2a70d65b99
If a nonce is required and the get_nonce callback is NULL, request 50% more entropy following NIST SP800-90Ar1 section 9.1. Reviewed-by: Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> GH: #5503
258 lines
9 KiB
C
258 lines
9 KiB
C
/*
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* Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#ifndef HEADER_RAND_LCL_H
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# define HEADER_RAND_LCL_H
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# include <openssl/aes.h>
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# include <openssl/evp.h>
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# include <openssl/sha.h>
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# include <openssl/hmac.h>
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# include <openssl/ec.h>
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# include <openssl/rand_drbg.h>
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/* How many times to read the TSC as a randomness source. */
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# define TSC_READ_COUNT 4
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/* Maximum reseed intervals */
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# define MAX_RESEED_INTERVAL (1 << 24)
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# define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
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/* Default reseed intervals */
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# define MASTER_RESEED_INTERVAL (1 << 8)
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# define SLAVE_RESEED_INTERVAL (1 << 16)
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# define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
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# define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
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/* Max size of additional input and personalization string. */
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# define DRBG_MAX_LENGTH 4096
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/*
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* The quotient between max_{entropy,nonce}len and min_{entropy,nonce}len
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*
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* The current factor is large enough that the RAND_POOL can store a
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* random input which has a lousy entropy rate of 0.0625 bits per byte.
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* This input will be sent through the derivation function which 'compresses'
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* the low quality input into a high quality output.
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*/
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# define DRBG_MINMAX_FACTOR 128
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/* DRBG status values */
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typedef enum drbg_status_e {
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DRBG_UNINITIALISED,
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DRBG_READY,
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DRBG_ERROR
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} DRBG_STATUS;
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/* intantiate */
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typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
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const unsigned char *ent,
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size_t entlen,
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const unsigned char *nonce,
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size_t noncelen,
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const unsigned char *pers,
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size_t perslen);
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/* reseed */
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typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
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const unsigned char *ent,
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size_t entlen,
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const unsigned char *adin,
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size_t adinlen);
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/* generat output */
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typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
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unsigned char *out,
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size_t outlen,
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const unsigned char *adin,
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size_t adinlen);
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/* uninstantiate */
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typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
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/*
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* The DRBG methods
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*/
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typedef struct rand_drbg_method_st {
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RAND_DRBG_instantiate_fn instantiate;
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RAND_DRBG_reseed_fn reseed;
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RAND_DRBG_generate_fn generate;
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RAND_DRBG_uninstantiate_fn uninstantiate;
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} RAND_DRBG_METHOD;
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/*
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* The state of a DRBG AES-CTR.
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*/
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typedef struct rand_drbg_ctr_st {
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EVP_CIPHER_CTX *ctx;
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EVP_CIPHER_CTX *ctx_df;
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const EVP_CIPHER *cipher;
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size_t keylen;
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unsigned char K[32];
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unsigned char V[16];
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/* Temporary block storage used by ctr_df */
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unsigned char bltmp[16];
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size_t bltmp_pos;
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unsigned char KX[48];
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} RAND_DRBG_CTR;
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/*
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* The 'random pool' acts as a dumb container for collecting random
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* input from various entropy sources. The pool has no knowledge about
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* whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
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* or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
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* random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
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* 4) cleanup the random pool again.
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*
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* The random pool contains no locking mechanism because its scope and
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* lifetime is intended to be restricted to a single stack frame.
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*/
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struct rand_pool_st {
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unsigned char *buffer; /* points to the beginning of the random pool */
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size_t len; /* current number of random bytes contained in the pool */
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size_t min_len; /* minimum number of random bytes requested */
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size_t max_len; /* maximum number of random bytes (allocated buffer size) */
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size_t entropy; /* current entropy count in bits */
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size_t requested_entropy; /* requested entropy count in bits */
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};
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/*
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* The state of all types of DRBGs, even though we only have CTR mode
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* right now.
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*/
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struct rand_drbg_st {
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CRYPTO_RWLOCK *lock;
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RAND_DRBG *parent;
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int secure; /* 1: allocated on the secure heap, 0: otherwise */
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int type; /* the nid of the underlying algorithm */
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/*
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* Stores the value of the rand_fork_count global as of when we last
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* reseeded. The DRG reseeds automatically whenever drbg->fork_count !=
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* rand_fork_count. Used to provide fork-safety and reseed this DRBG in
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* the child process.
