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Diffstat (limited to 'contrib/bind/lib/dst/prandom.c')
-rw-r--r-- | contrib/bind/lib/dst/prandom.c | 851 |
1 files changed, 851 insertions, 0 deletions
diff --git a/contrib/bind/lib/dst/prandom.c b/contrib/bind/lib/dst/prandom.c new file mode 100644 index 000000000000..0a66e61512e4 --- /dev/null +++ b/contrib/bind/lib/dst/prandom.c @@ -0,0 +1,851 @@ +#ifndef LINT +static const char rcsid[] = "$Header: /proj/cvs/isc/bind/src/lib/dst/prandom.c,v 1.8 1999/10/13 16:39:24 vixie Exp $"; +#endif +/* + * Portions Copyright (c) 1995-1998 by Trusted Information Systems, Inc. + * + * Permission to use, copy modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND TRUSTED INFORMATION SYSTEMS + * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL + * TRUSTED INFORMATION SYSTEMS BE LIABLE FOR ANY SPECIAL, DIRECT, + * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING + * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, + * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION + * WITH THE USE OR PERFORMANCE OF THE SOFTWARE. + */ + +#include "port_before.h" + +#include <stdio.h> +#include <sys/types.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <fcntl.h> +#include <time.h> +#include <dirent.h> +#include <sys/param.h> +#include <sys/stat.h> +#include <sys/time.h> + +#include "dst_internal.h" +#include "prand_conf.h" + +#include "port_after.h" + +#ifndef DST_NUM_HASHES +#define DST_NUM_HASHES 4 +#endif +#ifndef DST_NUMBER_OF_COUNTERS +#define DST_NUMBER_OF_COUNTERS 5 /* 32 * 5 == 160 == SHA(1) > MD5 */ +#endif + +/* + * the constant below is a prime number to make fixed data structues like + * stat and time wrap over blocks. This adds certain uncertanty to what is + * in each digested block. + * The prime number 2879 has the special property that when + * divided by 2,4 and 6 the result is also a prime numbers + */ + +#ifndef DST_RANDOM_BLOCK_SIZE +#define DST_RANDOM_BLOCK_SIZE 2879 +#endif + +/* + * This constant dictatates how many bits we shift to the right before using a + */ +#ifndef DST_SHIFT +#define DST_SHIFT 9 +#endif + +/* + * An initalizer that is as bad as any other with half the bits set + */ +#ifndef DST_RANDOM_PATTERN +#define DST_RANDOM_PATTERN 0x8765CA93 +#endif +/* + * things must have changed in the last 3600 seconds to be used + */ +#define MAX_OLD 3600 + + +/* + * these two data structure are used to process input data into digests, + * + * The first structure is containts a pointer to a DST HMAC key + * the variables accompanying are used for + * step : select every step byte from input data for the hash + * block: number of data elements going into each hash + * digested: number of data elements digested so far + * curr: offset into the next input data for the first byte. + */ +typedef struct hash { + DST_KEY *key; + void *ctx; + int digested, block, step, curr; +} prand_hash; + +/* + * This data structure controlls number of hashes and keeps track of + * overall progress in generating correct number of bytes of output. + * output : array to store the output data in + * needed : how many bytes of output are needed + * filled : number of bytes in output so far. + * bytes : total number of bytes processed by this structure + * file_digest : the HMAC key used to digest files. + */ +typedef struct work { + int needed, filled, bytes; + u_char *output; + prand_hash *hash[DST_NUM_HASHES]; + DST_KEY *file_digest; +} dst_work; + + +/* + * forward function declarations + */ +static int get_dev_random(u_char *output, int size); +static int do_time(dst_work *work); +static int do_ls(dst_work *work); +static int unix_cmd(dst_work *work); +static int digest_file(dst_work *work); + +static void force_hash(dst_work *work, prand_hash *hash); +static int do_hash(dst_work *work, prand_hash *hash, u_char *input, + int size); +static int my_digest(dst_work *tmp, u_char *input, int size); +static prand_hash *get_hmac_key(int step, int block); + +static int own_random(dst_work *work); + + +/* + * variables used in the quick random number generator + */ +static u_int32_t