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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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* The library is free for all purposes without any express
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* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
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/* portable way to get secure random bits to feed a PRNG */
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int rng_make_prng(int bits, int wprng, prng_state *prng,
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void (*callback)(void))
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unsigned char buf[256];
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_ARGCHK(prng != NULL);
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if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
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if (bits < 64 || bits > 1024) {
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return CRYPT_INVALID_PRNGSIZE;
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if ((err = prng_descriptor[wprng].start(prng)) != CRYPT_OK) {
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bits = ((bits/8)+((bits&7)!=0?1:0)) * 2;
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if (rng_get_bytes(buf, (unsigned long)bits, callback) != (unsigned long)bits) {
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return CRYPT_ERROR_READPRNG;
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if ((err = prng_descriptor[wprng].add_entropy(buf, (unsigned long)bits, prng)) != CRYPT_OK) {
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if ((err = prng_descriptor[wprng].ready(prng)) != CRYPT_OK) {
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zeromem(buf, sizeof(buf));