/* $NetBSD: rndpool.c,v 1.8 1999/01/27 10:41:01 mrg Exp $ */ /*- * Copyright (c) 1997 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Michael Graff . This code uses ideas and * algorithms from the Linux driver written by Ted Ts'o. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include #include #include #include #include /* * The random pool "taps" */ #define TAP1 99 #define TAP2 59 #define TAP3 31 #define TAP4 9 #define TAP5 7 static inline void rndpool_add_one_word(rndpool_t *, u_int32_t); void rndpool_init(rp) rndpool_t *rp; { rp->cursor = RND_POOLWORDS - 1; rp->entropy = 0; rp->rotate = 0; } u_int32_t rndpool_get_entropy_count(rp) rndpool_t *rp; { return rp->entropy; } void rndpool_set_entropy_count(rp, entropy) rndpool_t *rp; u_int32_t entropy; { rp->entropy = entropy; if (rp->entropy > RND_POOLBITS) rp->entropy = RND_POOLBITS; } void rndpool_increment_entropy_count(rp, entropy) rndpool_t *rp; u_int32_t entropy; { rp->entropy += entropy; if (rp->entropy > RND_POOLBITS) rp->entropy = RND_POOLBITS; } u_int32_t * rndpool_get_pool(rp) rndpool_t *rp; { return (rp->pool); } u_int32_t rndpool_get_poolsize(void) { return (RND_POOLWORDS); } /* * Add one word to the pool, rotating the input as needed. */ static inline void rndpool_add_one_word(rp, val) rndpool_t *rp; u_int32_t val; { /* * Steal some values out of the pool, and xor them into the * word we were given. * * Store the new value into the pool using xor. This will * prevent the actual values from being known to the caller * since the previous values are assumed to be unknown as well. */ val ^= rp->pool[(rp->cursor + TAP1) & (RND_POOLWORDS - 1)]; val ^= rp->pool[(rp->cursor + TAP2) & (RND_POOLWORDS - 1)]; val ^= rp->pool[(rp->cursor + TAP3) & (RND_POOLWORDS - 1)]; val ^= rp->pool[(rp->cursor + TAP4) & (RND_POOLWORDS - 1)]; val ^= rp->pool[(rp->cursor + TAP5) & (RND_POOLWORDS - 1)]; rp->pool[rp->cursor++] ^= ((val << rp->rotate) | (val >> (31 - rp->rotate))); /* * If we have looped around the pool, increment the rotate * variable so the next value will get xored in slightly * rotated. Increment by a value that is relativly prime to * the word size to try to spread the bits throughout the pool * quickly when the pool is empty. */ if (rp->cursor == RND_POOLWORDS) { rp->cursor = 0; rp->rotate = (rp->rotate + 7) & 31; } } /* * Add one byte to the pool. Update entropy estimate if an estimate * was given. */ void rndpool_add_uint32(rp, val, entropy) rndpool_t *rp; u_int32_t val; u_int32_t entropy; { val = (val << rp->rotate) | (val >> rp->rotate); rp->rotate = (rp->rotate + 1) & 0x07; rndpool_add_one_word(rp, val); if (entropy) { rp->entropy += entropy; if (rp->entropy > RND_POOLBITS) rp->entropy = RND_POOLBITS; } } /* * add a buffer's worth of data to the pool. */ void rndpool_add_data(rp, p, len, entropy) rndpool_t *rp; void *p; u_int32_t len; u_int32_t entropy; { u_int32_t val; u_int8_t *buf; buf = p; for (; len > 3 ; len -= 4) { val = *((u_int32_t *)buf); rndpool_add_one_word(rp, val); buf += 4; } val = 0; if (len != 0) { switch (len) { case 3: val = *buf++; case 2: val = val << 8 | *buf++; case 1: val = val << 8 | *buf++; } rndpool_add_one_word(rp, val); } if (entropy) { rp->entropy += entropy; if (rp->entropy > RND_POOLBITS) rp->entropy = RND_POOLBITS; } } /* * Extract some number of bytes from the random pool, decreasing the * estimate of randomness as each byte is extracted. * * Do this by stiring the pool and returning a part of hash as randomness. * Note that no secrets are given away here since parts of the hash are * xored together before returned. * * Honor the request from the caller to only return good data, any data, * etc. Note that we must have at least 64 bits of entropy in the pool * before we return anything in the high-quality modes. */ int rndpool_extract_data(rp, p, len, mode) rndpool_t *rp; void *p; u_int32_t len; u_int32_t mode; { u_int i; SHA1_CTX hash; u_int32_t digest[5]; u_int32_t remain; u_int8_t *buf; int good; buf = p; remain = len; if (mode == RND_EXTRACT_ANY) good = 1; else good = (rp->entropy >= 8 * RND_ENTROPY_THRESHOLD); /* * While bytes are requested, stir the pool with a hash function and * copy some of the bytes from that hash out, preserving the secret * hash value itself. */ while (good && (remain != 0)) { SHA1Init(&hash); SHA1Update(&hash, (u_int8_t *)rp->pool, RND_POOLWORDS * 4); SHA1Final((u_int8_t *)digest, &hash); /* * Add the hash into the pool. This helps stir the pool a * bit, and also guarantees that the next hash will generate * a different value if no new values were added to the * pool. */ for (i = 0 ; i < 5 ; i++) rndpool_add_one_word(rp, digest[i]); if (remain < RND_ENTROPY_THRESHOLD) { bcopy(digest, buf, remain); buf += remain; if (rp->entropy >= remain * 8) rp->entropy -= remain * 8; else rp->entropy = 0; remain = 0; } else { bcopy(digest, buf, RND_ENTROPY_THRESHOLD); buf += RND_ENTROPY_THRESHOLD; remain -= RND_ENTROPY_THRESHOLD; if (rp->entropy >= 8 * RND_ENTROPY_THRESHOLD) rp->entropy -= 8 * RND_ENTROPY_THRESHOLD; else rp->entropy = 0; } if (mode == RND_EXTRACT_GOOD) good = (rp->entropy >= 8 * RND_ENTROPY_THRESHOLD); } bzero(&hash, sizeof(hash)); bzero(digest, sizeof(digest)); return (len - remain); }