include/crypto/rng.h

   1 /*
   2  * RNG: Random Number Generator  algorithms under the crypto API
   3  *
   4  * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  */
  12
  13 #ifndef _CRYPTO_RNG_H
  14 #define _CRYPTO_RNG_H
  15
  16 #include <linux/crypto.h>
  17
  18 struct crypto_rng {
  19         int (*generate)(struct crypto_rng *tfm,
  20                         const u8 *src, unsigned int slen,
  21                         u8 *dst, unsigned int dlen);
  22         int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
  23         struct crypto_tfm base;
  24 };
  25
  26 extern struct crypto_rng *crypto_default_rng;
  27
  28 int crypto_get_default_rng(void);
  29 void crypto_put_default_rng(void);
  30
  31 /**
  32  * DOC: Random number generator API
  33  *
  34  * The random number generator API is used with the ciphers of type
  35  * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)
  36  */
  37
  38 /**
  39  * crypto_alloc_rng() -- allocate RNG handle
  40  * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
  41  *            message digest cipher
  42  * @type: specifies the type of the cipher
  43  * @mask: specifies the mask for the cipher
  44  *
  45  * Allocate a cipher handle for a random number generator. The returned struct
  46  * crypto_rng is the cipher handle that is required for any subsequent
  47  * API invocation for that random number generator.
  48  *
  49  * For all random number generators, this call creates a new private copy of
  50  * the random number generator that does not share a state with other
  51  * instances. The only exception is the "krng" random number generator which
  52  * is a kernel crypto API use case for the get_random_bytes() function of the
  53  * /dev/random driver.
  54  *
  55  * Return: allocated cipher handle in case of success; IS_ERR() is true in case
  56  *         of an error, PTR_ERR() returns the error code.
  57  */
  58 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask);
  59
  60 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
  61 {
  62         return &tfm->base;
  63 }
  64
  65 /**
  66  * crypto_rng_alg - obtain name of RNG
  67  * @tfm: cipher handle
  68  *
  69  * Return the generic name (cra_name) of the initialized random number generator
  70  *
  71  * Return: generic name string
  72  */
  73 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
  74 {
  75         return &crypto_rng_tfm(tfm)->__crt_alg->cra_rng;
  76 }
  77
  78 /**
  79  * crypto_free_rng() - zeroize and free RNG handle
  80  * @tfm: cipher handle to be freed
  81  */
  82 static inline void crypto_free_rng(struct crypto_rng *tfm)
  83 {
  84         crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
  85 }
  86
  87 /**
  88  * crypto_rng_generate() - get random number
  89  * @tfm: cipher handle
  90  * @src: Input buffer holding additional data, may be NULL
  91  * @slen: Length of additional data
  92  * @dst: output buffer holding the random numbers
  93  * @dlen: length of the output buffer
  94  *
  95  * This function fills the caller-allocated buffer with random
  96  * numbers using the random number generator referenced by the
  97  * cipher handle.
  98  *
  99  * Return: 0 function was successful; < 0 if an error occurred
 100  */
 101 static inline int crypto_rng_generate(struct crypto_rng *tfm,
 102                                       const u8 *src, unsigned int slen,
 103                                       u8 *dst, unsigned int dlen)
 104 {
 105         return tfm->generate(tfm, src, slen, dst, dlen);
 106 }
 107
 108 /**
 109  * crypto_rng_get_bytes() - get random number
 110  * @tfm: cipher handle
 111  * @rdata: output buffer holding the random numbers
 112  * @dlen: length of the output buffer
 113  *
 114  * This function fills the caller-allocated buffer with random numbers using the
 115  * random number generator referenced by the cipher handle.
 116  *
 117  * Return: 0 function was successful; < 0 if an error occurred
 118  */
 119 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
 120                                        u8 *rdata, unsigned int dlen)
 121 {
 122         return crypto_rng_generate(tfm, NULL, 0, rdata, dlen);
 123 }
 124
 125 /**
 126  * crypto_rng_reset() - re-initialize the RNG
 127  * @tfm: cipher handle
 128  * @seed: seed input data
 129  * @slen: length of the seed input data
 130  *
 131  * The reset function completely re-initializes the random number generator
 132  * referenced by the cipher handle by clearing the current state. The new state
 133  * is initialized with the caller provided seed or automatically, depending
 134  * on the random number generator type (the ANSI X9.31 RNG requires
 135  * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding).
 136  * The seed is provided as a parameter to this function call. The provided seed
 137  * should have the length of the seed size defined for the random number
 138  * generator as defined by crypto_rng_seedsize.
 139  *
 140  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
 141  */
 142 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
 143                      unsigned int slen);
 144
 145 /**
 146  * crypto_rng_seedsize() - obtain seed size of RNG
 147  * @tfm: cipher handle
 148  *
 149  * The function returns the seed size for the random number generator
 150  * referenced by the cipher handle. This value may be zero if the random
 151  * number generator does not implement or require a reseeding. For example,
 152  * the SP800-90A DRBGs implement an automated reseeding after reaching a
 153  * pre-defined threshold.
 154  *
 155  * Return: seed size for the random number generator
 156  */
 157 static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
 158 {
 159         return crypto_rng_alg(tfm)->seedsize;
 160 }
 161
 162 #endif