| 1 | /* |
| 2 | * Noise generation for PuTTY's cryptographic random number |
| 3 | * generator. |
| 4 | */ |
| 5 | |
| 6 | #include <stdio.h> |
| 7 | #include <fcntl.h> |
| 8 | #include <unistd.h> |
| 9 | #include <sys/time.h> |
| 10 | |
| 11 | #include "putty.h" |
| 12 | #include "ssh.h" |
| 13 | #include "storage.h" |
| 14 | |
| 15 | /* |
| 16 | * FIXME. This module currently depends critically on /dev/urandom, |
| 17 | * because it has no fallback mechanism for doing anything else. |
| 18 | */ |
| 19 | |
| 20 | static void read_dev_urandom(char *buf, int len) |
| 21 | { |
| 22 | int fd; |
| 23 | int ngot, ret; |
| 24 | |
| 25 | fd = open("/dev/urandom", O_RDONLY); |
| 26 | if (fd < 0) { |
| 27 | perror("/dev/urandom: open"); |
| 28 | exit(1); |
| 29 | } |
| 30 | |
| 31 | ngot = 0; |
| 32 | while (ngot < len) { |
| 33 | ret = read(fd, buf+ngot, len-ngot); |
| 34 | if (ret < 0) { |
| 35 | perror("/dev/urandom: read"); |
| 36 | exit(1); |
| 37 | } |
| 38 | ngot += ret; |
| 39 | } |
| 40 | } |
| 41 | |
| 42 | /* |
| 43 | * This function is called once, at PuTTY startup. Currently it |
| 44 | * will read 32 bytes out of /dev/urandom and seed the internal |
| 45 | * generator with them. |
| 46 | */ |
| 47 | |
| 48 | void noise_get_heavy(void (*func) (void *, int)) |
| 49 | { |
| 50 | char buf[32]; |
| 51 | read_dev_urandom(buf, sizeof(buf)); |
| 52 | func(buf, sizeof(buf)); |
| 53 | } |
| 54 | |
| 55 | void random_save_seed(void) |
| 56 | { |
| 57 | /* Currently we do nothing here. FIXME? */ |
| 58 | } |
| 59 | |
| 60 | /* |
| 61 | * This function is called every time the urandom pool needs |
| 62 | * stirring, and will acquire the system time. |
| 63 | */ |
| 64 | void noise_get_light(void (*func) (void *, int)) |
| 65 | { |
| 66 | struct timeval tv; |
| 67 | gettimeofday(&tv, NULL); |
| 68 | func(&tv, sizeof(tv)); |
| 69 | } |
| 70 | |
| 71 | /* |
| 72 | * This function is called on a timer, and it will just pull some |
| 73 | * stuff out of /dev/urandom. FIXME: really I suspect we ought not |
| 74 | * to deplete /dev/urandom like this. Better to grab something more |
| 75 | * harmless. |
| 76 | */ |
| 77 | void noise_regular(void) |
| 78 | { |
| 79 | char buf[4]; |
| 80 | read_dev_urandom(buf, sizeof(buf)); |
| 81 | random_add_noise(buf, sizeof(buf)); |
| 82 | } |
| 83 | |
| 84 | /* |
| 85 | * This function is called on every keypress or mouse move, and |
| 86 | * will add the current time to the noise pool. It gets the scan |
| 87 | * code or mouse position passed in, and adds that too. |
| 88 | */ |
| 89 | void noise_ultralight(unsigned long data) |
| 90 | { |
| 91 | struct timeval tv; |
| 92 | gettimeofday(&tv, NULL); |
| 93 | random_add_noise(&tv, sizeof(tv)); |
| 94 | random_add_noise(&data, sizeof(data)); |
| 95 | } |