text: /*
   * Copyright 1995-2018 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
   */
  
  #ifndef OSSL_CRYPTO_RAND_LOCAL_H
  # define OSSL_CRYPTO_RAND_LOCAL_H
  
  # include <openssl/aes.h>
  # include <openssl/evp.h>
  # include <openssl/sha.h>
  # include <openssl/hmac.h>
  # include <openssl/ec.h>
  # include <openssl/rand_drbg.h>
  # include "internal/tsan_assist.h"
  # include "crypto/rand.h"
  
  # 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 */
  
  /*
   * The number of bytes that constitutes an atomic lump of entropy with respect
   * to the FIPS 140-2 section 4.9.2 Conditional Tests.  The size is somewhat
   * arbitrary, the smaller the value, the less entropy is consumed on first
   * read but the higher the probability of the test failing by accident.
   *
   * The value is in bytes.
   */
  #define CRNGT_BUFSIZ    16
  
  /*
   * 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 default nonce */
  #ifdef CHARSET_EBCDIC
  # define DRBG_DEFAULT_PERS_STRING      { 0x4f, 0x70, 0x65, 0x6e, 0x53, 0x53, \
       0x4c, 0x20, 0x4e, 0x49, 0x53, 0x54, 0x20, 0x53, 0x50, 0x20, 0x38, 0x30, \
       0x30, 0x2d, 0x39, 0x30, 0x41, 0x20, 0x44, 0x52, 0x42, 0x47, 0x00};
  #else
  # define DRBG_DEFAULT_PERS_STRING                "OpenSSL NIST SP 800-90A DRBG"
  #endif
  
  /*
   * 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))
   */
  
  /*
   * Initial allocation minimum.
   *
   * There is a distinction between the secure and normal allocation minimums.
   * Ideally, the secure allocation size should be a power of two.  The normal
   * allocation size doesn't have any such restriction.
   *
   * The secure value is based on 128 bits of secure material, which is 16 bytes.
   * Typically, the DRBGs will set a minimum larger than this so optimal
   * allocation ought to take place (for full quality seed material).
   *
   * The normal value has been chosed by noticing that the rand_drbg_get_nonce
   * function is usually the largest of the built in allocation (twenty four
   * bytes and then appending another sixteen bytes).  This means the buffer ends
   * with 40 bytes.  The value of forty eight is comfortably above this which
   * allows some slack in the platform specific values used.
   */
  # define RAND_POOL_MIN_ALLOCATION(secure) ((secure) ? 16 : 48)
  
  /* DRBG status values */
  typedef enum drbg_status_e {
      DRBG_UNINITIALISED,
      DRBG_READY,
      DRBG_ERROR
  } DRBG_STATUS;
  
  
  /* instantiate */
  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);
  /* generate 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;
  
  /* 888 bits from SP800-90Ar1 10.1 table 2 */
  #define HASH_PRNG_MAX_SEEDLEN    (888/8)
  
  typedef struct rand_drbg_hash_st {
      EVP_MD *md;
      EVP_MD_CTX *ctx;
      size_t blocklen;
      unsigned char V[HASH_PRNG_MAX_SEEDLEN];
      unsigned char C[HASH_PRNG_MAX_SEEDLEN];
      /* Temporary value storage: should always exceed max digest length */
      unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
  } RAND_DRBG_HASH;
  
  typedef struct rand_drbg_hmac_st {
      EVP_MD *md;
      HMAC_CTX *ctx;
      size_t blocklen;
      unsigned char K[EVP_MAX_MD_SIZE];
      unsigned char V[EVP_MAX_MD_SIZE];
  } RAND_DRBG_HMAC;
  
  /*
   * The state of a DRBG AES-CTR.
   */
  typedef struct rand_drbg_ctr_st {
      EVP_CIPHER_CTX *ctx;
      EVP_CIPHER_CTX *ctx_df;
      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 */
      int secure;    /* 1: allocated on the secure heap, 0: otherwise */
  
      size_t min_len; /* minimum number of random bytes requested */
      size_t max_len; /* maximum number of random bytes (allocated buffer size) */
      size_t alloc_len; /* current number of bytes allocated */
      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;
      /* The library context this DRBG is associated with, if any */
      OPENSSL_CTX *libctx;
      RAND_DRBG *parent;
      int secure; /* 1: allocated on the secure heap, 0: otherwise */
      int type; /* the nid of the underlying algorithm */
      /*
       * Stores the return value of openssl_get_fork_id() as of when we last
       * reseeded.  The DRBG reseeds automatically whenever drbg->fork_id !=
       * openssl_get_fork_id().  Used to provide fork-safety and reseed this
       * DRBG in the child process.
       */
      int fork_id;
      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 *seed_pool;
  
      /*
       * Auxiliary pool for additional data.
       */
      struct rand_pool_st *adin_pool;
  
      /*
       * The following parameters are setup by the per-type "init" function.
       *
       * The supported types and their init functions are:
       *    (1) CTR_DRBG:  drbg_ctr_init().
       *    (2) HMAC_DRBG: drbg_hmac_init().
       *    (3) HASH_DRBG: drbg_hash_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
       * (Starts at 1). This value is the reseed_counter as defined in
       * NIST SP 800-90Ar1
       */
      unsigned int reseed_gen_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 <master> DRBG
       * to its two children, the <public> and <private> 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().
       */
      TSAN_QUALIFIER unsigned int reseed_prop_counter;
      unsigned int reseed_next_counter;
  
      size_t seedlen;
      DRBG_STATUS state;
  
      /* Application data, mainly used in the KATs. */
      CRYPTO_EX_DATA ex_data;
  
      /* Implementation specific data */
      union {
          RAND_DRBG_CTR ctr;
          RAND_DRBG_HASH hash;
          RAND_DRBG_HMAC hmac;
      } 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;
  
  /* DRBG helpers */
  int rand_drbg_restart(RAND_DRBG *drbg,
                        const unsigned char *buffer, size_t len, size_t entropy);
  size_t rand_drbg_seedlen(RAND_DRBG *drbg);
  /* 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 DRBG implementation */
  int drbg_ctr_init(RAND_DRBG *drbg);
  int drbg_hash_init(RAND_DRBG *drbg);
  int drbg_hmac_init(RAND_DRBG *drbg);
  
  /*
   * Entropy call back for the FIPS 140-2 section 4.9.2 Conditional Tests.
   * These need to be exposed for the unit tests.
   */
  int rand_crngt_get_entropy_cb(OPENSSL_CTX *ctx, RAND_POOL *pool,
                                unsigned char *buf, unsigned char *md,
                                unsigned int *md_size);
  extern int (*crngt_get_entropy)(OPENSSL_CTX *ctx, RAND_POOL *pool,
                                  unsigned char *buf, unsigned char *md,
                                  unsigned int *md_size);
  
  #endif
  