[linux-block.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_CURVE_NIST_P384_DIGITS  6
#define ECC_MAX_DIGITS              (512 / 64) /* due to ecrdsa */

#define ECC_DIGITS_TO_BYTES_SHIFT 3

#define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)

/**
 * 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_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 u64 *in, u64 *out, unsigned int ndigits)
{
	const __be64 *src = (__force __be64 *)in;
	int i;

	for (i = 0; i < ndigits; i++)
		out[i] = be64_to_cpu(src[ndigits - 1 - i]);
}

/**
 * ecc_get_curve()  - Get a curve given its curve_id
 * @curve_id:  Id of the curve
 *
 * Returns pointer to the curve data, NULL if curve is not available
 */
const struct ecc_curve *ecc_get_curve(unsigned int curve_id);

/**
 * 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
149ca161 SA	32	#define ECC_CURVE_NIST_P384_DIGITS 6
149ca161 SA	33	#define ECC_MAX_DIGITS (512 / 64) /* due to ecrdsa */
3c4b2390 SB	34
	35	#define ECC_DIGITS_TO_BYTES_SHIFT 3
	36
4e660291 SB	37	#define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
4e660291 SB	38
4a2289da VC	39	/**
	40	* struct ecc_point - elliptic curve point in affine coordinates
	41	*
	42	* @x: X coordinate in vli form.
	43	* @y: Y coordinate in vli form.
	44	* @ndigits: Length of vlis in u64 qwords.
	45	*/
	46	struct ecc_point {
	47	u64 *x;
	48	u64 *y;
	49	u8 ndigits;
	50	};
	51
0d7a7864 VC	52	#define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
0d7a7864 VC	53
4a2289da VC	54	/**
	55	* struct ecc_curve - definition of elliptic curve
	56	*
	57	* @name: Short name of the curve.
	58	* @g: Generator point of the curve.
	59	* @p: Prime number, if Barrett's reduction is used for this curve
	60	* pre-calculated value 'mu' is appended to the @p after ndigits.
	61	* Use of Barrett's reduction is heuristically determined in
	62	* vli_mmod_fast().
	63	* @n: Order of the curve group.
	64	* @a: Curve parameter a.
	65	* @b: Curve parameter b.
	66	*/
	67	struct ecc_curve {
	68	char *name;
	69	struct ecc_point g;
	70	u64 *p;
	71	u64 *n;
	72	u64 *a;
	73	u64 *b;
	74	};
	75
4e660291 SB	76	/**
	77	* ecc_swap_digits() - Copy ndigits from big endian array to native array
	78	* @in: Input array
	79	* @out: Output array
	80	* @ndigits: Number of digits to copy
	81	*/
	82	static inline void ecc_swap_digits(const u64 in, u64 out, unsigned int ndigits)
	83	{
	84	const __be64 src = (__force __be64 )in;
	85	int i;
	86
	87	for (i = 0; i < ndigits; i++)
	88	out[i] = be64_to_cpu(src[ndigits - 1 - i]);
	89	}
	90
	91	/**
	92	* ecc_get_curve() - Get a curve given its curve_id
	93	* @curve_id: Id of the curve
	94	*
	95	* Returns pointer to the curve data, NULL if curve is not available
	96	*/
	97	const struct ecc_curve *ecc_get_curve(unsigned int curve_id);
	98
3c4b2390 SB	99	/**
	100	* ecc_is_key_valid() - Validate a given ECDH private key
	101	*
	102	* @curve_id: id representing the curve to use
c0ca1215	103	* @ndigits: curve's number of digits
3c4b2390	104	* @private_key: private key to be used for the given curve
c0ca1215	105	* @private_key_len: private key length
3c4b2390 SB	106	*
	107	* Returns 0 if the key is acceptable, a negative value otherwise
	108	*/
	109	int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
ad269597	110	const u64 *private_key, unsigned int private_key_len);
3c4b2390	111
6755fd26 TDA	112	/**
	113	* ecc_gen_privkey() - Generates an ECC private key.
	114	* The private key is a random integer in the range 0 < random < n, where n is a
	115	* prime that is the order of the cyclic subgroup generated by the distinguished
	116	* point G.
	117	* @curve_id: id representing the curve to use
	118	* @ndigits: curve number of digits
	119	* @private_key: buffer for storing the generated private key
	120	*
	121	* Returns 0 if the private key was generated successfully, a negative value
	122	* if an error occurred.
	123	*/
	124	int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
	125
3c4b2390	126	/**
7380c56d	127	* ecc_make_pub_key() - Compute an ECC public key
3c4b2390 SB	128	*
3c4b2390 SB	129	* @curve_id: id representing the curve to use
c0ca1215	130	* @ndigits: curve's number of digits
3c4b2390	131	* @private_key: pregenerated private key for the given curve
c0ca1215	132	* @public_key: buffer for storing the generated public key
3c4b2390 SB	133	*
	134	* Returns 0 if the public key was generated successfully, a negative value
	135	* if an error occurred.
	136	*/
7380c56d TDA	137	int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
7380c56d TDA	138	const u64 private_key, u64 public_key);
3c4b2390 SB	139
3c4b2390 SB	140	/**
8f44df15	141	* crypto_ecdh_shared_secret() - Compute a shared secret
3c4b2390 SB	142	*
