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ch2_truerandom          1 #include <stdio.h>
ch2_truerandom          2 #include <stdlib.h>
ch2_truerandom          3 #include <string.h>
ch2_truerandom          4 
ch2_truerandom          5 #include <fcntl.h>
ch2_truerandom          6 #include <unistd.h>
ch2_truerandom          7 #include <termios.h>
ch2_truerandom          8 #include <errno.h>
ch2_truerandom          9 
ch2_truerandom         10 #include "smg_rsa.h"
ch2_truerandom         11 
ch2_truerandom         12 
ch2_truerandom         13 int set_usb_attribs(int fd, int speed) {
ch2_truerandom         14 	struct termios tty;
ch2_truerandom         15 	if (tcgetattr(fd, &tty) < 0) {
ch2_truerandom         16 		return -1;
ch2_truerandom         17 	}
ch2_truerandom         18 
eucrypt_ch4_rpng       19 	/* input and output speeds */
ch2_truerandom         20 	cfsetospeed(&tty, (speed_t)speed);
ch2_truerandom         21 	cfsetispeed(&tty, (speed_t)speed);
ch2_truerandom         22 
eucrypt_ch4_rpng       23 	/* raw */
eucrypt_ch4_rpng       24 	tty.c_lflag &= ~(ECHO | ECHOE | ECHOK);
eucrypt_ch4_rpng       25 	tty.c_oflag &= ~OPOST;
ch2_truerandom         26 
eucrypt_ch4_rpng       27 	/* read at least one octet at a time; BLOCK until at least VMIN octets read */
ch2_truerandom         28 	tty.c_cc[VMIN] = 1;
eucrypt_ch4_rpng       29 	tty.c_cc[VTIME] = 0;
ch2_truerandom         30 
eucrypt_ch4_rpng       31 	if (tcsetattr(fd, TCSAFLUSH, &tty) != 0)
ch2_truerandom         32 		return -1;
ch2_truerandom         33 
ch2_truerandom         34 	return 0;
ch2_truerandom         35 }
ch2_truerandom         36 
ch2_truerandom         37 int open_entropy_source(char* source_name) {
ch2_truerandom         38 	int in, err;
ch2_truerandom         39 
ch2_truerandom         40 	in = open(source_name, O_RDONLY | O_NOCTTY | O_NDELAY);
ch2_truerandom         41 	if (in == -1) {
ch2_truerandom         42 		printf("ERROR: failure to open entropy source %s: %s\n", source_name, strerror(errno));
ch2_truerandom         43 		return in;	//failed to access entropy source
ch2_truerandom         44 	}
ch2_truerandom         45 
ch2_truerandom         46 	fcntl(in, F_SETFL, 0);
ch2_truerandom         47 
ch2_truerandom         48 	err = set_usb_attribs(in, B115200);
ch2_truerandom         49 	if (err==-1) {
ch2_truerandom         50 		printf("Error setting attributes on %s: %s\n", source_name, strerror(errno));
ch2_truerandom         51 		return err;
ch2_truerandom         52 	}
ch2_truerandom         53 
ch2_truerandom         54 	return in;	//source opened, return its descriptor
ch2_truerandom         55 }
ch2_truerandom         56 
ch2_truerandom         57 int get_random_octets_from(int noctets, unsigned char *out, int from) {
ch2_truerandom         58 
ch2_truerandom         59 	int nread;
ch2_truerandom         60 	int total = 0;
ch2_truerandom         61 
ch2_truerandom         62 	while (total < noctets) {
eucrypt_ch3_mille...   63 		errno = 0;
ch2_truerandom         64 		nread = read(from, out+total, noctets-total);
ch2_truerandom         65 		//on interrupt received just try again
ch2_truerandom         66 		if (nread == -1 && errno == EINTR)
