-/* Max size of additional input and personalization string. */
-# define DRBG_MAX_LENGTH 4096
+/*
+ * Maximum input size for the DRBG (entropy, nonce, personalization string)
+ *
+ * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
+ *
+ * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
+ */
+# define DRBG_MAX_LENGTH INT32_MAX
+
+
/*
- * The quotient between max_{entropy,nonce}len and min_{entropy,nonce}len
+ * Maximum allocation size for RANDOM_POOL buffers
*
- * 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.
+ * The max_len value for the buffer provided to the rand_drbg_get_entropy()
+ * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
+ * is used. Since this is much too large to be allocated, the rand_pool_new()
+ * function chooses more modest values as default pool length, bounded
+ * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
+ *
+ * The choice of the RAND_POOL_FACTOR is large enough such that the
+ * RAND_POOL can store a random input which has a lousy entropy rate of
+ * 8/256 (= 0.03125) bits per byte. This input will be sent through the
+ * derivation function which 'compresses' the low quality input into a
+ * high quality output.
+ *
+ * The factor 1.5 below is the pessimistic estimate for the extra amount
+ * of entropy required when no get_nonce() callback is defined.
+ */
+# define RAND_POOL_FACTOR 256
+# define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
+ 3 * (RAND_DRBG_STRENGTH / 16))
+/*
+ * = (RAND_POOL_FACTOR * \
+ * 1.5 * (RAND_DRBG_STRENGTH / 8))
*/
-# define DRBG_MINMAX_FACTOR 128
/* DRBG status values */
* The state of a DRBG AES-CTR.
*/
typedef struct rand_drbg_ctr_st {
- AES_KEY ks;
+ EVP_CIPHER_CTX *ctx;
+ EVP_CIPHER_CTX *ctx_df;
+ const EVP_CIPHER *cipher;
size_t keylen;
unsigned char K[32];
unsigned char V[16];
- /* Temp variables used by derivation function */
- AES_KEY df_ks;
- AES_KEY df_kxks;
/* Temporary block storage used by ctr_df */
unsigned char bltmp[16];
size_t bltmp_pos;
} RAND_DRBG_CTR;
+/*
+ * The 'random pool' acts as a dumb container for collecting random
+ * input from various entropy sources. The pool has no knowledge about
+ * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
+ * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
+ * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
+ * 4) cleanup the random pool again.
+ *
+ * The random pool contains no locking mechanism because its scope and
+ * lifetime is intended to be restricted to a single stack frame.
+ */
+struct rand_pool_st {
+ unsigned char *buffer; /* points to the beginning of the random pool */
+ size_t len; /* current number of random bytes contained in the pool */
+
+ int attached; /* true pool was attached to existing buffer */
+
+ size_t min_len; /* minimum number of random bytes requested */
+ size_t max_len; /* maximum number of random bytes (allocated buffer size) */
+ size_t entropy; /* current entropy count in bits */
+ size_t entropy_requested; /* requested entropy count in bits */
+};
+
/*
* The state of all types of DRBGs, even though we only have CTR mode
* right now.
CRYPTO_RWLOCK *lock;
RAND_DRBG *parent;
int secure; /* 1: allocated on the secure heap, 0: otherwise */
- int nid; /* the underlying algorithm */
+ int type; /* the nid of the underlying algorithm */
+ /*
+ * Stores the value of the rand_fork_count global as of when we last
+ * reseeded. The DRG reseeds automatically whenever drbg->fork_count !=
+ * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
+ * the child process.
+ */
int fork_count;
unsigned short flags; /* various external flags */
/*
- * The random pool is used by RAND_add()/drbg_add() to attach random
+ * The random_data 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
/* The global RAND method, and the global buffer and DRBG instance. */
extern RAND_METHOD rand_meth;
-/* How often we've forked (only incremented in child). */
+/*
+ * A "generation count" of forks. Incremented in the child process after a
+ * fork. Since rand_fork_count is increment-only, and only ever written to in
+ * the child process of the fork, which is guaranteed to be single-threaded, no
+ * locking is needed for normal (read) accesses; the rest of pthread fork
+ * processing is assumed to introduce the necessary memory barriers. Sibling
+ * children of a given parent will produce duplicate values, but this is not
+ * problematic because the reseeding process pulls input from the system CSPRNG
+ * and/or other global sources, so the siblings will end up generating
+ * different output streams.
+ */
extern int rand_fork_count;
/* DRBG helpers */
projects / oweals / openssl.git / blobdiff