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/*
* ECDH params to be used with kpp API
*
* Copyright (c) 2016, Intel Corporation
* Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#ifndef _CRYPTO_ECDH_
#define _CRYPTO_ECDH_
/**
* DOC: ECDH Helper Functions
*
* To use ECDH with the KPP cipher API, the following data structure and
* functions should be used.
*
* The ECC curves known to the ECDH implementation are specified in this
* header file.
*
* To use ECDH with KPP, the following functions should be used to operate on
* an ECDH private key. The packet private key that can be set with
* the KPP API function call of crypto_kpp_set_secret.
*/
/* Curves IDs */
#define ECC_CURVE_NIST_P192 0x0001
#define ECC_CURVE_NIST_P256 0x0002
/**
* struct ecdh - define an ECDH private key
*
* @curve_id: ECC curve the key is based on.
* @key: Private ECDH key
* @key_size: Size of the private ECDH key
*/
struct ecdh {
unsigned short curve_id;
char *key;
unsigned short key_size;
};
/**
* crypto_ecdh_key_len() - Obtain the size of the private ECDH key
* @params: private ECDH key
*
* This function returns the packet ECDH key size. A caller can use that
* with the provided ECDH private key reference to obtain the required
* memory size to hold a packet key.
*
* Return: size of the key in bytes
*/
int crypto_ecdh_key_len(const struct ecdh *params);
/**
* crypto_ecdh_encode_key() - encode the private key
* @buf: Buffer allocated by the caller to hold the packet ECDH
* private key. The buffer should be at least crypto_ecdh_key_len
* bytes in size.
* @len: Length of the packet private key buffer
* @p: Buffer with the caller-specified private key
*
* The ECDH implementations operate on a packet representation of the private
* key.
*
* Return: -EINVAL if buffer has insufficient size, 0 on success
*/
int crypto_ecdh_encode_key(char *buf, unsigned int len, const struct ecdh *p);
/**
* crypto_ecdh_decode_key() - decode a private key
* @buf: Buffer holding a packet key that should be decoded
* @len: Length of the packet private key buffer
* @p: Buffer allocated by the caller that is filled with the
* unpacked ECDH 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_ecdh_decode_key(const char *buf, unsigned int len, struct ecdh *p);
#endif
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