)
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return tr_sha1_final (sha, hash);
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}
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tr_sha1_final (sha, NULL);
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return false;
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}
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/***
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****
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***/
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int
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tr_rand_int (int upper_bound)
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{
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int noise;
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assert (upper_bound > 0);
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while (tr_rand_buffer (&noise, sizeof (noise)))
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{
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noise = abs(noise) % upper_bound;
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/* abs(INT_MIN) is undefined and could return negative value */
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if (noise >= 0)
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return noise;
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}
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/* fall back to a weaker implementation... */
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return tr_rand_int_weak (upper_bound);
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}
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int
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tr_rand_int_weak (int upper_bound)
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{
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static bool init = false;
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assert (upper_bound > 0);
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if (!init)
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{
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srand (tr_time_msec ());
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init = true;
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}
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return rand () % upper_bound;
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}
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