/* * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #ifndef HEADER_RAND_LCL_H # define HEADER_RAND_LCL_H # include # include # include # include # include # include # include "internal/numbers.h" /* 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 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 /* * Maximum allocation size for RANDOM_POOL buffers * * 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)) */ /* DRBG status values */ typedef enum drbg_status_e { DRBG_UNINITIALISED, DRBG_READY, DRBG_ERROR } DRBG_STATUS; /* intantiate */ typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx, const unsigned char *ent, size_t entlen, const unsigned char *nonce, size_t noncelen, const unsigned char *pers, size_t perslen); /* reseed */ typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx, const unsigned char *ent, size_t entlen, const unsigned char *adin, size_t adinlen); /* generat output */ typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx, unsigned char *out, size_t outlen, const unsigned char *adin, size_t adinlen); /* uninstantiate */ typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx); /* * The DRBG methods */ typedef struct rand_drbg_method_st { RAND_DRBG_instantiate_fn instantiate; RAND_DRBG_reseed_fn reseed; RAND_DRBG_generate_fn generate; RAND_DRBG_uninstantiate_fn uninstantiate; } RAND_DRBG_METHOD; /* * The state of a DRBG AES-CTR. */ typedef struct rand_drbg_ctr_st { EVP_CIPHER_CTX *ctx; EVP_CIPHER_CTX *ctx_df; const EVP_CIPHER *cipher; size_t keylen; unsigned char K[32]; unsigned char V[16]; /* Temporary block storage used by ctr_df */ unsigned char bltmp[16]; size_t bltmp_pos; unsigned char KX[48]; } 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. */ struct rand_drbg_st { CRYPTO_RWLOCK *lock; RAND_DRBG *parent; int secure; /* 1: allocated on the secure heap, 0: otherwise */ 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_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 * with respect to how randomness is added to the RNG during reseeding * (see PR #4328). */ struct rand_pool_st *pool; /* * The following parameters are setup by the per-type "init" function. * * Currently the only type is CTR_DRBG, its init function is drbg_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 strength; size_t max_request; 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 DRBG * to its two children, the and 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; /* Application data, mainly used in the KATs. */ CRYPTO_EX_DATA ex_data; /* Implementation specific data (currently only one implementation) */ union { RAND_DRBG_CTR ctr; } data; /* Implementation specific methods */ RAND_DRBG_METHOD *meth; /* Callback functions. See comments in rand_lib.c */ RAND_DRBG_get_entropy_fn get_entropy; RAND_DRBG_cleanup_entropy_fn cleanup_entropy; RAND_DRBG_get_nonce_fn get_nonce; RAND_DRBG_cleanup_nonce_fn cleanup_nonce; }; /* The global RAND method, and the global buffer and DRBG instance. */ extern RAND_METHOD rand_meth; /* * 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 */ int rand_drbg_restart(RAND_DRBG *drbg, const unsigned char *buffer, size_t len, size_t entropy); /* locking api */ int rand_drbg_lock(RAND_DRBG *drbg); int rand_drbg_unlock(RAND_DRBG *drbg); int rand_drbg_enable_locking(RAND_DRBG *drbg); /* initializes the AES-CTR DRBG implementation */ int drbg_ctr_init(RAND_DRBG *drbg); #endif