/* * random_machdep.c -- A strong random number generator * * $Id: random_machdep.c,v 1.4 1995/12/29 08:04:32 markm Exp $ * * Version 0.95, last modified 18-Oct-95 * * Copyright Theodore Ts'o, 1994, 1995. All rights reserved. * * 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, and the entire permission notice in its entirety, * including the disclaimer of warranties. * 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. The name of the author may not be used to endorse or promote * products derived from this software without specific prior * written permission. * * ALTERNATIVELY, this product may be distributed under the terms of * the GNU Public License, in which case the provisions of the GPL are * required INSTEAD OF the above restrictions. (This clause is * necessary due to a potential bad interaction between the GPL and * the restrictions contained in a BSD-style copyright.) * * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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. */ #define MAX_BLKDEV 4 #include #include #include #include #include #include #include #include /* * The pool is stirred with a primitive polynomial of degree 128 * over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1. * For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1. */ #define POOLWORDS 128 /* Power of 2 - note that this is 32-bit words */ #define POOLBITS (POOLWORDS*32) #if POOLWORDS == 128 #define TAP1 99 /* The polynomial taps */ #define TAP2 59 #define TAP3 31 #define TAP4 9 #define TAP5 7 #elif POOLWORDS == 64 #define TAP1 62 /* The polynomial taps */ #define TAP2 38 #define TAP3 10 #define TAP4 6 #define TAP5 1 #else #error No primitive polynomial available for chosen POOLWORDS #endif #define WRITEBUFFER 512 /* size in bytes */ /* There is actually only one of these, globally. */ struct random_bucket { u_int add_ptr; u_int entropy_count; int input_rotate; u_int32_t *pool; }; /* There is one of these per entropy source */ struct timer_rand_state { u_long last_time; int last_delta; int nbits; }; static struct random_bucket random_state; static u_int32_t random_pool[POOLWORDS]; static struct timer_rand_state keyboard_timer_state; static struct timer_rand_state extract_timer_state; static struct timer_rand_state irq_timer_state[ICU_LEN]; static struct timer_rand_state blkdev_timer_state[MAX_BLKDEV]; static struct wait_queue *random_wait; inthand2_t *sec_intr_handler[ICU_LEN]; int sec_intr_unit[ICU_LEN]; #ifndef MIN #define MIN(a,b) (((a) < (b)) ? (a) : (b)) #endif void rand_initialize(void) { random_state.add_ptr = 0; random_state.entropy_count = 0; random_state.pool = random_pool; random_wait = NULL; } /* * This function adds an int into the entropy "pool". It does not * update the entropy estimate. The caller must do this if appropriate. * * The pool is stirred with a primitive polynomial of degree 128 * over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1. * For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1. * * We rotate the input word by a changing number of bits, to help * assure that all bits in the entropy get toggled. Otherwise, if we * consistently feed the entropy pool small numbers (like ticks and * scancodes, for example), the upper bits of the entropy pool don't * get affected. --- TYT, 10/11/95 */ static inline void add_entropy_word(struct random_bucket *r, const u_int32_t input) { u_int i; u_int32_t w; w = (input << r->input_rotate) | (input >> (32 - r->input_rotate)); i = r->add_ptr = (r->add_ptr - 1) & (POOLWORDS-1); if (i) r->input_rotate = (r->input_rotate + 7) & 31; else /* * At the beginning of the pool, add an extra 7 bits * rotation, so that successive passes spread the * input bits across the pool evenly. */ r->input_rotate = (r->input_rotate + 14) & 31; /* XOR in the various taps */ w ^= r->pool[(i+TAP1)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP2)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP3)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP4)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP5)&(POOLWORDS-1)]; w ^= r->pool[i]; /* Rotate w left 1 bit (stolen from SHA) and store */ r->pool[i] = (w << 1) | (w >> 31); } /* * This function adds entropy to the entropy "pool" by using timing * delays. It uses the timer_rand_state structure to make an estimate * of how any bits of entropy this call has added to the pool. * * The number "num" is also added to the pool - it should somehow describe * the type of event which just happened. This is currently 0-255 for * keyboard scan codes, and 256 upwards for interrupts. * On the i386, this is assumed to be at most 16 bits, and the high bits * are used for a high-resolution timer. */ static void add_timer_randomness(struct random_bucket *r, struct timer_rand_state *state, u_int num) { int delta, delta2; u_int nbits; u_int32_t time; #if defined(I586_CPU) || defined(I686_CPU) if (i586_ctr_rate != 0) { u_long low, high; /* RDTSC. */ __asm __volatile(".byte 0x0f,0x31" :"=a" (low), "=d" (high)); num ^= low << 16; r->entropy_count += 2; } else { #endif disable_intr(); outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH); num ^= inb(TIMER_CNTR0) << 16; num ^= inb(TIMER_CNTR0) << 24; enable_intr(); r->entropy_count += 2; #if defined(I586_CPU) || defined(I686_CPU) } #endif time = ticks; add_entropy_word(r, (u_int32_t) num); add_entropy_word(r, time); /* * Calculate number of bits of randomness we probably * added. We take into account the first and second order * deltas in order to make our estimate. */ delta = time - state->last_time; state->last_time = time; delta2 = delta - state->last_delta; state->last_delta = delta; if (delta < 0) delta = -delta; if (delta2 < 0) delta2 = -delta2; delta = MIN(delta, delta2) >> 1; for (nbits = 0; delta; nbits++) delta >>= 1; r->entropy_count += nbits; /* Prevent overflow */ if (r->entropy_count > POOLBITS) r->entropy_count = POOLBITS; } void add_keyboard_randomness(u_char scancode) { add_timer_randomness(&random_state, &keyboard_timer_state, scancode); } void add_interrupt_randomness(int irq) { (sec_intr_handler[irq])(sec_intr_unit[irq]); add_timer_randomness(&random_state, &irq_timer_state[irq], irq); } #ifdef notused void add_blkdev_randomness(int major) { if (major >= MAX_BLKDEV) return; add_timer_randomness(&random_state, &blkdev_timer_state[major], 0x200+major); } #endif /* notused */ /* * MD5 transform algorithm, taken from code written by Colin Plumb, * and put into the public domain * * QUESTION: Replace this with SHA, which as generally received better * reviews from the cryptographic community? */ /* The four core functions - F1 is optimized somewhat */ /* #define F1(x, y, z) (x & y | ~x & z) */ #define F1(x, y, z) (z ^ (x & (y ^ z))) #define F2(x, y, z) F1(z, x, y) #define F3(x, y, z) (x ^ y ^ z) #define F4(x, y, z) (y ^ (x | ~z)) /* This is the central step in the MD5 algorithm. */ #define