lib/isc/entropy.c

18 /* $Id: entropy.c,v 1.22 2010/08/10 23:48:19 tbox Exp $ */
22  * This is the system independent part of the entropy module.  It is
24  * \link unix/entropy.c unix/entropy.c \endlink or win32/entropy.c.
35 #include <isc/entropy.h>
62  * Size of entropy pool in 32-bit words.  This _MUST_ be a power of 2.
94 	isc_uint32_t	entropy;	/*%< current entropy estimate in bits */
144 	isc_uint32_t	total;		/*%< entropy from this source */
223  * Add in entropy, even when the value we're adding in could be
227 add_entropy(isc_entropy_t *ent, isc_uint32_t entropy) {
229 	entropy = ISC_MIN(entropy, RND_POOLBITS);
230 	/* Add in the entropy we already have. */
231 	entropy += ent->pool.entropy;
233 	ent->pool.entropy = ISC_MIN(entropy, RND_POOLBITS);
237  * Decrement the amount of entropy the pool has.
240 subtract_entropy(isc_entropy_t *ent, isc_uint32_t entropy) {
241 	entropy = ISC_MIN(entropy, ent->pool.entropy);
242 	ent->pool.entropy -= entropy;
246  * Add in entropy, even when the value we're adding in could be
309  * Requires that the lock is held on the entropy pool.
313 		    isc_uint32_t entropy)
360 	add_entropy(ent, entropy);
361 	subtract_pseudo(ent, entropy);
424 	 * If any delta is 0, we got no entropy.  If all are non-zero, we
571 			 * of entropy in the pool, don't block here.  It is
576 			if (ent->pool.entropy >= THRESHOLD_BITS)
582 			 * Verify that we got enough entropy to do one
585 			if (ent->pool.entropy < THRESHOLD_BITS) {
626 		deltae = ISC_MIN(deltae, ent->pool.entropy);
643 	/* put the entropy we almost extracted back */
658 	pool->entropy = 0;
667 	pool->entropy = 0;
904 	 * Hook it into the entropy system.
983 	 * Hook it into the entropy system.
1028 	unsigned int entropy;
1040 		entropy = crunchsamples(ent, sq);
1041 		add_entropy(ent, entropy);
1067 		    isc_uint32_t entropy)
1073 	entropypool_adddata(ent, data, length, entropy);
1087 			       " rotate %u entropy %u pseudo %u nsources %u"
1091 		ent->pool.entropy, ent->pool.pseudo,
1113 	estimate = ent->pool.entropy;
1159 	 * entropy multiple times.
1171 				"entropy, since your system is lacking\n"
1271 	 * final_result is ISC_R_SUCCESS if at least one source of entropy