diff options
| -rw-r--r-- | crypto.c | 39 | ||||
| -rw-r--r-- | crypto.h | 3 |
2 files changed, 31 insertions, 11 deletions
@@ -1260,6 +1260,24 @@ static uint8_t *nonce_data = NULL; /* GLOBAL */ static const md_kt_t *nonce_md = NULL; /* GLOBAL */ static int nonce_secret_len = 0; /* GLOBAL */ +/* Reset the nonce value, also done periodically to refresh entropy */ +static void +prng_reset_nonce () +{ + const int size = md_kt_size (nonce_md) + nonce_secret_len; +#if 1 /* Must be 1 for real usage */ + if (!rand_bytes (nonce_data, size)) + msg (M_FATAL, "ERROR: Random number generator cannot obtain entropy for PRNG"); +#else + /* Only for testing -- will cause a predictable PRNG sequence */ + { + int i; + for (i = 0; i < size; ++i) + nonce_data[i] = (uint8_t) i; + } +#endif +} + void prng_init (const char *md_name, const int nonce_secret_len_parm) { @@ -1274,17 +1292,7 @@ prng_init (const char *md_name, const int nonce_secret_len_parm) dmsg (D_CRYPTO_DEBUG, "PRNG init md=%s size=%d", md_kt_name(nonce_md), size); nonce_data = (uint8_t*) malloc (size); check_malloc_return (nonce_data); -#if 1 /* Must be 1 for real usage */ - if (!rand_bytes (nonce_data, size)) - msg (M_FATAL, "ERROR: Random number generator cannot obtain entropy for PRNG"); -#else - /* Only for testing -- will cause a predictable PRNG sequence */ - { - int i; - for (i = 0; i < size; ++i) - nonce_data[i] = (uint8_t) i; - } -#endif + prng_reset_nonce(); } } } @@ -1301,6 +1309,8 @@ prng_uninit (void) void prng_bytes (uint8_t *output, int len) { + static int32_t processed = 0; + if (nonce_md) { md_ctx_t ctx; @@ -1313,6 +1323,13 @@ prng_bytes (uint8_t *output, int len) memcpy (output, nonce_data, blen); output += blen; len -= blen; + + /* Ensure that random data is reset regularly */ + processed += blen; + if(processed > PRNG_NONCE_RESET_BYTES) { + prng_reset_nonce(); + processed = 0; + } } } else @@ -295,6 +295,9 @@ void crypto_adjust_frame_parameters(struct frame *frame, /* Maximum length of the nonce used by the PRNG */ #define NONCE_SECRET_LEN_MAX 64 +/** Number of bytes of random to allow before resetting the nonce */ +#define PRNG_NONCE_RESET_BYTES 1024 + /** * Pseudo-random number generator initialisation. * (see \c prng_rand_bytes()) |