[linux.git] / crypto / ecc.h

/*
 * 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

/* One digit is u64 qword. */
#define ECC_CURVE_NIST_P192_DIGITS  3
#define ECC_CURVE_NIST_P256_DIGITS  4
#define ECC_MAX_DIGITS             (512 / 64)

#define ECC_DIGITS_TO_BYTES_SHIFT 3

/**
 * struct ecc_point - elliptic curve point in affine coordinates
 *
 * @x:		X coordinate in vli form.
 * @y:		Y coordinate in vli form.
 * @ndigits:	Length of vlis in u64 qwords.
 */
struct ecc_point {
	u64 *x;
	u64 *y;
	u8 ndigits;
};

#define ECC_POINT_INIT(x, y, ndigits)	(struct ecc_point) { x, y, ndigits }

/**
 * struct ecc_curve - definition of elliptic curve
 *
 * @name:	Short name of the curve.
 * @g:		Generator point of the curve.
 * @p:		Prime number, if Barrett's reduction is used for this curve
 *		pre-calculated value 'mu' is appended to the @p after ndigits.
 *		Use of Barrett's reduction is heuristically determined in
 *		vli_mmod_fast().
 * @n:		Order of the curve group.
 * @a:		Curve parameter a.
 * @b:		Curve parameter b.
 */
struct ecc_curve {
	char *name;
	struct ecc_point g;
	u64 *p;
	u64 *n;
	u64 *a;
	u64 *b;
};

/**
 * 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 *privkey);

/**
 * 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);

