# include <openssl/ec.h>
# include "internal/rand.h"
-/*
- * Amount of randomness (in bytes) we want for initial seeding.
- * This is based on the fact that we use AES-128 as the CRBG, and
- * that we use the derivation function. If either of those changes,
- * (see rand_init() in rand_lib.c), change this.
- */
-# define RANDOMNESS_NEEDED 16
+/* How many times to read the TSC as a randomness source. */
+# define TSC_READ_COUNT 4
+
+/* Maximum reseed intervals */
+# define MAX_RESEED_INTERVAL (1 << 24)
+# define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
+
+/* Default reseed intervals */
+# define MASTER_RESEED_INTERVAL (1 << 8)
+# define SLAVE_RESEED_INTERVAL (1 << 16)
+# define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
+# define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
-/* Maximum amount of randomness to hold in RAND_BYTES_BUFFER. */
-# define MAX_RANDOMNESS_HELD (4 * RANDOMNESS_NEEDED)
-/* Maximum count allowed in reseeding */
-# define MAX_RESEED (1 << 24)
-/* How often we call RAND_poll() in drbg_entropy_from_system */
-# define RAND_POLL_RETRIES 8
+/* Max size of additional input and personalization string. */
+# define DRBG_MAX_LENGTH 4096
-/* Max size of entropy, addin, etc. Larger than any reasonable value */
-# define DRBG_MAX_LENGTH 0x7ffffff0
+/*
+ * The quotient between max_{entropy,nonce}len and min_{entropy,nonce}len
+ *
+ * The current factor is large enough that the RAND_POOL can store a
+ * random input which has a lousy entropy rate of 0.0625 bits per byte.
+ * This input will be sent through the derivation function which 'compresses'
+ * the low quality input into a high quality output.
+ */
+# define DRBG_MINMAX_FACTOR 128
/* DRBG status values */
typedef enum drbg_status_e {
DRBG_UNINITIALISED,
DRBG_READY,
- DRBG_RESEED,
DRBG_ERROR
} DRBG_STATUS;
-/*
- * A buffer of random bytes to be fed as "entropy" into the DRBG. RAND_add()
- * adds data to the buffer, and the drbg_entropy_from_system() pulls data from
- * the buffer. We have a separate data structure because of the way the
- * API is defined; otherwise we'd run into deadlocks (RAND_bytes ->
- * RAND_DRBG_generate* -> drbg_entropy_from_system -> RAND_poll -> RAND_add ->
- * drbg_add*; the functions with an asterisk lock).
- */
-typedef struct rand_bytes_buffer_st {
- CRYPTO_RWLOCK *lock;
- size_t size;
- size_t curr;
- unsigned char *buff;
-} RAND_BYTES_BUFFER;
-
/*
* The state of a DRBG AES-CTR.
*/
CRYPTO_RWLOCK *lock;
RAND_DRBG *parent;
int nid; /* the underlying algorithm */
+ int fork_count;
unsigned short flags; /* various external flags */
- unsigned short filled;
+
/*
- * This is a fixed-size buffer, but we malloc to make it a little
- * harder to find; a classic security/performance trade-off.
+ * The random pool is used by RAND_add()/drbg_add() to attach random
+ * data to the global drbg, such that the rand_drbg_get_entropy() callback
+ * can pull it during instantiation and reseeding. This is necessary to
+ * reconcile the different philosophies of the RAND and the RAND_DRBG
+ * with respect to how randomness is added to the RNG during reseeding
+ * (see PR #4328).
+ */
+ RAND_POOL *pool;
+
+ /*
+ * The following parameters are setup by the per-type "init" function.
+ *
+ * Currently the only type is CTR_DRBG, its init function is ctr_init().
+ *
+ * The parameters are closely related to the ones described in
+ * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
+ * crucial difference: In the NIST standard, all counts are given
+ * in bits, whereas in OpenSSL entropy counts are given in bits
+ * and buffer lengths are given in bytes.
+ *
+ * Since this difference has lead to some confusion in the past,
+ * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
+ * the 'len' suffix has been added to all buffer sizes for
+ * clarification.
*/
- int size;
- unsigned char *randomness;
- /* These parameters are setup by the per-type "init" function. */
int strength;
size_t max_request;
- size_t min_entropy, max_entropy;
- size_t min_nonce, max_nonce;
- size_t max_pers, max_adin;
- unsigned int reseed_counter;
+ size_t min_entropylen, max_entropylen;
+ size_t min_noncelen, max_noncelen;
+ size_t max_perslen, max_adinlen;
+
+ /* Counts the number of generate requests since the last reseed. */
+ unsigned int generate_counter;
+ /*
+ * Maximum number of generate requests until a reseed is required.
+ * This value is ignored if it is zero.
+ */
unsigned int reseed_interval;
+ /* Stores the time when the last reseeding occurred */
+ time_t reseed_time;
+ /*
+ * Specifies the maximum time interval (in seconds) between reseeds.
+ * This value is ignored if it is zero.
+ */
+ time_t reseed_time_interval;
+ /*
+ * Counts the number of reseeds since instantiation.
+ * This value is ignored if it is zero.
+ *
+ * This counter is used only for seed propagation from the <master> DRBG
+ * to its two children, the <public> and <private> DRBG. This feature is
+ * very special and its sole purpose is to ensure that any randomness which
+ * is added by RAND_add() or RAND_seed() will have an immediate effect on
+ * the output of RAND_bytes() resp. RAND_priv_bytes().
+ */
+ unsigned int reseed_counter;
+
size_t seedlen;
DRBG_STATUS state;
/* The global RAND method, and the global buffer and DRBG instance. */
extern RAND_METHOD rand_meth;
-extern RAND_BYTES_BUFFER rand_bytes;
-extern RAND_DRBG rand_drbg;
+
+/* How often we've forked (only incremented in child). */
+extern int rand_fork_count;
/* Hardware-based seeding functions. */
-void rand_read_tsc(RAND_poll_fn cb, void *arg);
-int rand_read_cpu(RAND_poll_fn cb, void *arg);
+size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool);
+size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool);
/* DRBG entropy callbacks. */
-void drbg_release_entropy(RAND_DRBG *drbg, unsigned char *out);
-size_t drbg_entropy_from_parent(RAND_DRBG *drbg,
- unsigned char **pout,
- int entropy, size_t min_len, size_t max_len);
-size_t drbg_entropy_from_system(RAND_DRBG *drbg,
- unsigned char **pout,
- int entropy, size_t min_len, size_t max_len);
+size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
+ unsigned char **pout,
+ int entropy, size_t min_len, size_t max_len);
+void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
+ unsigned char *out, size_t outlen);
+
+/* DRBG helpers */
+int rand_drbg_restart(RAND_DRBG *drbg,
+ const unsigned char *buffer, size_t len, size_t entropy);
/* DRBG functions implementing AES-CTR */
int ctr_init(RAND_DRBG *drbg);
int ctr_uninstantiate(RAND_DRBG *drbg);
int ctr_instantiate(RAND_DRBG *drbg,
- const unsigned char *ent, size_t entlen,
+ const unsigned char *entropy, size_t entropylen,
const unsigned char *nonce, size_t noncelen,
const unsigned char *pers, size_t perslen);
int ctr_reseed(RAND_DRBG *drbg,
- const unsigned char *ent, size_t entlen,
+ const unsigned char *entropy, size_t entropylen,
const unsigned char *adin, size_t adinlen);
int ctr_generate(RAND_DRBG *drbg,
unsigned char *out, size_t outlen,
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