ran_val = DST_RANDOM_PATTERN; +static u_int32_t ran_cnt = (DST_RANDOM_PATTERN >> 10); + +/* + * setting the quick_random generator to particular values or if both + * input parameters are 0 then set it to initial vlaues + */ + +void +dst_s_quick_random_set(u_int32_t val, u_int32_t cnt) +{ + ran_val = (val == 0) ? DST_RANDOM_PATTERN : val; + ran_cnt = (cnt == 0) ? (DST_RANDOM_PATTERN >> 10) : cnt; +} + +/* + * this is a quick and random number generator that seems to generate quite + * good distribution of data + */ +u_int32_t +dst_s_quick_random(int inc) +{ + ran_val = ((ran_val >> 13) ^ (ran_val << 19)) ^ + ((ran_val >> 7) ^ (ran_val << 25)); + if (inc > 0) /* only increasing values accepted */ + ran_cnt += inc; + ran_val += ran_cnt++; + return (ran_val); +} + +/* + * get_dev_random: Function to read /dev/random reliably + * this function returns how many bytes where read from the device. + * port_after.h should set the control variable HAVE_DEV_RANDOM + */ +static int +get_dev_random(u_char *output, int size) +{ +#ifdef HAVE_DEV_RANDOM + struct stat st; + int n = 0, fd = -1, s; + + s = stat("/dev/random", &st); + if (s == 0 && S_ISCHR(st.st_mode)) { + if ((fd = open("/dev/random", O_RDONLY | O_NONBLOCK)) != -1) { + if ((n = read(fd, output, size)) < 0) + n = 0; + close(fd); + } + return (n); + } +#endif + return (0); +} + +/* + * Portable way of getting the time values if gettimeofday is missing + * then compile with -DMISSING_GETTIMEOFDAY time() is POSIX compliant but + * gettimeofday() is not. + * Time of day is predictable, we are looking for the randomness that comes + * the last few bits in the microseconds in the timer are hard to predict when + * this is invoked at the end of other operations + */ +struct timeval *mtime; +static int +do_time(dst_work *work) +{ + int cnt = 0; + static u_char tmp[sizeof(struct timeval) + sizeof(struct timezone)]; + struct timezone *zone; + + zone = (struct timezone *) tmp; + mtime = (struct timeval *)(tmp + sizeof(struct timezone)); + gettimeofday(mtime, zone); + cnt = sizeof(tmp); + my_digest(work, tmp, sizeof(tmp)); + + return (cnt); +} + +/* + * this function simulates the ls command, but it uses stat which gives more + * information and is harder to guess + * Each call to this function will visit the next directory on the list of + * directories, in a circular manner. + * return value is the number of bytes added to the temp buffer + * + * do_ls() does not visit subdirectories + * if attacker has access to machine it can guess most of the values seen + * thus it is important to only visit directories that are freqently updated + * Attacker that has access to the network can see network traffic + * when NFS mounted directories are accessed and know exactly the data used + * but may not know exactly in what order data is used. + * Returns the number of bytes that where returned in stat structures + */ +static int +do_ls(dst_work *work) +{ + struct dir_info { + uid_t uid; + gid_t gid; + off_t size; + time_t atime, mtime, ctime; + }; + static struct dir_info dir_info; + struct stat buf; + struct dirent *entry; + static int i = 0; + static unsigned long d_round = 0; + struct timeval tv; + int n = 0, dir_len, tb_i = 0, out = 0; + + char file_name[1024]; + u_char tmp_buff[1024]; + DIR *dir = NULL; + + if (dirs[i] == NULL) /* if at the end of the list start over */ + i = 0; + if (stat(dirs[i++], &buf)) /* directory does not exist */ + return (0); + + gettimeofday(&tv,NULL); + if (d_round == 0) + d_round = tv.tv_sec - MAX_OLD; + else if (i==1) /* if starting a new round cut what we accept */ + d_round += (tv.tv_sec - d_round)/2; + + if (buf.st_atime < d_round) + return (0); + + EREPORT(("do_ls i %d filled %4d in_temp %4d\n", + i-1, work->filled, work->in_temp)); + memcpy(tmp_buff, &buf, sizeof(buf)); + tb_i += sizeof(buf); + + + if ((dir = opendir(dirs[i-1])) == NULL)/* open it for read */ + return (0); + strcpy(file_name, dirs[i-1]); + dir_len = strlen(file_name); + file_name[dir_len++] = '/'; + while ((entry = readdir(dir))) { + int len = strlen(entry->d_name); + out += len; + if (my_digest(work, (u_char *)entry->d_name, len)) + break; + + memcpy(&file_name[dir_len], entry->d_name, len); + file_name[dir_len + len] = 0x0; + /* for all entries in dir get the stats */ + if (stat(file_name, &buf) == 0) { + n++; /* count successfull stat calls */ + /* copy non static fields */ + dir_info.uid += buf.st_uid; + dir_info.gid += buf.st_gid; + dir_info.size += buf.st_size; + dir_info.atime += buf.st_atime; + dir_info.mtime += buf.st_mtime; + dir_info.ctime += buf.st_ctime; + out += sizeof(dir_info); + if(my_digest(work, (u_char *)&dir_info, + sizeof(dir_info))) + break; + } + } + closedir(dir); /* done */ + out += do_time(work); /* add a time stamp */ + return (out); +} + + +/* + * unix_cmd() + * this function executes the a command from the cmds[] list of unix commands + * configured in the prand_conf.h file + * return value is the number of bytes added to the randomness temp buffer + * + * it returns the number of bytes that where read in + * if more data is needed at the end time is added to the data. + * This function maintains a state to selects the next command to run + * returns the number of bytes read in from the command + */ +static int +unix_cmd(dst_work *work) +{ + static int cmd_index = 0; + int cnt = 0, n; + FILE *pipe; + u_char buffer[4096]; + + if (cmds[cmd_index] == NULL) + cmd_index = 0; + EREPORT(("unix_cmd() i %d filled %4d in_temp %4d\n", + cmd_index, work->filled, work->in_temp)); + pipe = popen(cmds[cmd_index++], "r"); /* execute the command */ + + while ((n = fread(buffer, sizeof(char), sizeof(buffer), pipe)) > 0) { + cnt += n; /* process the output */ + if (my_digest(work, buffer, n)) + break; + /* this adds some randomness to the output */ + cnt += do_time(work); + } + while ((n = fread(buffer, sizeof(char), sizeof(buffer), pipe)) > 0) + NULL; /* drain the pipe */ + pclose(pipe); + return (cnt); /* read how many bytes where read in */ +} + +/* + * digest_file() This function will read a file and run hash over it + * input is a file name + */ +static int +digest_file(dst_work *work) +{ + static int f_cnt = 0; + static unsigned long f_round = 0; + FILE *fp; + void *ctx; + const char *name; + int no, i; + struct stat st; + struct timeval tv; + u_char buf[1024]; + + if (f_round == 0 || files[f_cnt] == NULL || work->file_digest == NULL) + if (gettimeofday(&tv, NULL)) /* only do this if needed */ + return (0); + if (f_round == 0) /* first time called set to one hour ago */ + f_round = (tv.tv_sec - MAX_OLD); + name = files[f_cnt++]; + if (files[f_cnt] == NULL) { /* end of list of files */ + if(f_cnt <= 1) /* list is too short */ + return (0); + f_cnt = 0; /* start again on list */ + f_round += (tv.tv_sec - f_round)/2; /* set new cutoff */ + work->file_digest = dst_free_key(work->file_digest); + } + if (work->file_digest == NULL) { + work->file_digest = dst_buffer_to_key("", KEY_HMAC_MD5, 0, 0, + (u_char *)&tv, sizeof(tv)); + if (work->file_digest == NULL) + return (0); + } + if (access(name, R_OK) || stat(name, &st)) + return (0); /* no such file or not allowed to read it */ + if (strncmp(name, "/proc/", 6) && st.st_mtime < f_round) + return(0); /* file has not changed recently enough */ + if (dst_sign_data(SIG_MODE_INIT, work->file_digest, &ctx, + NULL, 0, NULL, 0)) { + work->file_digest = dst_free_key(work->file_digest); + return (0); + } + if ((fp = fopen(name, "r")) == NULL) + return (0); + for (no = 0; (i = fread(buf, sizeof(*buf), sizeof(buf), fp)) > 0; + no += i) + dst_sign_data(SIG_MODE_UPDATE, work->file_digest, &ctx, + buf, i, NULL, 0); + + fclose(fp); + if (no >= 64) { + i = dst_sign_data(SIG_MODE_FINAL, work->file_digest, &ctx, + NULL, 0, &work->output[work->filled], + DST_HASH_SIZE); + if (i > 0) + work->filled += i; + } + else if (i > 0) + my_digest(work, buf, i); + my_digest(work, (u_char *)name, strlen(name)); + return (no + strlen(name)); +} + +/* + * function to perform the FINAL and INIT operation on a hash if allowed + */ +static void +force_hash(dst_work *work, prand_hash *hash) +{ + int i = 0; + + /* + * if more than half a block then add data to output + * otherwise adde the digest to