@@ -46,7 +46,7 @@
#define TEST 0
#endif
-static int read_random(uint32_t *dst, const char *file)
+static int read_random(uint8_t *dst, size_t len, const char *file)
{
#if HAVE_UNISTD_H
FILE *fp = avpriv_fopen_utf8(file, "r");
@@ -54,10 +54,10 @@ static int read_random(uint32_t *dst, const char *file)
if (!fp)
return AVERROR_UNKNOWN;
- err = fread(dst, 1, sizeof(*dst), fp);
+ err = fread(dst, 1, len, fp);
fclose(fp);
- if (err != sizeof(*dst))
+ if (err != len)
return AVERROR_UNKNOWN;
return 0;
@@ -121,27 +121,38 @@ static uint32_t get_generic_seed(void)
return AV_RB32(digest) + AV_RB32(digest + 16);
}
-uint32_t av_get_random_seed(void)
+int av_random_bytes(uint8_t* buf, size_t len)
{
- uint32_t seed;
+ int err;
#if HAVE_BCRYPT
BCRYPT_ALG_HANDLE algo_handle;
NTSTATUS ret = BCryptOpenAlgorithmProvider(&algo_handle, BCRYPT_RNG_ALGORITHM,
MS_PRIMITIVE_PROVIDER, 0);
if (BCRYPT_SUCCESS(ret)) {
- NTSTATUS ret = BCryptGenRandom(algo_handle, (UCHAR*)&seed, sizeof(seed), 0);
+ NTSTATUS ret = BCryptGenRandom(algo_handle, (PUCHAR)buf, len, 0);
BCryptCloseAlgorithmProvider(algo_handle, 0);
if (BCRYPT_SUCCESS(ret))
- return seed;
+ return 0;
}
#endif
#if HAVE_ARC4RANDOM
- return arc4random();
+ arc4random_buf(buf, len);
+ return 0;
#endif
- if (!read_random(&seed, "/dev/urandom"))
- return seed;
- return get_generic_seed();
+ err = read_random(buf, len, "/dev/urandom");
+
+ return err;
+}
+
+uint32_t av_get_random_seed(void)
+{
+ uint32_t seed;
+
+ if (av_random_bytes((uint8_t *)&seed, sizeof(seed)) < 0)
+ return get_generic_seed();
+
+ return seed;
}
@@ -36,6 +36,19 @@
*/
uint32_t av_get_random_seed(void);
+/**
+ * Generate cryptographically secure random data, i.e. suitable for use as
+ * encryption keys and similar.
+ *
+ * @param buf buffer into which the random data will be written
+ * @param len size of buf in bytes
+ *
+ * @retval 0 success, len bytes of random data was written
+ * into buf
+ * @retval "a negative AVERROR code" random data could not be generated
+ */
+int av_random_bytes(uint8_t *buf, size_t len);
+
/**
* @}
*/
Uses the existing code for av_get_random_seed() to return a buffer with cryptographically secure random data, or an error if none could be generated. Signed-off-by: James Almer <jamrial@gmail.com> --- libavutil/random_seed.c | 33 ++++++++++++++++++++++----------- libavutil/random_seed.h | 13 +++++++++++++ 2 files changed, 35 insertions(+), 11 deletions(-)