ch2_truerandom         67 			continue;
ch2_truerandom         68 		//on error condition abort
eucrypt_ch3_mille...   69 		if (errno != 0 && (nread == -1 || nread == 0)) {
eucrypt_ch3_mille...   70 			printf("Error reading from entropy source %s after %d read: %s\n", ENTROPY_SOURCE, total, strerror(errno));
ch2_truerandom         71 			return total;		//total read so far
ch2_truerandom         72 		}
ch2_truerandom         73 
ch2_truerandom         74 		if (nread > 0)
ch2_truerandom         75 			total = total + nread;
ch2_truerandom         76 	}
ch2_truerandom         77 	return total;	//return number of octets read
ch2_truerandom         78 }
ch2_truerandom         79 
ch2_truerandom         80 int get_random_octets(int noctets, unsigned char *out) {
ch2_truerandom         81 	int in;
ch2_truerandom         82 	int nread = 0;
ch2_truerandom         83 
ch2_truerandom         84 	in = open_entropy_source(ENTROPY_SOURCE);
ch2_truerandom         85 	if (in > 0) {
ch2_truerandom         86 		nread = get_random_octets_from(noctets, out, in);
ch2_truerandom         87 		close(in);
ch2_truerandom         88 	}
ch2_truerandom         89 	return nread;
ch2_truerandom         90 }
ch2_truerandom         91 
eucrypt_ch13_smg_rng   92 int rng_dirty_float(float *n) {
eucrypt_ch13_smg_rng   93   int status;   /* for aborting in case of error */
eucrypt_ch13_smg_rng   94   uint32_t r;   /* a random value on 32 bits */
eucrypt_ch13_smg_rng   95   uint32_t maxval = 0xffffffff; /* maximum value on 32 bits */
eucrypt_ch13_smg_rng   96 
eucrypt_ch13_smg_rng   97   /* obtain a random number on 32 bits using ENTROPY_SOURCE */
eucrypt_ch13_smg_rng   98   status = rng_uint32( &r );
eucrypt_ch13_smg_rng   99   if ( status < 0 )
eucrypt_ch13_smg_rng  100     return status;
eucrypt_ch13_smg_rng  101 
eucrypt_ch13_smg_rng  102   /* calculate and assign the floating-point random value as (r*1.0)/max val */
eucrypt_ch13_smg_rng  103   /* multiplication by 1.0 IS NEEDED to do float division rather than int div*/
eucrypt_ch13_smg_rng  104   *n = ( r * 1.0 ) / maxval;
eucrypt_ch13_smg_rng  105 
eucrypt_ch13_smg_rng  106   return 1;
eucrypt_ch13_smg_rng  107 }
eucrypt_ch13_smg_rng  108 
eucrypt_ch13_smg_rng  109 int rng_float_754_1985(float *n) {
eucrypt_ch13_smg_rng  110   /* Single float ieee 754/1985 has 23 bits that can be set for the mantissa
eucrypt_ch13_smg_rng  111    * (and one implicit bit=1).
eucrypt_ch13_smg_rng  112    * Full single float ieee 754/1985 representation takes 4 octets in total.
eucrypt_ch13_smg_rng  113    */
eucrypt_ch13_smg_rng  114   int noctets = 4; /* number of octets to read from ENTROPY_SOURCE */
eucrypt_ch13_smg_rng  115   int nread;       /* number of octets *read* from ENTROPY_SOURCE  */
eucrypt_ch13_smg_rng  116   unsigned char bits[ noctets ]; /* the random bits from ENTROPY_SOURCE */ 
eucrypt_ch13_smg_rng  117   int oSignExp, oExpM;/* offsets for sign+exponent octet, exponent+mantissa*/
eucrypt_ch13_smg_rng  118 
eucrypt_ch13_smg_rng  119   /* obtain random bits */
eucrypt_ch13_smg_rng  120   nread = get_random_octets( noctets, bits );
eucrypt_ch13_smg_rng  121 
eucrypt_ch13_smg_rng  122   if (nread != noctets )
