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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 |
