156 lines
4.8 KiB
C
156 lines
4.8 KiB
C
/*
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* RNG: Random Number Generator algorithms under the crypto API
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*
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* Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#ifndef _CRYPTO_RNG_H
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#define _CRYPTO_RNG_H
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#include <linux/crypto.h>
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extern struct crypto_rng *crypto_default_rng;
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int crypto_get_default_rng(void);
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void crypto_put_default_rng(void);
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/**
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* DOC: Random number generator API
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*
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* The random number generator API is used with the ciphers of type
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* CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)
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*/
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static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm)
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{
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return (struct crypto_rng *)tfm;
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}
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/**
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* crypto_alloc_rng() -- allocate RNG handle
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* @alg_name: is the cra_name / name or cra_driver_name / driver name of the
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* message digest cipher
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* @type: specifies the type of the cipher
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* @mask: specifies the mask for the cipher
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*
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* Allocate a cipher handle for a random number generator. The returned struct
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* crypto_rng is the cipher handle that is required for any subsequent
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* API invocation for that random number generator.
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*
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* For all random number generators, this call creates a new private copy of
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* the random number generator that does not share a state with other
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* instances. The only exception is the "krng" random number generator which
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* is a kernel crypto API use case for the get_random_bytes() function of the
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* /dev/random driver.
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*
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* Return: allocated cipher handle in case of success; IS_ERR() is true in case
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* of an error, PTR_ERR() returns the error code.
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*/
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static inline struct crypto_rng *crypto_alloc_rng(const char *alg_name,
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u32 type, u32 mask)
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{
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type &= ~CRYPTO_ALG_TYPE_MASK;
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type |= CRYPTO_ALG_TYPE_RNG;
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mask |= CRYPTO_ALG_TYPE_MASK;
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return __crypto_rng_cast(crypto_alloc_base(alg_name, type, mask));
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}
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static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
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{
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return &tfm->base;
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}
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/**
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* crypto_rng_alg - obtain name of RNG
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* @tfm: cipher handle
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*
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* Return the generic name (cra_name) of the initialized random number generator
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*
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* Return: generic name string
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*/
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static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
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{
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return &crypto_rng_tfm(tfm)->__crt_alg->cra_rng;
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}
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static inline struct rng_tfm *crypto_rng_crt(struct crypto_rng *tfm)
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{
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return &crypto_rng_tfm(tfm)->crt_rng;
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}
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/**
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* crypto_free_rng() - zeroize and free RNG handle
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* @tfm: cipher handle to be freed
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*/
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static inline void crypto_free_rng(struct crypto_rng *tfm)
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{
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crypto_free_tfm(crypto_rng_tfm(tfm));
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}
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/**
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* crypto_rng_get_bytes() - get random number
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* @tfm: cipher handle
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* @rdata: output buffer holding the random numbers
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* @dlen: length of the output buffer
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*
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* This function fills the caller-allocated buffer with random numbers using the
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* random number generator referenced by the cipher handle.
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*
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* Return: > 0 function was successful and returns the number of generated
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* bytes; < 0 if an error occurred
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*/
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static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
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u8 *rdata, unsigned int dlen)
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{
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return crypto_rng_crt(tfm)->rng_gen_random(tfm, rdata, dlen);
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}
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/**
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* crypto_rng_reset() - re-initialize the RNG
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* @tfm: cipher handle
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* @seed: seed input data
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* @slen: length of the seed input data
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*
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* The reset function completely re-initializes the random number generator
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* referenced by the cipher handle by clearing the current state. The new state
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* is initialized with the caller provided seed or automatically, depending
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* on the random number generator type (the ANSI X9.31 RNG requires
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* caller-provided seed, the SP800-90A DRBGs perform an automatic seeding).
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* The seed is provided as a parameter to this function call. The provided seed
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* should have the length of the seed size defined for the random number
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* generator as defined by crypto_rng_seedsize.
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*
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* Return: 0 if the setting of the key was successful; < 0 if an error occurred
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*/
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static inline int crypto_rng_reset(struct crypto_rng *tfm,
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u8 *seed, unsigned int slen)
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{
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return crypto_rng_crt(tfm)->rng_reset(tfm, seed, slen);
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}
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/**
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* crypto_rng_seedsize() - obtain seed size of RNG
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* @tfm: cipher handle
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*
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* The function returns the seed size for the random number generator
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* referenced by the cipher handle. This value may be zero if the random
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* number generator does not implement or require a reseeding. For example,
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* the SP800-90A DRBGs implement an automated reseeding after reaching a
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* pre-defined threshold.
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*
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* Return: seed size for the random number generator
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*/
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static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
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{
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return crypto_rng_alg(tfm)->seedsize;
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}
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#endif
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