/* * Copyright 2011-2018 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 */ #include #include #include #include #include "rand_lcl.h" #include "internal/thread_once.h" #include "internal/rand_int.h" /* * Support framework for NIST SP 800-90A DRBG, AES-CTR mode. * The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG. * * The OpenSSL model is to have new and free functions, and that new * does all initialization. That is not the NIST model, which has * instantiation and un-instantiate, and re-use within a new/free * lifecycle. (No doubt this comes from the desire to support hardware * DRBG, where allocation of resources on something like an HSM is * a much bigger deal than just re-setting an allocated resource.) */ /* * THE THREE SHARED DRBGs * * There are three shared DRBGs (master, public and private), which are * accessed concurrently by all threads. * * THE MASTER DRBG * * Not used directly by the application, only for reseeding the two other * DRBGs. It reseeds itself by pulling either randomness from os entropy * sources or by consuming randomnes which was added by RAND_add() */ static RAND_DRBG *drbg_master; /* * THE PUBLIC DRBG * * Used by default for generating random bytes using RAND_bytes(). */ static RAND_DRBG *drbg_public; /* * THE PRIVATE DRBG * * Used by default for generating private keys using RAND_priv_bytes() */ static RAND_DRBG *drbg_private; /*+ * DRBG HIERARCHY * * In addition there are DRBGs, which are not shared, but used only by a * single thread at every time, for example the DRBGs which are owned by * an SSL context. All DRBGs are organized in a hierarchical fashion * with the DRBG as root. * * This gives the following overall picture: * * * | * RAND_add() ==> \ * / \ | shared DRBGs (with locking) * / * | * owned by an SSL context * * AUTOMATIC RESEEDING * * Before satisfying a generate request, a DRBG reseeds itself automatically, * if one of the following two conditions holds: * * - the number of generate requests since the last reseeding exceeds a * certain threshold, the so called |reseed_interval|. This behaviour * can be disabled by setting the |reseed_interval| to 0. * * - the time elapsed since the last reseeding exceeds a certain time * interval, the so called |reseed_time_interval|. This behaviour * can be disabled by setting the |reseed_time_interval| to 0. * * MANUAL RESEEDING * * For the three shared DRBGs (and only for these) there is another way to * reseed them manually by calling RAND_seed() (or RAND_add() with a positive * |randomness| argument). This will immediately reseed the DRBG. * The and DRBG will detect this on their next generate * call and reseed, pulling randomness from . * * LOCKING * * The three shared DRBGs are intended to be used concurrently, so they * support locking by default. It is the callers responsibility to wrap * calls to functions like RAND_DRBG_generate() which modify the DRBGs * internal state with calls to RAND_DRBG_lock() and RAND_DRBG_unlock(). * The functions RAND_bytes() and RAND_priv_bytes() take the locks * automatically, so using the RAND api is thread safe as before. * * All other DRBG instances don't have locking enabled by default, because * they are intendended to be used by a single thread. If it is desired, * locking can be enabled using RAND_DRBG_enable_locking(). However, instead * of accessing a single DRBG instance concurrently from different threads, * it is recommended to instantiate a separate DRBG instance per thread. */ /* NIST SP 800-90A DRBG recommends the use of a personalization string. */ static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG"; static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT; static RAND_DRBG *drbg_setup(RAND_DRBG *parent); static RAND_DRBG *rand_drbg_new(int secure, int type, unsigned int flags, RAND_DRBG *parent); /* * Set/initialize |drbg| to be of type |nid|, with optional |flags|. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_set(RAND_DRBG *drbg, int nid, unsigned int flags) { int ret = 1; drbg->state = DRBG_UNINITIALISED; drbg->flags = flags; drbg->nid = nid; switch (nid) { default: RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE); return 0; case 0: /* Uninitialized; that's okay. */ return 1; case NID_aes_128_ctr: case NID_aes_192_ctr: case NID_aes_256_ctr: ret = drbg_ctr_init(drbg); break; } if (ret == 0) RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG); return ret; } /* * Allocate memory and initialize a new DRBG. The DRBG is allocated on * the secure heap if |secure| is nonzero and the secure heap is enabled. * The |parent|, if not NULL, will be used as random source for reseeding. * * Returns a pointer to