the next hash + */ + if ((hash->digested * 2) > hash->block) { + i = dst_sign_data(SIG_MODE_FINAL, hash->key, &hash->ctx, + NULL, 0, &work->output[work->filled], + DST_HASH_SIZE); + + hash->digested = 0; + dst_sign_data(SIG_MODE_INIT, hash->key, &hash->ctx, + NULL, 0, NULL, 0); + if (i > 0) + work->filled += i; + } + return; +} + +/* + * This function takes the input data does the selection of data specified + * by the hash control block. + * The step varialbe in the work sturcture determines which 1/step bytes + * are used, + * + */ +static int +do_hash(dst_work *work, prand_hash *hash, u_char *input, int size) +{ + u_char *tmp = input, *tp; + int i, cnt = size, n, needed, avail, dig, tmp_size = 0; + + if (cnt <= 0 || input == NULL) + return (0); + + if (hash->step > 1) { /* if using subset of input data */ + tmp_size = size / hash->step + 2; + tp = tmp = malloc(tmp_size); + for (cnt = 0, i = hash->curr; i < size; i += hash->step, cnt++) + *(tp++) = input[i]; + /* calcutate the starting point in the next input set */ + hash->curr = (hash->step - (i - size)) % hash->step; + } + /* digest the data in block sizes */ + for (n = 0; n < cnt; n += needed) { + avail = (cnt - n); + needed = hash->block - hash->digested; + dig = (avail < needed) ? avail : needed; + dst_sign_data(SIG_MODE_UPDATE, hash->key, &hash->ctx, + &tmp[n], dig, NULL, 0); + hash->digested += dig; + if (hash->digested >= hash->block) + force_hash(work, hash); + if (work->needed < work->filled) { + if (tmp != input) + SAFE_FREE2(tmp, tmp_size); + return (1); + } + } + if (tmp_size > 0) + SAFE_FREE2(tmp, tmp_size); + return (0); +} + +/* + * Copy data from INPUT for length SIZE into the work-block TMP. + * If we fill the work-block, digest it; then, + * if work-block needs more data, keep filling with the rest of the input. + */ +static int +my_digest(dst_work *work, u_char *input, int size) +{ + + int i, full = 0; + static unsigned counter; + + counter += size; + /* first do each one of the hashes */ + for (i = 0; i < DST_NUM_HASHES && full == 0; i++) + full = do_hash(work, work->hash[i], input, size) + + do_hash(work, work->hash[i], (u_char *) &counter, + sizeof(counter)); +/* + * if enough data has be generated do final operation on all hashes + * that have enough date for that + */ + for (i = 0; full && (i < DST_NUM_HASHES); i++) + force_hash(work, work->hash[i]); + + return (full); +} + +/* + * this function gets some semi random data and sets that as an HMAC key + * If we get a valid key this function returns that key initalized + * otherwise it returns NULL; + */ +static prand_hash * +get_hmac_key(int step, int block) +{ + + u_char *buff; + int temp = 0, n = 0, size = 70; + DST_KEY *new_key = NULL; + prand_hash *new = NULL; + + /* use key that is larger than digest algorithms (64) for key size */ + buff = malloc(size); + if (buff == NULL) + return (NULL); + /* do not memset the allocated memory to get random bytes there */ + /* time of day is somewhat random expecialy in the last bytes */ + gettimeofday((struct timeval *) &buff[n], NULL); + n += sizeof(struct timeval); + +/* get some semi random stuff in here stir it with micro seconds */ + if (n < size) { + temp = dst_s_quick_random((int) buff[n - 1]); + memcpy(&buff[n], &temp, sizeof(temp)); + n += sizeof(temp); + } +/* get the pid of this process and its parent */ + if (n < size) { + temp = (int) getpid(); + memcpy(&buff[n], &temp, sizeof(temp)); + n += sizeof(temp); + } + if (n < size) { + temp = (int) getppid(); + memcpy(&buff[n], &temp, sizeof(temp)); + n += sizeof(temp); + } +/* get the user ID */ + if (n < size) { + temp = (int) getuid(); + memcpy(&buff[n], &temp, sizeof(temp)); + n += sizeof(temp); + } +#ifndef GET_HOST_ID_MISSING + if (n < size) { + temp = (int) gethostid(); + memcpy(&buff[n], &temp, sizeof(temp)); + n += sizeof(temp); + } +#endif +/* get some more random data */ + if (n < size) { + temp = dst_s_quick_random((int) buff[n - 1]); + memcpy(&buff[n], &temp, sizeof(temp)); + n += sizeof(temp); + } +/* covert this into a HMAC key */ + new_key = dst_buffer_to_key("", KEY_HMAC_MD5, 0, 