annotate rng_make_prng.c @ 16:09ab3354aa21 libtomcrypt

propagate of e8bea23df30f9f46c647d06db3b223427b4e3604 and b0b6b4a8843b94d9f049cb5ffe0b1ae91ec1bf8b from branch 'au.asn.ucc.matt.ltc-orig' to 'au.asn.ucc.matt.ltc-db'
author Matt Johnston <matt@ucc.asn.au>
date Tue, 15 Jun 2004 14:27:14 +0000
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 *
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9 * Tom St Denis, [email protected], http://libtomcrypt.org
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10 */
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11 /* portable way to get secure random bits to feed a PRNG */
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12 #include "mycrypt.h"
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13
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14 int rng_make_prng(int bits, int wprng, prng_state *prng,
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15 void (*callback)(void))
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16 {
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17 unsigned char buf[256];
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18 int err;
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19
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20 _ARGCHK(prng != NULL);
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21
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22 /* check parameter */
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23 if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
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24 return err;
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25 }
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26
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27 if (bits < 64 || bits > 1024) {
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28 return CRYPT_INVALID_PRNGSIZE;
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29 }
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30
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31 if ((err = prng_descriptor[wprng].start(prng)) != CRYPT_OK) {
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32 return err;
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33 }
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34
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35 bits = ((bits/8)+((bits&7)!=0?1:0)) * 2;
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36 if (rng_get_bytes(buf, (unsigned long)bits, callback) != (unsigned long)bits) {
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37 return CRYPT_ERROR_READPRNG;
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38 }
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39
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40 if ((err = prng_descriptor[wprng].add_entropy(buf, (unsigned long)bits, prng)) != CRYPT_OK) {
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41 return err;
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42 }
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43
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44 if ((err = prng_descriptor[wprng].ready(prng)) != CRYPT_OK) {
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45 return err;
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46 }
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47
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48 #ifdef CLEAN_STACK
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49 zeromem(buf, sizeof(buf));
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50 #endif
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51 return CRYPT_OK;
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52 }
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53