/**
 * 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
Commit	Line	Data
3c4b2390 SB	1	/*
	2	* Copyright (c) 2013, Kenneth MacKay
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions are
	7	* met:
	8	* * Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* * Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	*
	14	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	15	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	16	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	17	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	18	* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	19	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	20	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	21	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	22	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	23	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	24	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	25	*/
	26	#ifndef _CRYPTO_ECC_H
	27	#define _CRYPTO_ECC_H
	28
0d7a7864	29	/* One digit is u64 qword. */
d5c3b178 KC	30	#define ECC_CURVE_NIST_P192_DIGITS 3
d5c3b178 KC	31	#define ECC_CURVE_NIST_P256_DIGITS 4
0d7a7864	32	#define ECC_MAX_DIGITS (512 / 64)
3c4b2390 SB	33
	34	#define ECC_DIGITS_TO_BYTES_SHIFT 3
	35
4a2289da VC	36	/**
	37	* struct ecc_point - elliptic curve point in affine coordinates
	38	*
	39	* @x: X coordinate in vli form.
	40	* @y: Y coordinate in vli form.
	41	* @ndigits: Length of vlis in u64 qwords.
	42	*/
	43	struct ecc_point {
	44	u64 *x;
	45	u64 *y;
	46	u8 ndigits;
	47	};
	48
0d7a7864 VC	49	#define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
0d7a7864 VC	50
4a2289da VC	51	/**
	52	* struct ecc_curve - definition of elliptic curve
	53	*
	54	* @name: Short name of the curve.
	55	* @g: Generator point of the curve.
	56	* @p: Prime number, if Barrett's reduction is used for this curve
	57	* pre-calculated value 'mu' is appended to the @p after ndigits.
	58	* Use of Barrett's reduction is heuristically determined in
	59	* vli_mmod_fast().
	60	* @n: Order of the curve group.
	61	* @a: Curve parameter a.
	62	* @b: Curve parameter b.
	63	*/
	64	struct ecc_curve {
	65	char *name;
	66	struct ecc_point g;
	67	u64 *p;
	68	u64 *n;
	69	u64 *a;
	70	u64 *b;
	71	};
	72
3c4b2390 SB	73	/**
	74	* ecc_is_key_valid() - Validate a given ECDH private key
	75	*
	76	* @curve_id: id representing the curve to use
c0ca1215	77	* @ndigits: curve's number of digits
3c4b2390	78	* @private_key: private key to be used for the given curve
c0ca1215	79	* @private_key_len: private key length
3c4b2390 SB	80	*
	81	* Returns 0 if the key is acceptable, a negative value otherwise
	82	*/
	83	int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
ad269597	84	const u64 *private_key, unsigned int private_key_len);
3c4b2390	85
6755fd26 TA	86	/**
	87	* ecc_gen_privkey() - Generates an ECC private key.
	88	* The private key is a random integer in the range 0 < random < n, where n is a
	89	* prime that is the order of the cyclic subgroup generated by the distinguished
	90	* point G.
	91	* @curve_id: id representing the curve to use
	92	* @ndigits: curve number of digits
	93	* @private_key: buffer for storing the generated private key
	94	*
	95	* Returns 0 if the private key was generated successfully, a negative value
	96	* if an error occurred.
	97	*/
	98	int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
	99
3c4b2390	100	/**
7380c56d	101	* ecc_make_pub_key() - Compute an ECC public key
3c4b2390 SB	102	*
3c4b2390 SB	103	* @curve_id: id representing the curve to use
c0ca1215	104	* @ndigits: curve's number of digits
3c4b2390	105	* @private_key: pregenerated private key for the given curve
c0ca1215	106	* @public_key: buffer for storing the generated public key
3c4b2390 SB	107	*
	108	* Returns 0 if the public key was generated successfully, a negative value
	109	* if an error occurred.
	110	*/
7380c56d TA	111	int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
7380c56d TA	112	const u64 private_key, u64 public_key);
3c4b2390 SB	113
3c4b2390 SB	114	/**
8f44df15	115	* crypto_ecdh_shared_secret() - Compute a shared secret
3c4b2390 SB	116	*
3c4b2390 SB	117	* @curve_id: id representing the curve to use
c0ca1215	118	* @ndigits: curve's number of digits
3c4b2390	119	* @private_key: private key of part A
3c4b2390	120	* @public_key: public key of counterpart B
3c4b2390	121	* @secret: buffer for storing the calculated shared secret
3c4b2390	122	*
8f44df15	123	* Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
3c4b2390 SB	124	* before using it for symmetric encryption or HMAC.
	125	*
	126	* Returns 0 if the shared secret was generated successfully, a negative value
	127	* if an error occurred.
	128	*/
8f44df15	129	int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
ad269597 TA	130	const u64 private_key, const u64 public_key,
ad269597 TA	131	u64 *secret);
4a2289da VC	132
	133	/**
	134	* ecc_is_pubkey_valid_partial() - Partial public key validation
	135	*
	136	* @curve: elliptic curve domain parameters
	137	* @pk: public key as a point
	138	*
	139	* Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
	140	* Public-Key Validation Routine.
	141	*
	142	* Note: There is no check that the public key is in the correct elliptic curve
	143	* subgroup.
	144	*
	145	* Return: 0 if validation is successful, -EINVAL if validation is failed.
	146	*/
	147	int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
	148	struct ecc_point *pk);
	149
6914dd53 SM	150	/**
	151	* ecc_is_pubkey_valid_full() - Full public key validation
	152	*
	153	* @curve: elliptic curve domain parameters
	154	* @pk: public key as a point
	155	*
	156	* Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full
	157	* Public-Key Validation Routine.
	158	*
	159	* Return: 0 if validation is successful, -EINVAL if validation is failed.
	160	*/
	161	int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
	162	struct ecc_point *pk);
	163
4a2289da VC	164	/**
	165	* vli_is_zero() - Determine is vli is zero
	166	*
	167	* @vli: vli to check.
	168	* @ndigits: length of the @vli
	169	*/
	170	bool vli_is_zero(const u64 *vli, unsigned int ndigits);
	171
	172	/**
	173	* vli_cmp() - compare left and right vlis
	174	*
	175	* @left: vli
	176	* @right: vli
	177	* @ndigits: length of both vlis
	178	*
	179	* Returns sign of @left - @right, i.e. -1 if @left < @right,
	180	* 0 if @left == @right, 1 if @left > @right.
	181	*/
	182	int vli_cmp(const u64 left, const u64 right, unsigned int ndigits);
	183
	184	/**
	185	* vli_sub() - Subtracts right from left
	186	*
	187	* @result: where to write result
	188	* @left: vli
	189	* @right vli
	190	* @ndigits: length of all vlis
	191	*
	192	* Note: can modify in-place.
	193	*
	194	* Return: carry bit.
	195	*/
	196	u64 vli_sub(u64 result, const u64 left, const u64 *right,
	197	unsigned int ndigits);
	198
0d7a7864 VC	199	/**
	200	* vli_from_be64() - Load vli from big-endian u64 array
	201	*
	202	* @dest: destination vli
	203	* @src: source array of u64 BE values
	204	* @ndigits: length of both vli and array
	205	*/
	206	void vli_from_be64(u64 dest, const void src, unsigned int ndigits);
	207
	208	/**
	209	* vli_from_le64() - Load vli from little-endian u64 array
	210	*
	211	* @dest: destination vli
	212	* @src: source array of u64 LE values
	213	* @ndigits: length of both vli and array
	214	*/
	215	void vli_from_le64(u64 dest, const void src, unsigned int ndigits);
	216
4a2289da VC	217	/**
	218	* vli_mod_inv() - Modular inversion
	219	*
	220	* @result: where to write vli number
	221	* @input: vli value to operate on
	222	* @mod: modulus
	223	* @ndigits: length of all vlis
	224	*/
	225	void vli_mod_inv(u64 result, const u64 input, const u64 *mod,
	226	unsigned int ndigits);
	227
0d7a7864 VC	228	/**
	229	* vli_mod_mult_slow() - Modular multiplication
	230	*
	231	* @result: where to write result value
	232	* @left: vli number to multiply with @right
	233	* @right: vli number to multiply with @left
	234	* @mod: modulus
	235	* @ndigits: length of all vlis
	236	*
	237	* Note: Assumes that mod is big enough curve order.
	238	*/
	239	void vli_mod_mult_slow(u64 result, const u64 left, const u64 *right,
	240	const u64 *mod, unsigned int ndigits);
	241
	242	/**
	243	* ecc_point_mult_shamir() - Add two points multiplied by scalars
	244	*
	245	* @result: resulting point
	246	* @x: scalar to multiply with @p
	247	* @p: point to multiply with @x
	248	* @y: scalar to multiply with @q
	249	* @q: point to multiply with @y
	250	* @curve: curve
	251	*
	252	* Returns result = x * p + x * q over the curve.
	253	* This works faster than two multiplications and addition.
	254	*/
	255	void ecc_point_mult_shamir(const struct ecc_point *result,
	256	const u64 x, const struct ecc_point p,
	257	const u64 y, const struct ecc_point q,
	258	const struct ecc_curve *curve);
3c4b2390	259	#endif