0, buff, size); + SAFE_FREE(buff); + +/* get the control structure */ + if ((new = malloc(sizeof(prand_hash))) == NULL) + return (NULL); + new->digested = new->curr = 0; + new->step = step; + new->block = block; + new->key = new_key; + if (dst_sign_data(SIG_MODE_INIT, new_key, &new->ctx, NULL, 0, NULL, 0)) + return (NULL); + + return (new); +} + +/* + * own_random() + * This function goes out and from various sources tries to generate enough + * semi random data that a hash function can generate a random data. + * This function will iterate between the two main random source sources, + * information from programs and directores in random order. + * This function return the number of bytes added to the random output buffer. + */ +static int +own_random(dst_work *work) +{ + int dir = 0, b; + int bytes, n, cmd = 0, dig = 0; + int start =0; +/* + * now get the initial seed to put into the quick random function from + * the address of the work structure + */ + bytes = (int) getpid(); +/* + * proceed while needed + */ + while (work->filled < work->needed) { + EREPORT(("own_random r %08x b %6d t %6d f %6d\n", + ran_val, bytes, work->in_temp, work->filled)); +/* pick a random number in the range of 0..7 based on that random number + * perform some operations that yield random data + */ + start = work->filled; + n = (dst_s_quick_random(bytes) >> DST_SHIFT) & 0x07; + switch (n) { + case 0: + case 3: + if (sizeof(cmds) > 2 *sizeof(*cmds)) { + b = unix_cmd(work); + cmd += b; + } + break; + + case 1: + case 7: + if (sizeof(dirs) > 2 *sizeof(*dirs)) { + b = do_ls(work); + dir += b; + } + break; + + case 4: + case 5: + /* retry getting data from /dev/random */ + b = get_dev_random(&work->output[work->filled], + work->needed - work->filled); + if (b > 0) + work->filled += b; + break; + + case 6: + if (sizeof(files) > 2 * sizeof(*files)) { + b = digest_file(work); + dig += b; + } + break; + + case 2: + default: /* to make sure we make some progress */ + work->output[work->filled++] = 0xff & + dst_s_quick_random(bytes); + b = 1; + break; + } + if (b > 0) + bytes += b; + } + return (work->filled); +} + + +/* + * dst_s_random() This function will return the requested number of bytes + * of randomness to the caller it will use the best available sources of + * randomness. + * The current order is to use /dev/random, precalculated randomness, and + * finaly use some system calls and programs to generate semi random data that + * is then digested to generate randomness. + * This function is thread safe as each thread uses its own context, but + * concurrent treads will affect each other as they update shared state + * information. + * It is strongly recommended that this function be called requesting a size + * that is not a multiple of the output of the hash function used. + * + * If /dev/random is not available this function is not suitable to generate + * large ammounts of data, rather it is suitable to seed a pseudo-random + * generator + * Returns the number of bytes put in the output buffer + */ +int +dst_s_random(u_char *output, int size) +{ + int n = 0, s, i; + static u_char old_unused[DST_HASH_SIZE * DST_NUM_HASHES]; + static int unused = 0; + + if (size <= 0 || output == NULL) + return (0); + + if (size >= 2048) + return (-1); + /* + * Read from /dev/random + */ + n = get_dev_random(output, size); + /* + * If old data is available and needed use it + */ + if (n < size && unused > 0) { + int need = size - n; + if (unused <= need) { + memcpy(output, old_unused, unused); + n += unused; + unused = 0; + } else { + memcpy(output, old_unused, need); + n += need; + unused -= need; + memcpy(old_unused, &old_unused[need], unused); + } + } + /* + * If we need more use the simulated randomness here. + */ + if (n < size) { + dst_work *my_work = (dst_work *) malloc(sizeof(dst_work)); + if (my_work == NULL) + return (n); + my_work->needed = size - n; + my_work->filled = 0; + my_work->output = (u_char *) malloc(my_work->needed + + DST_HASH_SIZE * + DST_NUM_HASHES); + my_work->file_digest = NULL; + if (my_work->output == NULL) + return (n); + memset(my_work->output, 