the new DRBG instance on success, NULL on failure. */ static RAND_DRBG *rand_drbg_new(int secure, int type, unsigned int flags, RAND_DRBG *parent) { RAND_DRBG *drbg = secure ? OPENSSL_secure_zalloc(sizeof(*drbg)) : OPENSSL_zalloc(sizeof(*drbg)); if (drbg == NULL) { RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE); goto err; } drbg->secure = secure && CRYPTO_secure_allocated(drbg); drbg->fork_count = rand_fork_count; drbg->parent = parent; if (RAND_DRBG_set(drbg, type, flags) == 0) goto err; if (!RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy, rand_drbg_cleanup_entropy, NULL, NULL)) goto err; return drbg; err: if (drbg->secure) OPENSSL_secure_free(drbg); else OPENSSL_free(drbg); return NULL; } RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent) { return rand_drbg_new(0, type, flags, parent); } RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent) { return rand_drbg_new(1, type, flags, parent); } /* * Uninstantiate |drbg| and free all memory. */ void RAND_DRBG_free(RAND_DRBG *drbg) { if (drbg == NULL) return; if (drbg->meth != NULL) drbg->meth->uninstantiate(drbg); CRYPTO_THREAD_lock_free(drbg->lock); CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data); if (drbg->secure) OPENSSL_secure_clear_free(drbg, sizeof(*drbg)); else OPENSSL_clear_free(drbg, sizeof(*drbg)); } /* * Instantiate |drbg|, after it has been initialized. Use |pers| and * |perslen| as prediction-resistance input. * * Requires that drbg->lock is already locked for write, if non-null. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_instantiate(RAND_DRBG *drbg, const unsigned char *pers, size_t perslen) { unsigned char *nonce = NULL, *entropy = NULL; size_t noncelen = 0, entropylen = 0; if (perslen > drbg->max_perslen) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_PERSONALISATION_STRING_TOO_LONG); goto end; } if (drbg->meth == NULL) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED); goto end; } if (drbg->state != DRBG_UNINITIALISED) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE : RAND_R_ALREADY_INSTANTIATED); goto end; } drbg->state = DRBG_ERROR; if (drbg->get_entropy != NULL) entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength, drbg->min_entropylen, drbg->max_entropylen); if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY); goto end; } if (drbg->max_noncelen > 0 && drbg->get_nonce != NULL) { noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2, drbg->min_noncelen, drbg->max_noncelen); if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE); goto end; } } if (!drbg->meth->instantiate(drbg, entropy, entropylen, nonce, noncelen, pers, perslen)) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG); goto end; } drbg->state = DRBG_READY; drbg->generate_counter = 0; drbg->reseed_time = time(NULL); if (drbg->reseed_counter > 0) { if (drbg->parent == NULL) drbg->reseed_counter++; else drbg->reseed_counter = drbg->parent->reseed_counter; } end: if (entropy != NULL && drbg->cleanup_entropy != NULL) drbg->cleanup_entropy(drbg, entropy, entropylen); if (nonce != NULL && drbg->cleanup_nonce!= NULL ) drbg->cleanup_nonce(drbg, nonce, noncelen); if (drbg->pool != NULL) { if (drbg->state == DRBG_READY) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_ENTROPY_POOL_WAS_IGNORED); drbg->state = DRBG_ERROR; } RAND_POOL_free(drbg->pool); drbg->pool = NULL; } if (drbg->state == DRBG_READY) return 1; return 0; } /* * Uninstantiate |drbg|. Must be instantiated before it can be used. * * Requires that drbg->lock is already locked for write, if non-null. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_uninstantiate(RAND_DRBG *drbg) { if (drbg->meth == NULL) { RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE, RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED); return 0; } /* Clear the entire drbg->ctr struct, then reset some important * members of the drbg->ctr struct (e.g. keysize, df_ks) to their * initial values. */ drbg->meth->uninstantiate(drbg); return RAND_DRBG_set(drbg, drbg->nid, drbg->flags); } /* * Reseed |drbg|, mixing in the specified data * * Requires that drbg->lock is already locked for write, if non-null. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_reseed(RAND_DRBG *drbg, const unsigned char *adin, size_t adinlen) { unsigned char *entropy = NULL; size_t entropylen = 0; if (drbg->state == DRBG_ERROR) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE); return 0; } if (drbg->state == DRBG_UNINITIALISED) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED); return 0; } if (adin == NULL) adinlen = 0; else if (adinlen > drbg->max_adinlen) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG); return 0; } drbg->state = DRBG_ERROR; if (drbg->get_entropy != NULL) entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength, drbg->min_entropylen, drbg->max_entropylen); if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY); goto end; } if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen)) goto end; drbg->state = DRBG_READY; drbg->generate_counter = 0; drbg->reseed_time = time(NULL); if (drbg->reseed_counter > 0) { if (drbg->parent == NULL) drbg->reseed_counter++; else drbg->reseed_counter = drbg->parent->reseed_counter; } end: if (entropy != NULL && drbg->cleanup_entropy != NULL) drbg->cleanup_entropy(drbg, entropy, entropylen); if (drbg->state == DRBG_READY) return 1; return 0; } /* * Restart |drbg|, using the specified entropy or additional input * * Tries its best to get the drbg instantiated by all means, * regardless of its current state. * * Optionally, a |buffer| of |len| random bytes can be passed, * which is assumed to contain at least |entropy| bits of entropy. * * If |entropy| > 0, the buffer content is used as entropy input. * * If |entropy| == 0, the buffer content is used as additional input * * Returns 1 on success, 0 on failure. * * This function is used internally only. */ int rand_drbg_restart(RAND_DRBG *drbg, const unsigned char *buffer, size_t len, size_t entropy) { int reseeded = 0; const unsigned char *adin = NULL; size_t adinlen = 0; if (drbg->pool != NULL) { RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR); RAND_POOL_free(drbg->pool); drbg->pool = NULL; } if (buffer != NULL) { if (entropy > 0) { if (drbg->max_entropylen < len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_INPUT_TOO_LONG); return 0; } if (entropy > 8 * len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE); return 0; } /* will be picked up by the rand_drbg_get_entropy() callback */ drbg->pool = RAND_POOL_new(entropy, len, len); if (drbg->pool == NULL) return 0; RAND_POOL_add(drbg->pool, buffer, len, entropy); } else { if (drbg->max_adinlen < len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ADDITIONAL_INPUT_TOO_LONG); return 0; } adin = buffer; adinlen = len; } } /* repair error state */ if (drbg->state == DRBG_ERROR) RAND_DRBG_uninstantiate(drbg); /* repair uninitialized state */ if (drbg->state == DRBG_UNINITIALISED) { /* reinstantiate drbg */ RAND_DRBG_instantiate(drbg, (const unsigned char *) ossl_pers_string, sizeof(ossl_pers_string) - 1); /* already reseeded. prevent second reseeding below */ reseeded = (drbg->state == DRBG_READY); } /* refresh current state if entropy or additional input has been provided */ if (drbg->state == DRBG_READY) { if (adin != NULL) { /* * mix in additional input without reseeding * * Similar to RAND_DRBG_reseed(), but the provided additional * data |adin| is mixed into the current state without pulling * entropy from the trusted entropy source using get_entropy(). * This is not a reseeding in the strict sense of NIST SP 800-90A. */ drbg->meth->reseed(drbg, adin, adinlen, NULL, 0); } else if (reseeded == 0) { /* do a full reseeding if it has not been done yet above */ RAND_DRBG_reseed(drbg, NULL, 0); } } /* check whether a given entropy pool was cleared properly during reseed */ if (drbg->pool != NULL) { drbg->state = DRBG_ERROR; RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR); RAND_POOL_free(drbg->pool); drbg->pool = NULL; return 0; } return drbg->state == DRBG_READY; } /* * Generate |outlen| bytes into the buffer at |out|. Reseed if we need * to or if |prediction_resistance| is set. Additional input can be * sent in |adin| and |adinlen|. * * Requires that drbg->lock is already locked for write, if non-null. * * Returns 1 on success, 0 on failure. * */ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen, int prediction_resistance, const unsigned char *adin, size_t adinlen) { int reseed_required = 0; if (drbg->state != DRBG_READY) { /* try to recover from previous errors */ rand_drbg_restart(drbg, NULL, 0, 0); if (drbg->state == DRBG_ERROR) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE); return 0; } if (drbg->state == DRBG_UNINITIALISED) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED); return 0; } } if (outlen > drbg->max_request) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG); return 0; } if (adinlen > drbg->max_adinlen) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG); return 0; } if (drbg->fork_count != rand_fork_count) { drbg->fork_count = rand_fork_count; reseed_required = 1; } if (drbg->reseed_interval > 0) { if (drbg->generate_counter >= drbg->reseed_interval) reseed_required = 1; } if (drbg->reseed_time_interval > 0) { time_t now = time(NULL); if (now < drbg->reseed_time || now - drbg->reseed_time >= drbg->reseed_time_interval) reseed_required = 1; } if (drbg->reseed_counter > 0 && drbg->parent != NULL) { if (drbg->reseed_counter != drbg->parent->reseed_counter) reseed_required = 1; } if (reseed_required || prediction_resistance) { if (!RAND_DRBG_reseed(drbg, adin, adinlen)) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR); return 0; } adin = NULL; adinlen = 0; } if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) { drbg->state = DRBG_ERROR; RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR); return 0; } drbg->generate_counter++; return 1; } /* * Generates |outlen| random bytes and stores them in |out|. It will * using the given |drbg| to generate the bytes. * * Requires that drbg->lock is already locked for write, if non-null. * * Returns 1 on success 0 on failure. */ int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen) { unsigned char *additional = NULL; size_t additional_len; size_t chunk; size_t ret; additional_len = rand_drbg_get_additional_data(&additional, drbg->max_adinlen); for ( ; outlen > 0; outlen -= chunk, out += chunk) { chunk = outlen; if (chunk > drbg->max_request) chunk = drbg->max_request; ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len); if (!ret) goto err; } ret = 1; err: if (additional_len != 0) OPENSSL_secure_clear_free(additional, additional_len); return ret; } /* * Set the RAND_DRBG callbacks for obtaining entropy and nonce. * * In the following, the signature and the semantics of the * get_entropy() and cleanup_entropy() callbacks are explained. * * GET_ENTROPY * * size_t get_entropy(RAND_DRBG *ctx, * unsigned char **pout, * int entropy, * size_t min_len, size_t max_len); * * This is a request to allocate and fill a buffer of size * |min_len| <= size <= |max_len| (in bytes) which contains * at least |entropy| bits of randomness. The buffer's address is * to be returned in |*pout| and the number of collected * randomness bytes (which may be less than the allocated size * of the buffer) as return value. * * If the callback fails to acquire at least |entropy| bits of * randomness, it shall return a buffer length of 0. * * CLEANUP_ENTROPY * * void cleanup_entropy(RAND_DRBG *ctx, * unsigned char *out, size_t outlen); * * A request to clear and free the buffer allocated by get_entropy(). * The values |out| and |outlen| are expected to be the random buffer's * address and length, as returned by the get_entropy() callback. * * GET_NONCE, CLEANUP_NONCE * * Signature and semantics of the get_nonce() and cleanup_nonce() * callbacks are analogous to get_entropy() and cleanup_entropy(). * Currently, the nonce is used only for the known answer tests. */ int RAND_DRBG_set_callbacks(RAND_DRBG *drbg, 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) { if (drbg->state != DRBG_UNINITIALISED) return 0; drbg->get_entropy = get_entropy; drbg->cleanup_entropy = cleanup_entropy; drbg->get_nonce = get_nonce; drbg->cleanup_nonce = cleanup_nonce; return 1; } /* * Set the reseed interval. * * The drbg will reseed automatically whenever the number of generate * requests exceeds the given reseed interval. If the reseed interval * is 0, then this feature is disabled. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval) { if (interval > MAX_RESEED_INTERVAL) return 0; drbg->reseed_interval = interval; return 1; } /* * Set the reseed time interval. * * The drbg will reseed automatically whenever the time elapsed since * the last reseeding exceeds the given reseed time interval. For safety, * a reseeding will also occur if the clock has been reset to a smaller * value. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval) { if (interval > MAX_RESEED_TIME_INTERVAL) return 0; drbg->reseed_time_interval = interval; return 1; } /* * Locks the given drbg. Locking a drbg which does not have locking * enabled is considered a successful no-op. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_lock(RAND_DRBG *drbg) { if (drbg->lock != NULL) return CRYPTO_THREAD_write_lock(drbg->lock); return 1; } /* * Unlocks the given drbg. Unlocking a drbg which does not have locking * enabled is considered a successful no-op. