/*
* Copyright (c) 2013, Kenneth MacKay
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _CRYPTO_ECC_H
#define _CRYPTO_ECC_H
#include <crypto/ecc_curve.h>
#include <linux/unaligned.h>
/* One digit is u64 qword. */
#define ECC_CURVE_NIST_P192_DIGITS 3
#define ECC_CURVE_NIST_P256_DIGITS 4
#define ECC_CURVE_NIST_P384_DIGITS 6
#define ECC_CURVE_NIST_P521_DIGITS 9
#define ECC_MAX_DIGITS DIV_ROUND_UP(521, 64) /* NIST P521 */
#define ECC_DIGITS_TO_BYTES_SHIFT 3
#define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
#define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
/**
* ecc_swap_digits() - Copy ndigits from big endian array to native array
* @in: Input array
* @out: Output array
* @ndigits: Number of digits to copy
*/
static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigits)
{
const __be64 *src = (__force __be64 *)in;
int i;
for (i = 0; i < ndigits; i++)
out[i] = get_unaligned_be64(&src[ndigits - 1 - i]);
}
/**
* ecc_digits_from_bytes() - Create ndigits-sized digits array from byte array
* @in: Input byte array
* @nbytes Size of input byte array
* @out Output digits array
* @ndigits: Number of digits to create from byte array
*
* The first byte in the input byte array is expected to hold the most
* significant bits of the large integer.
*/
void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes,
u64 *out, unsigned int ndigits);
/**
* ecc_is_key_valid() - Validate a given ECDH private key
*
* @curve_id: id representing the curve to use
* @ndigits: curve's number of digits
* @private_key: private key to be used for the given curve
* @private_key_len: private key length
*
* Returns 0 if the key is acceptable, a negative value otherwise
*/
int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
const u64 *private_key, unsigned int private_key_len);
/**
* ecc_gen_privkey() - Generates an ECC private key.
* The private key is a random integer in the range 0 < random < n, where n is a
* prime that is the order of the cyclic subgroup generated by the distinguished
* point G.
* @curve_id: id representing the curve to use
* @ndigits: curve number of digits
* @private_key: buffer for storing the generated private key
*
* Returns 0 if the private key was generated successfully, a negative value
* if an error occurred.
*/
int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits,
u64 *private_key);
/**
* ecc_make_pub_key() - Compute an ECC public key
*
* @curve_id: id representing the curve to use
* @ndigits: curve's number of digits
* @private_key: pregenerated private key for the given curve
* @public_key: buffer for storing the generated public key
*
* Returns 0 if the public key was generated successfully, a negative value
* if an error occurred.
*/
int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
const u64 *private_key, u64 *public_key);
/**
* crypto_ecdh_shared_secret() - Compute a shared secret
*
* @curve_id: id representing the curve to use
* @ndigits: curve's number of digits
* @private_key: private key of part A
* @public_key: public key of counterpart B
* @secret: buffer for storing the calculated shared secret
*
* Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
* before using it for symmetric encryption or HMAC.
*
* Returns 0 if the shared secret was generated successfully, a negative value
* if an error occurred.
*/
int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
const u64 *private_key, const u64 *public_key,
u64 *secret);
/**
* ecc_is_pubkey_valid_partial() - Partial public key validation
*
* @curve: elliptic curve domain parameters
* @pk: public key as a point
*
* Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
* Public-Key Validation Routine.
*
* Note: There is no check that the public key is in the correct elliptic curve
* subgroup.
*
* Return: 0 if validation is successful, -EINVAL if validation is failed.
*/
int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
struct ecc_point *pk);
/**
* ecc_is_pubkey_valid_full() - Full public key validation
*
* @curve: elliptic curve domain parameters
* @pk: public key as a point
*
* Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full
* Public-Key Validation Routine.
*
* Return: 0 if validation is successful, -EINVAL if validation is failed.
*/
int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
struct ecc_point *pk);
/**
* vli_is_zero() - Determine is vli is zero
*
* @vli: vli to check.
* @ndigits: length of the @vli
*/
bool vli_is_zero(const u64 *vli, unsigned int ndigits);
/**
* vli_cmp() - compare left and right vlis
*
* @left: vli
* @right: vli
* @ndigits: length of both vlis
*
* Returns sign of @left - @right, i.e. -1 if @left < @right,
* 0 if @left == @right, 1 if @left > @right.
*/
int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits);
/**
* vli_sub() - Subtracts right from left
*
* @result: where to write result
* @left: vli
* @right vli
* @ndigits: length of all vlis
*
* Note: can modify in-place.
*
* Return: carry bit.
*/
u64 vli_sub(u64 *result, const u64 *left, const u64 *right,
unsigned int ndigits);
/**
* vli_from_be64() - Load vli from big-endian u64 array
*
* @dest: destination vli
* @src: source array of u64 BE values
* @ndigits: length of both vli and array
*/
void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits);
/**
* vli_from_le64() - Load vli from little-endian u64 array
*
* @dest: destination vli
* @src: source array of u64 LE values
* @ndigits: length of both vli and array
*/
void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits);
/**
* vli_mod_inv() - Modular inversion
*
* @result: where to write vli number
* @input: vli value to operate on
* @mod: modulus
* @ndigits: length of all vlis
*/
void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod,
unsigned int ndigits);
/**
* vli_mod_mult_slow() - Modular multiplication
*
* @result: where to write result value
* @left: vli number to multiply with @right
* @right: vli number to multiply with @left
* @mod: modulus
* @ndigits: length of all vlis
*
* Note: Assumes that mod is big enough curve order.
*/
void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right,
const u64 *mod, unsigned int ndigits);
/**
* vli_num_bits() - Counts the number of bits required for vli.
*
* @vli: vli to check.
* @ndigits: Length of the @vli
*
* Return: The number of bits required to represent @vli.
*/
unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits);
/**
* ecc_aloc_point() - Allocate ECC point.
*
* @ndigits: Length of vlis in u64 qwords.
*
* Return: Pointer to the allocated point or NULL if allocation failed.
*/
struct ecc_point *ecc_alloc_point(unsigned int ndigits);
/**
* ecc_free_point() - Free ECC point.
*
* @p: The point to free.
*/
void ecc_free_point(struct ecc_point *p);
/**
* ecc_point_is_zero() - Check if point is zero.
*
* @p: Point to check for zero.
*
* Return: true if point is the point at infinity, false otherwise.
*/
bool ecc_point_is_zero(const struct ecc_point *point);
/**
* ecc_point_mult_shamir() - Add two points multiplied by scalars
*
* @result: resulting point
* @x: scalar to multiply with @p
* @p: point to multiply with @x
* @y: scalar to multiply with @q
* @q: point to multiply with @y
* @curve: curve
*
* Returns result = x * p + x * q over the curve.
* This works faster than two multiplications and addition.
*/
void ecc_point_mult_shamir(const struct ecc_point *result,
const u64 *x, const struct ecc_point *p,
const u64 *y, const struct ecc_point *q,
const struct ecc_curve *curve);
#endif
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