0x0, my_work->needed); +/* allocate upto 4 different HMAC hash functions out of order */ +#if DST_NUM_HASHES >= 3 + my_work->hash[2] = get_hmac_key(3, DST_RANDOM_BLOCK_SIZE / 2); +#endif +#if DST_NUM_HASHES >= 2 + my_work->hash[1] = get_hmac_key(7, DST_RANDOM_BLOCK_SIZE / 6); +#endif +#if DST_NUM_HASHES >= 4 + my_work->hash[3] = get_hmac_key(5, DST_RANDOM_BLOCK_SIZE / 4); +#endif + my_work->hash[0] = get_hmac_key(1, DST_RANDOM_BLOCK_SIZE); + if (my_work->hash[0] == NULL) /* if failure bail out */ + return (n); + s = own_random(my_work); +/* if more generated than needed store it for future use */ + if (s >= my_work->needed) { + EREPORT(("dst_s_random(): More than needed %d >= %d\n", + s, my_work->needed)); + memcpy(&output[n], my_work->output, my_work->needed); + n += my_work->needed; + /* saving unused data for next time */ + unused = s - my_work->needed; + memcpy(old_unused, &my_work->output[my_work->needed], + unused); + } else { + /* XXXX This should not happen */ + EREPORT(("Not enough %d >= %d\n", s, my_work->needed)); + memcpy(&output[n], my_work->output, s); + n += my_work->needed; + } + +/* delete the allocated work area */ + for (i = 0; i < DST_NUM_HASHES; i++) { + dst_free_key(my_work->hash[i]->key); + SAFE_FREE(my_work->hash[i]); + } + SAFE_FREE(my_work->output); + SAFE_FREE(my_work); + } + return (n); +} + +/* + * A random number generator that is fast and strong + * this random number generator is based on HASHing data, + * the input to the digest function is a collection of <NUMBER_OF_COUNTERS> + * counters that is incremented between digest operations + * each increment operation amortizes to 2 bits changed in that value + * for 5 counters thus the input will amortize to have 10 bits changed + * The counters are initaly set using the strong random function above + * the HMAC key is selected by the same methold as the HMAC keys for the + * strong random function. + * Each set of counters is used for 2^25 operations + * + * returns the number of bytes written to the output buffer + * or negative number in case of error + */ +int +dst_s_semi_random(u_char *output, int size) +{ + static u_int32_t counter[DST_NUMBER_OF_COUNTERS]; + static u_char semi_old[DST_HASH_SIZE]; + static int semi_loc = 0, cnt = 0, hb_size = 0; + static DST_KEY *my_key = NULL; + prand_hash *hash; + int out = 0, i, n; + + if (output == NULL || size <= 0) + return (-2); + +/* check if we need a new key */ + if (my_key == NULL || cnt > (1 << 25)) { /* get HMAC KEY */ + if (my_key) + my_key->dk_func->destroy(my_key); + if ((hash = get_hmac_key(1, DST_RANDOM_BLOCK_SIZE)) == NULL) + return (0); + my_key = hash->key; +/* check if the key works stir the new key using some old random data */ + hb_size = dst_sign_data(SIG_MODE_ALL, my_key, NULL, + (u_char *) counter, sizeof(counter), + semi_old, sizeof(semi_old)); + if (hb_size <= 0) { + EREPORT(("dst_s_semi_random() Sign of alg %d failed %d\n", + my_key->dk_alg, hb_size)); + return (-1); + } +/* new set the counters to random values */ + dst_s_random((u_char *) counter, sizeof(counter)); + cnt = 0; + } +/* if old data around use it first */ + if (semi_loc < hb_size) { + if (size <= hb_size - semi_loc) { /* need less */ + memcpy(output, &semi_old[semi_loc], size); + semi_loc += size; + return (size); /* DONE */ + } else { + out = hb_size - semi_loc; + memcpy(output, &semi_old[semi_loc], out); + semi_loc += out; + } + } +/* generate more randome stuff */ + while (out < size) { + /* + * modify at least one bit by incrementing at least one counter + * based on the last bit of the last counter updated update + * the next one. + * minimaly this operation will modify at least 1 bit, + * amortized 2 bits + */ + for (n = 0; n < DST_NUMBER_OF_COUNTERS; n++) + i = (int) counter[n]++; + + i = dst_sign_data(SIG_MODE_ALL, my_key, NULL, + (u_char *) counter, hb_size, + semi_old, sizeof(semi_old)); + if (i != hb_size) + EREPORT(("HMAC SIGNATURE FAILURE %d\n", i)); + cnt++; + if (size - out < i) /* Not all data is needed */ + semi_loc = i = size - out; + memcpy(&output[out], semi_old, i); + out += i; + } + return (out); +} |