raw
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