eucrypt_ch13_smg_rng  123     return -1;  /* something wrong at reading from ENTROPY_SOURCE, abort */
eucrypt_ch13_smg_rng  124 
eucrypt_ch13_smg_rng  125   /* set offsets for bit diddling depending on endianness of iron */
eucrypt_ch13_smg_rng  126   if (is_bigendian()) {
eucrypt_ch13_smg_rng  127     oSignExp = 0;
eucrypt_ch13_smg_rng  128     oExpM = 1;
eucrypt_ch13_smg_rng  129   }
eucrypt_ch13_smg_rng  130   else {
eucrypt_ch13_smg_rng  131     oSignExp = 3;
eucrypt_ch13_smg_rng  132     oExpM = 2;
eucrypt_ch13_smg_rng  133   }
eucrypt_ch13_smg_rng  134 
eucrypt_ch13_smg_rng  135   /* set sign=0; exponent=127; explicit mantissa = random bits (23 bits) */
eucrypt_ch13_smg_rng  136   *(bits+oExpM) = *(bits+2) | 0x80;  /* one bit of exponent set */
eucrypt_ch13_smg_rng  137   *(bits+oSignExp) = 0x3f;           /* sign=0; exponent bits for 127 */
eucrypt_ch13_smg_rng  138 
eucrypt_ch13_smg_rng  139   /* now copy the bits to the result var (i.e. as a float's representation */
eucrypt_ch13_smg_rng  140   memcpy( n, bits, noctets );
eucrypt_ch13_smg_rng  141   return 1;
eucrypt_ch13_smg_rng  142 }
eucrypt_ch13_smg_rng  143 
eucrypt_ch13_smg_rng  144 int rng_uint32( uint32_t *n ) {
eucrypt_ch13_smg_rng  145   int noctets = 4;  /*  32 bits aka 4 octets to read from ENTROPY_SOURCE     */
eucrypt_ch13_smg_rng  146   int nread;        /*  the number of octets read from ENTROPY_SOURCE        */
eucrypt_ch13_smg_rng  147   unsigned char bits[ noctets ]; /* for storing the bits from ENTROPY_SOURCE */
eucrypt_ch13_smg_rng  148 
eucrypt_ch13_smg_rng  149   /* read random 32 bits from ENTROPY_SOURCE */
eucrypt_ch13_smg_rng  150   nread = get_random_octets( noctets, bits );
eucrypt_ch13_smg_rng  151   if ( nread != noctets )
eucrypt_ch13_smg_rng  152     return -1;
eucrypt_ch13_smg_rng  153 
eucrypt_ch13_smg_rng  154   /* copy the random bits to n, to be interpreted as uint32 */
eucrypt_ch13_smg_rng  155   /* endianness is irrelevant here - the bits are random anyway */
eucrypt_ch13_smg_rng  156   memcpy( n, bits, noctets );
eucrypt_ch13_smg_rng  157 
eucrypt_ch13_smg_rng  158   return 1;
eucrypt_ch13_smg_rng  159 }
eucrypt_ch13_smg_rng  160 
eucrypt_ch13_smg_rng  161 int rng_uint64( uint64_t *n ) {
eucrypt_ch13_smg_rng  162   int noctets = 8;  /*  64 bits aka 8 octets to read from ENTROPY_SOURCE     */
eucrypt_ch13_smg_rng  163   int nread;        /*  the number of octets read from ENTROPY_SOURCE        */
eucrypt_ch13_smg_rng  164   unsigned char bits[ noctets ]; /* for storing the bits from ENTROPY_SOURCE */
eucrypt_ch13_smg_rng  165 
eucrypt_ch13_smg_rng  166   /* read random 64 bits from ENTROPY_SOURCE */
eucrypt_ch13_smg_rng  167   nread = get_random_octets( noctets, bits );
eucrypt_ch13_smg_rng  168   if ( nread != noctets )
eucrypt_ch13_smg_rng  169     return -1;
eucrypt_ch13_smg_rng  170 
eucrypt_ch13_smg_rng  171   /* copy the random bits to n, to be interpreted as uint64 */
eucrypt_ch13_smg_rng  172   /* endianness is irrelevant here - the bits are random anyway */
eucrypt_ch13_smg_rng  173   memcpy( n, bits, noctets );
eucrypt_ch13_smg_rng  174 
eucrypt_ch13_smg_rng  175   return 1;
eucrypt_ch13_smg_rng  176 }