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, 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 static inline int crypto_rng_reset(struct crypto_rng *tfm, 143 u8 *seed, unsigned int slen) 144 { 145 return tfm->seed(tfm, seed, slen); 146 } 147 148 /** 149 * crypto_rng_seedsize() - obtain seed size of RNG 150 * @tfm: cipher handle 151 * 152 * The function returns the seed size for the random number generator 153 * referenced by the cipher handle. This value may be zero if the random 154 * number generator does not implement or require a reseeding. For example, 155 * the SP800-90A DRBGs implement an automated reseeding after reaching a 156 * pre-defined threshold. 157 * 158 * Return: seed size for the random number generator 159 */ 160 static inline int crypto_rng_seedsize(struct crypto_rng *tfm) 161 { 162 return crypto_rng_alg(tfm)->seedsize; 163 } 164 165 #endif 166