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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Diffie-Hellman secret to be used with kpp API along with helper functions
*
* Copyright (c) 2016, Intel Corporation
* Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
*/
#ifndef _CRYPTO_DH_
#define _CRYPTO_DH_
/**
* DOC: DH Helper Functions
*
* To use DH with the KPP cipher API, the following data structure and
* functions should be used.
*
* To use DH with KPP, the following functions should be used to operate on
* a DH private key. The packet private key that can be set with
* the KPP API function call of crypto_kpp_set_secret.
*/
/**
* struct dh - define a DH private key
*
* @key: Private DH key
* @p: Diffie-Hellman parameter P
* @g: Diffie-Hellman generator G
* @key_size: Size of the private DH key
* @p_size: Size of DH parameter P
* @g_size: Size of DH generator G
*/
struct dh {
const void *key;
const void *p;
const void *g;
unsigned int key_size;
unsigned int p_size;
unsigned int g_size;
};
/**
* crypto_dh_key_len() - Obtain the size of the private DH key
* @params: private DH key
*
* This function returns the packet DH key size. A caller can use that
* with the provided DH private key reference to obtain the required
* memory size to hold a packet key.
*
* Return: size of the key in bytes
*/
unsigned int crypto_dh_key_len(const struct dh *params);
/**
* crypto_dh_encode_key() - encode the private key
* @buf: Buffer allocated by the caller to hold the packet DH
* private key. The buffer should be at least crypto_dh_key_len
* bytes in size.
* @len: Length of the packet private key buffer
* @params: Buffer with the caller-specified private key
*
* The DH implementations operate on a packet representation of the private
* key.
*
* Return: -EINVAL if buffer has insufficient size, 0 on success
*/
int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params);
/**
* crypto_dh_decode_key() - decode a private key
* @buf: Buffer holding a packet key that should be decoded
* @len: Length of the packet private key buffer
* @params: Buffer allocated by the caller that is filled with the
* unpacked DH private key.
*
* The unpacking obtains the private key by pointing @p to the correct location
* in @buf. Thus, both pointers refer to the same memory.
*
* Return: -EINVAL if buffer has insufficient size, 0 on success
*/
int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params);
/**
* __crypto_dh_decode_key() - decode a private key without parameter checks
* @buf: Buffer holding a packet key that should be decoded
* @len: Length of the packet private key buffer
* @params: Buffer allocated by the caller that is filled with the
* unpacked DH private key.
*
* Internal function providing the same services as the exported
* crypto_dh_decode_key(), but without any of those basic parameter
* checks conducted by the latter.
*
* Return: -EINVAL if buffer has insufficient size, 0 on success
*/
int __crypto_dh_decode_key(const char *buf, unsigned int len,
struct dh *params);
#endif
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