3c4b2390 SB	143	* @curve_id: id representing the curve to use
c0ca1215	144	* @ndigits: curve's number of digits
3c4b2390	145	* @private_key: private key of part A
3c4b2390	146	* @public_key: public key of counterpart B
3c4b2390	147	* @secret: buffer for storing the calculated shared secret
3c4b2390	148	*
8f44df15	149	* Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
3c4b2390 SB	150	* before using it for symmetric encryption or HMAC.
	151	*
	152	* Returns 0 if the shared secret was generated successfully, a negative value
	153	* if an error occurred.
	154	*/
8f44df15	155	int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
ad269597 TDA	156	const u64 private_key, const u64 public_key,
ad269597 TDA	157	u64 *secret);
4a2289da VC	158
	159	/**
	160	* ecc_is_pubkey_valid_partial() - Partial public key validation
	161	*
	162	* @curve: elliptic curve domain parameters
	163	* @pk: public key as a point
	164	*
	165	* Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
	166	* Public-Key Validation Routine.
	167	*
	168	* Note: There is no check that the public key is in the correct elliptic curve
	169	* subgroup.
	170	*
	171	* Return: 0 if validation is successful, -EINVAL if validation is failed.
	172	*/
	173	int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
	174	struct ecc_point *pk);
	175
6914dd53 SM	176	/**
	177	* ecc_is_pubkey_valid_full() - Full public key validation
	178	*
	179	* @curve: elliptic curve domain parameters
	180	* @pk: public key as a point
	181	*
	182	* Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full
	183	* Public-Key Validation Routine.
	184	*
	185	* Return: 0 if validation is successful, -EINVAL if validation is failed.
	186	*/
	187	int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
	188	struct ecc_point *pk);
	189
4a2289da VC	190	/**
	191	* vli_is_zero() - Determine is vli is zero
	192	*
	193	* @vli: vli to check.
	194	* @ndigits: length of the @vli
	195	*/
	196	bool vli_is_zero(const u64 *vli, unsigned int ndigits);
	197
	198	/**
	199	* vli_cmp() - compare left and right vlis
	200	*
	201	* @left: vli
	202	* @right: vli
	203	* @ndigits: length of both vlis
	204	*
	205	* Returns sign of @left - @right, i.e. -1 if @left < @right,
	206	* 0 if @left == @right, 1 if @left > @right.
	207	*/
	208	int vli_cmp(const u64 left, const u64 right, unsigned int ndigits);
	209
	210	/**
	211	* vli_sub() - Subtracts right from left
	212	*
	213	* @result: where to write result
	214	* @left: vli
	215	* @right vli
	216	* @ndigits: length of all vlis
	217	*
	218	* Note: can modify in-place.
	219	*
	220	* Return: carry bit.
	221	*/
	222	u64 vli_sub(u64 result, const u64 left, const u64 *right,
	223	unsigned int ndigits);
	224
0d7a7864 VC	225	/**
	226	* vli_from_be64() - Load vli from big-endian u64 array
	227	*
	228	* @dest: destination vli
	229	* @src: source array of u64 BE values
	230	* @ndigits: length of both vli and array
	231	*/
	232	void vli_from_be64(u64 dest, const void src, unsigned int ndigits);
	233
	234	/**
	235	* vli_from_le64() - Load vli from little-endian u64 array
	236	*
	237	* @dest: destination vli
	238	* @src: source array of u64 LE values
	239	* @ndigits: length of both vli and array
	240	*/
	241	void vli_from_le64(u64 dest, const void src, unsigned int ndigits);
	242
4a2289da VC	243	/**
	244	* vli_mod_inv() - Modular inversion
	245	*
	246	* @result: where to write vli number
	247	* @input: vli value to operate on
	248	* @mod: modulus
	249	* @ndigits: length of all vlis
	250	*/
	251	void vli_mod_inv(u64 result, const u64 input, const u64 *mod,
	252	unsigned int ndigits);
	253
0d7a7864 VC	254	/**
	255	* vli_mod_mult_slow() - Modular multiplication
	256	*
	257	* @result: where to write result value
	258	* @left: vli number to multiply with @right
	259	* @right: vli number to multiply with @left
	260	* @mod: modulus
	261	* @ndigits: length of all vlis
	262	*
	263	* Note: Assumes that mod is big enough curve order.
	264	*/
	265	void vli_mod_mult_slow(u64 result, const u64 left, const u64 *right,
	266	const u64 *mod, unsigned int ndigits);
	267
	268	/**
	269	* ecc_point_mult_shamir() - Add two points multiplied by scalars
	270	*
	271	* @result: resulting point
	272	* @x: scalar to multiply with @p
	273	* @p: point to multiply with @x
	274	* @y: scalar to multiply with @q
	275	* @q: point to multiply with @y
	276	* @curve: curve
	277	*
	278	* Returns result = x * p + x * q over the curve.
	279	* This works faster than two multiplications and addition.
	280	*/
	281	void ecc_point_mult_shamir(const struct ecc_point *result,
	282	const u64 x, const struct ecc_point p,
	283	const u64 y, const struct ecc_point q,
	284	const struct ecc_curve *curve);
3c4b2390	285	#endif