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_unlock(RAND_DRBG *drbg) { if (drbg->lock != NULL) return CRYPTO_THREAD_unlock(drbg->lock); return 1; } /* * Enables locking for the given drbg * * Locking can only be enabled if the random generator * is in the uninitialized state. * * Returns 1 on success, 0 on failure. */ int RAND_DRBG_enable_locking(RAND_DRBG *drbg) { if (drbg->state != DRBG_UNINITIALISED) { RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING, RAND_R_DRBG_ALREADY_INITIALIZED); return 0; } if (drbg->lock == NULL) { if (drbg->parent != NULL && drbg->parent->lock == NULL) { RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING, RAND_R_PARENT_LOCKING_NOT_ENABLED); return 0; } drbg->lock = CRYPTO_THREAD_lock_new(); if (drbg->lock == NULL) { RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING, RAND_R_FAILED_TO_CREATE_LOCK); return 0; } } return 1; } /* * Get and set the EXDATA */ int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg) { return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg); } void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx) { return CRYPTO_get_ex_data(&drbg->ex_data, idx); } /* * The following functions provide a RAND_METHOD that works on the * global DRBG. They lock. */ /* * Allocates a new global DRBG on the secure heap (if enabled) and * initializes it with default settings. * * Returns a pointer to the new DRBG instance on success, NULL on failure. */ static RAND_DRBG *drbg_setup(RAND_DRBG *parent) { RAND_DRBG *drbg; drbg = RAND_DRBG_secure_new(RAND_DRBG_NID, RAND_DRBG_FLAG_CTR_USE_DF, parent); if (drbg == NULL) return NULL; if (RAND_DRBG_enable_locking(drbg) == 0) goto err; if (parent == NULL) { drbg->reseed_interval = MASTER_RESEED_INTERVAL; drbg->reseed_time_interval = MASTER_RESEED_TIME_INTERVAL; } else { drbg->reseed_interval = SLAVE_RESEED_INTERVAL; drbg->reseed_time_interval = SLAVE_RESEED_TIME_INTERVAL; } /* enable seed propagation */ drbg->reseed_counter = 1; /* * Ignore instantiation error so support just-in-time instantiation. * * The state of the drbg will be checked in RAND_DRBG_generate() and * an automatic recovery is attempted. */ RAND_DRBG_instantiate(drbg, (const unsigned char *) ossl_pers_string, sizeof(ossl_pers_string) - 1); return drbg; err: RAND_DRBG_free(drbg); return NULL; } /* * Initialize the global DRBGs on first use. * Returns 1 on success, 0 on failure. */ DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init) { /* * ensure that libcrypto is initialized, otherwise the * DRBG locks are not cleaned up properly */ if (!OPENSSL_init_crypto(0, NULL)) return 0; drbg_master = drbg_setup(NULL); drbg_public = drbg_setup(drbg_master); drbg_private = drbg_setup(drbg_master); if (drbg_master == NULL || drbg_public == NULL || drbg_private == NULL) return 0; return 1; } /* Clean up the global DRBGs before exit */ void rand_drbg_cleanup_int(void) { RAND_DRBG_free(drbg_private); RAND_DRBG_free(drbg_public); RAND_DRBG_free(drbg_master); drbg_private = drbg_public = drbg_master = NULL; } /* Implements the default OpenSSL RAND_bytes() method */ static int drbg_bytes(unsigned char *out, int count) { int ret; RAND_DRBG *drbg = RAND_DRBG_get0_public(); if (drbg == NULL) return 0; RAND_DRBG_lock(drbg); ret = RAND_DRBG_bytes(drbg, out, count); RAND_DRBG_unlock(drbg); return ret; } /* Implements the default OpenSSL RAND_add() method */ static int drbg_add(const void *buf, int num, double randomness) { int ret = 0; RAND_DRBG *drbg = RAND_DRBG_get0_master(); if (drbg == NULL) return 0; if (num < 0 || randomness < 0.0) return 0; if (randomness > (double)drbg->max_entropylen) { /* * The purpose of this check is to bound |randomness| by a * relatively small value in order to prevent an integer * overflow when multiplying by 8 in the rand_drbg_restart() * call below. */ return 0; } RAND_DRBG_lock(drbg); ret = rand_drbg_restart(drbg, buf, (size_t)(unsigned int)num, (size_t)(8*randomness)); RAND_DRBG_unlock(drbg); return ret; } /* Implements the default OpenSSL RAND_seed() method */ static int drbg_seed(const void *buf, int num) { return drbg_add(buf, num, num); } /* Implements the default OpenSSL RAND_status() method */ static int drbg_status(void) { int ret; RAND_DRBG *drbg = RAND_DRBG_get0_master(); if (drbg == NULL) return 0; RAND_DRBG_lock(drbg); ret = drbg->state == DRBG_READY ? 1 : 0; RAND_DRBG_unlock(drbg); return ret; } /* * Get the master DRBG. * Returns pointer to the DRBG on success, NULL on failure. * */ RAND_DRBG *RAND_DRBG_get0_master(void) { if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init)) return NULL; return drbg_master; } /* * Get the public DRBG. * Returns pointer to the DRBG on success, NULL on failure. */ RAND_DRBG *RAND_DRBG_get0_public(void) { if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init)) return NULL; return drbg_public; } /* * Get the private DRBG. * Returns pointer to the DRBG on success, NULL on failure. */ RAND_DRBG *RAND_DRBG_get0_private(void) { if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init)) return NULL; return drbg_private; } RAND_METHOD rand_meth = { drbg_seed, drbg_bytes, NULL, drbg_add, drbg_bytes, drbg_status }; RAND_METHOD *RAND_OpenSSL(void) { return &rand_meth; }