MD5STEP(f, w, x, y, z, data, s) \ ( w += f(x, y, z) + data, w = w<>(32-s), w += x ) /* * The core of the MD5 algorithm, this alters an existing MD5 hash to * reflect the addition of 16 longwords of new data. MD5Update blocks * the data and converts bytes into longwords for this routine. */ static void MD5Transform(u_int32_t buf[4], u_int32_t const in[16]) { u_int32_t a, b, c, d; a = buf[0]; b = buf[1]; c = buf[2]; d = buf[3]; MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478, 7); MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12); MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17); MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22); MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf, 7); MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12); MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17); MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22); MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8, 7); MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12); MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17); MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22); MD5STEP(F1, a, b, c, d, in[12]+0x6b901122, 7); MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12); MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17); MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22); MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562, 5); MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340, 9); MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14); MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20); MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d, 5); MD5STEP(F2, d, a, b, c, in[10]+0x02441453, 9); MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14); MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20); MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6, 5); MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6, 9); MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14); MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20); MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905, 5); MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8, 9); MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14); MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20); MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942, 4); MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11); MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16); MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23); MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44, 4); MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11); MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16); MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23); MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6, 4); MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11); MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16); MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23); MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039, 4); MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11); MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16); MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23); MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244, 6); MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10); MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15); MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21); MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3, 6); MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10); MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15); MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21); MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f, 6); MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10); MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15); MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21); MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82, 6); MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10); MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15); MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21); buf[0] += a; buf[1] += b; buf[2] += c; buf[3] += d; } #undef F1 #undef F2 #undef F3 #undef F4 #undef MD5STEP #if POOLWORDS % 16 #error extract_entropy() assumes that POOLWORDS is a multiple of 16 words. #endif /* * This function extracts randomness from the "entropy pool", and * returns it in a buffer. This function computes how many remaining * bits of entropy are left in the pool, but it does not restrict the * number of bytes that are actually obtained. */ static inline int extract_entropy(struct random_bucket *r, char *buf, int nbytes) { int ret, i; u_int32_t tmp[4]; add_timer_randomness(r, &extract_timer_state, nbytes); /* Redundant, but just in case... */ if (r->entropy_count > POOLBITS) r->entropy_count = POOLBITS; /* Why is this here? Left in from Ted Ts'o. Perhaps to limit time. */ if (nbytes > 32768) nbytes = 32768; ret = nbytes; if (r->entropy_count / 8 >= nbytes) r->entropy_count -= nbytes*8; else r->entropy_count = 0; while (nbytes) { /* Hash the pool to get the output */ tmp[0] = 0x67452301; tmp[1] = 0xefcdab89; tmp[2] = 0x98badcfe; tmp[3] = 0x10325476; for (i = 0; i < POOLWORDS; i += 16) MD5Transform(tmp, r->pool+i); /* Modify pool so next hash will produce different results */ add_entropy_word(r, tmp[0]); add_entropy_word(r, tmp[1]); add_entropy_word(r, tmp[2]); add_entropy_word(r, tmp[3]); /* * Run the MD5 Transform one more time, since we want * to add at least minimal obscuring of the inputs to * add_entropy_word(). --- TYT */ MD5Transform(tmp, r->pool); /* Copy data to destination buffer */ i = MIN(nbytes, 16); memcpy(buf, (u_int8_t const *)tmp, i); nbytes -= i; buf += i; } /* Wipe data from memory */ bzero(tmp, sizeof(tmp)); return ret; } #ifdef notused /* XXX NOT the exported kernel interface */ /* * This function is the exported kernel interface. It returns some * number of good random numbers, suitable for seeding TCP sequence * numbers, etc. */ void get_random_bytes(void *buf, u_int nbytes) { extract_entropy(&random_state, (char *) buf, nbytes); } #endif /* notused */ u_int read_random(char *buf, u_int nbytes) { if ((nbytes * 8) > random_state.entropy_count) nbytes = random_state.entropy_count / 8; return extract_entropy(&random_state, buf, nbytes); } u_int read_random_unlimited(char *buf, u_int nbytes) { return extract_entropy(&random_state, buf, nbytes); } #ifdef notused u_int write_random(const char *buf, u_int nbytes) { u_int i; u_int32_t word, *p; for (i = nbytes, p = (u_int32_t *)buf; i >= sizeof(u_int32_t); i-= sizeof(u_int32_t), p++) add_entropy_word(&random_state, *p); if (i) { word = 0; memcpy(&word, p, i); add_entropy_word(&random_state, word); } return nbytes; } #endif /* notused */