pidgin/pidgin

simple: Re-write gensesskey using nettle.

2020-05-18, Elliott Sales de Andrade
188bfd55da54
Parents 0908be6e73de
Children 3f7b41f7fae8
simple: Re-write gensesskey using nettle.

This is within a `HAVE_NETTLE` block, so there's no need to surmise
about cryptographically-secure RNGs, because we have one available to
use directly.
1 files changed, 14 insertions(+), 23 deletions(-)
  • +14 -23
    libpurple/protocols/simple/ntlm.c
    • --- a/libpurple/protocols/simple/ntlm.c Wed May 13 02:01:23 2020 +0000
    +++ b/libpurple/protocols/simple/ntlm.c Mon May 18 20:13:50 2020 -0400
    @@ -29,6 +29,7 @@
    #ifdef HAVE_NETTLE
    #include <nettle/des.h>
    #include <nettle/md4.h>
    +#include <nettle/yarrow.h>
    #endif
    #include <string.h>
    @@ -155,42 +156,32 @@
    des_ecb_encrypt(plaintext, results + 16, key);
    }
    -/*
    - * TODO: We think we should be using cryptographically secure random numbers
    - * here. We think the rand() function is probably bad. We think
    - * /dev/urandom is a step up, but using a random function from an SSL
    - * library would probably be best. In Windows we could possibly also
    - * use CryptGenRandom.
    - */
    static void
    gensesskey(char *buffer)
    {
    int fd;
    int i;
    - ssize_t red = 0;
    + ssize_t bytes_seeded = 0;
    + uint8_t seed[YARROW256_SEED_FILE_SIZE];
    + struct yarrow256_ctx ctx;
    fd = open("/dev/urandom", O_RDONLY);
    if (fd >= 0) {
    - red = read(fd, buffer, 16);
    - if (red < 0) {
    - purple_debug_warning("ntlm", "Error reading from /dev/urandom: %s."
    - " Falling back to inferior method.\n", g_strerror(errno));
    - red = 0;
    - } else if (red < 16) {
    - purple_debug_warning("ntlm", "Tried reading 16 bytes from "
    - "/dev/urandom but only got %"
    - G_GSSIZE_FORMAT ". Falling back to "
    - "inferior method\n", (gssize)red);
    + bytes_seeded = read(fd, seed, YARROW256_SEED_FILE_SIZE);
    + if (bytes_seeded < 0) {
    + bytes_seeded = 0;
    }
    close(fd);
    - } else {
    - purple_debug_warning("ntlm", "Error opening /dev/urandom: %s."
    - " Falling back to inferior method.\n", g_strerror(errno));
    }
    - for (i = red; i < 16; i++) {
    - buffer[i] = (char)(g_random_int() & 0xff);
    + for (i = bytes_seeded; i < YARROW256_SEED_FILE_SIZE; i++) {
    + seed[i] = (char)(g_random_int() & 0xff);
    }
    +
    + yarrow256_init(&ctx, 0, NULL);
    + yarrow256_seed(&ctx, YARROW256_SEED_FILE_SIZE, seed);
    + yarrow256_random(&ctx, YARROW256_SEED_FILE_SIZE, seed);
    + yarrow256_random(&ctx, 16, (uint8_t *)buffer);
    }
    #endif /* HAVE_NETTLE */