/*

 * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (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

 */

/*

 * Licensed under the Apache License 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 * https://www.openssl.org/source/license.html

 * or in the file LICENSE in the source distribution.

 */

#ifndef OSSL_CRYPTO_RAND_H

# define OSSL_CRYPTO_RAND_H

# include <openssl/rand.h>

/* forward declaration */

typedef struct rand_pool_st RAND_POOL;

/*

 * Defines related to seed sources

 */

#ifndef DEVRANDOM

/*

 * set this to a comma-separated list of 'random' device files to try out. By

 * default, we will try to read at least one of these files

 */

# define DEVRANDOM "/dev/urandom", "/dev/random", "/dev/hwrng", "/dev/srandom"

# if defined(__linux) && !defined(__ANDROID__)

#  ifndef DEVRANDOM_WAIT

#   define DEVRANDOM_WAIT   "/dev/random"

#  endif

/*

 * Linux kernels 4.8 and later changes how their random device works and there

 * is no reliable way to tell that /dev/urandom has been seeded -- getentropy(2)

 * should be used instead.

 */

#  ifndef DEVRANDOM_SAFE_KERNEL

#   define DEVRANDOM_SAFE_KERNEL        4, 8

#  endif

/*

 * Some operating systems do not permit select(2) on their random devices,

 * defining this to zero will force the use of read(2) to extract one byte

 * from /dev/random.

 */

#  ifndef DEVRANDM_WAIT_USE_SELECT

#   define DEVRANDM_WAIT_USE_SELECT     1

#  endif

/*

 * Define the shared memory identifier used to indicate if the operating

 * system has properly seeded the DEVRANDOM source.

 */

#  ifndef OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID

#   define OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID 114

#  endif

# endif

#endif

#if !defined(OPENSSL_NO_EGD) && !defined(DEVRANDOM_EGD)

/*

 * set this to a comma-separated list of 'egd' sockets to try out. These

 * sockets will be tried in the order listed in case accessing the device

 * files listed in DEVRANDOM did not return enough randomness.

 */

# define DEVRANDOM_EGD "/var/run/egd-pool", "/dev/egd-pool", "/etc/egd-pool", "/etc/entropy"

#endif

void rand_cleanup_int(void);

/* Hardware-based seeding functions. */

size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool);

size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool);

/* DRBG entropy callbacks. */

size_t rand_drbg_get_entropy(RAND_DRBG *drbg,

                             unsigned char **pout,

                             int entropy, size_t min_len, size_t max_len,

                             int prediction_resistance);

void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,

                               unsigned char *out, size_t outlen);

size_t rand_drbg_get_nonce(RAND_DRBG *drbg,

                           unsigned char **pout,

                           int entropy, size_t min_len, size_t max_len);

void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,

                             unsigned char *out, size_t outlen);

size_t rand_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout);

void rand_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out);

/* CRNG test entropy filter callbacks. */

size_t rand_crngt_get_entropy(RAND_DRBG *drbg,

                              unsigned char **pout,

                              int entropy, size_t min_len, size_t max_len,

                              int prediction_resistance);

void rand_crngt_cleanup_entropy(RAND_DRBG *drbg,

                                unsigned char *out, size_t outlen);

/*

 * RAND_POOL functions

 */

RAND_POOL *rand_pool_new(int entropy_requested, int secure,

                         size_t min_len, size_t max_len);

RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,

                            size_t entropy);

void rand_pool_free(RAND_POOL *pool);

const unsigned char *rand_pool_buffer(RAND_POOL *pool);

unsigned char *rand_pool_detach(RAND_POOL *pool);

void rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer);

size_t rand_pool_entropy(RAND_POOL *pool);

size_t rand_pool_length(RAND_POOL *pool);

size_t rand_pool_entropy_available(RAND_POOL *pool);

size_t rand_pool_entropy_needed(RAND_POOL *pool);

/* |entropy_factor| expresses how many bits of data contain 1 bit of entropy */

size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor);

size_t rand_pool_bytes_remaining(RAND_POOL *pool);

int rand_pool_add(RAND_POOL *pool,

                  const unsigned char *buffer, size_t len, size_t entropy);

unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len);

int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy);

/*

 * Add random bytes to the pool to acquire requested amount of entropy

 *

 * This function is platform specific and tries to acquire the requested

 * amount of entropy by polling platform specific entropy sources.

 *

 * If the function succeeds in acquiring at least |entropy_requested| bits

 * of entropy, the total entropy count is returned. If it fails, it returns

 * an entropy count of 0.

 */

size_t rand_pool_acquire_entropy(RAND_POOL *pool);

/*

 * Add some application specific nonce data

 *

 * This function is platform specific and adds some application specific

 * data to the nonce used for instantiating the drbg.

 *

 * This data currently consists of the process and thread id, and a high

 * resolution timestamp. The data does not include an atomic counter,

 * because that is added by the calling function rand_drbg_get_nonce().

 *

 * Returns 1 on success and 0 on failure.

 */

int rand_pool_add_nonce_data(RAND_POOL *pool);

/*

 * Add some platform specific additional data

 *

 * This function is platform specific and adds some random noise to the

 * additional data used for generating random bytes and for reseeding

 * the drbg.

 *

 * Returns 1 on success and 0 on failure.

 */

int rand_pool_add_additional_data(RAND_POOL *pool);

/*

 * Initialise the random pool reseeding sources.

 *

 * Returns 1 on success and 0 on failure.

 */

int rand_pool_init(void);

/*

 * Finalise the random pool reseeding sources.

 */

void rand_pool_cleanup(void);

/*

 * Control the random pool use of open file descriptors.

 */

void rand_pool_keep_random_devices_open(int keep);

#endif