annotate src/prngs/rng_make_prng.c @ 195:19e5d79b7190 libtomcrypt

Cleanup of import of LTC 1.02, still problematic for Dropbear
author Matt Johnston <matt@ucc.asn.au>
date Mon, 09 May 2005 09:33:00 +0000
parents 1c15b283127b
children 39d5d58461d6
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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 #include "tomcrypt.h"
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12
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13 /**
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14 @file rng_make_prng.c
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15 portable way to get secure random bits to feed a PRNG (Tom St Denis)
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16 */
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17
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18 /**
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19 Create a PRNG from a RNG
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20 @param bits Number of bits of entropy desired (64 ... 1024)
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21 @param wprng Index of which PRNG to setup
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22 @param prng [out] PRNG state to initialize
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23 @param callback A pointer to a void function for when the RNG is slow, this can be NULL
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24 @return CRYPT_OK if successful
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25 */
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26 int rng_make_prng(int bits, int wprng, prng_state *prng,
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27 void (*callback)(void))
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28 {
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29 unsigned char buf[256];
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30 int err;
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31
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32 LTC_ARGCHK(prng != NULL);
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33
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34 /* check parameter */
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35 if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
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36 return err;
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37 }
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38
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39 if (bits < 64 || bits > 1024) {
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40 return CRYPT_INVALID_PRNGSIZE;
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41 }
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42
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43 if ((err = prng_descriptor[wprng].start(prng)) != CRYPT_OK) {
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44 return err;
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45 }
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46
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47 bits = ((bits/8)+((bits&7)!=0?1:0)) * 2;
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48 if (rng_get_bytes(buf, (unsigned long)bits, callback) != (unsigned long)bits) {
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49 return CRYPT_ERROR_READPRNG;
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50 }
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51
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52 if ((err = prng_descriptor[wprng].add_entropy(buf, (unsigned long)bits, prng)) != CRYPT_OK) {
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53 return err;
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54 }
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55
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56 if ((err = prng_descriptor[wprng].ready(prng)) != CRYPT_OK) {
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57 return err;
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58 }
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59
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60 #ifdef LTC_CLEAN_STACK
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61 zeromem(buf, sizeof(buf));
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62 #endif
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63 return CRYPT_OK;
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64 }
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65