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*/
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int fork_count;
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unsigned short flags; /* various external flags */
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/*
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* The random pool is used by RAND_add()/drbg_add() to attach random
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* data to the global drbg, such that the rand_drbg_get_entropy() callback
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* can pull it during instantiation and reseeding. This is necessary to
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* reconcile the different philosophies of the RAND and the RAND_DRBG
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* with respect to how randomness is added to the RNG during reseeding
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* (see PR #4328).
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*/
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struct rand_pool_st *pool;
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/*
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* The following parameters are setup by the per-type "init" function.
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*
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* Currently the only type is CTR_DRBG, its init function is drbg_ctr_init().
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*
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* The parameters are closely related to the ones described in
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* section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
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* crucial difference: In the NIST standard, all counts are given
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* in bits, whereas in OpenSSL entropy counts are given in bits
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* and buffer lengths are given in bytes.
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*
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* Since this difference has lead to some confusion in the past,
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* (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
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* the 'len' suffix has been added to all buffer sizes for
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* clarification.
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*/
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int strength;
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size_t max_request;
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size_t min_entropylen, max_entropylen;
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size_t min_noncelen, max_noncelen;
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size_t max_perslen, max_adinlen;
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/* Counts the number of generate requests since the last reseed. */
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unsigned int generate_counter;
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/*
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* Maximum number of generate requests until a reseed is required.
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* This value is ignored if it is zero.
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*/
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unsigned int reseed_interval;
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/* Stores the time when the last reseeding occurred */
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time_t reseed_time;
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/*
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* Specifies the maximum time interval (in seconds) between reseeds.
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* This value is ignored if it is zero.
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*/
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time_t reseed_time_interval;
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/*
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* Counts the number of reseeds since instantiation.
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* This value is ignored if it is zero.
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*
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* This counter is used only for seed propagation from the <master> DRBG
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* to its two children, the <public> and <private> DRBG. This feature is
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* very special and its sole purpose is to ensure that any randomness which
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* is added by RAND_add() or RAND_seed() will have an immediate effect on
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* the output of RAND_bytes() resp. RAND_priv_bytes().
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*/
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unsigned int reseed_counter;
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size_t seedlen;
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DRBG_STATUS state;
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/* Application data, mainly used in the KATs. */
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CRYPTO_EX_DATA ex_data;
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/* Implementation specific data (currently only one implementation) */
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union {
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RAND_DRBG_CTR ctr;
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} data;
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/* Implementation specific methods */
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RAND_DRBG_METHOD *meth;
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/* Callback functions. See comments in rand_lib.c */
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RAND_DRBG_get_entropy_fn get_entropy;
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RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
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RAND_DRBG_get_nonce_fn get_nonce;
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RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
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};
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/* The global RAND method, and the global buffer and DRBG instance. */
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extern RAND_METHOD rand_meth;
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/*
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* A "generation count" of forks. Incremented in the child process after a
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* fork. Since rand_fork_count is increment-only, and only ever written to in
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* the child process of the fork, which is guaranteed to be single-threaded, no
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* locking is needed for normal (read) accesses; the rest of pthread fork
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* processing is assumed to introduce the necessary memory barriers. Sibling
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* children of a given parent will produce duplicate values, but this is not
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* problematic because the reseeding process pulls input from the system CSPRNG
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* and/or other global sources, so the siblings will end up generating
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* different output streams.
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*/
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extern int rand_fork_count;
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/* DRBG helpers */
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int rand_drbg_restart(RAND_DRBG *drbg,
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const unsigned char *buffer, size_t len, size_t entropy);
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/* locking api */
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int rand_drbg_lock(RAND_DRBG *drbg);
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int rand_drbg_unlock(RAND_DRBG *drbg);
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int rand_drbg_enable_locking(RAND_DRBG *drbg);
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/* initializes the AES-CTR DRBG implementation */
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int drbg_ctr_init(RAND_DRBG *drbg);
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#endif
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