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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
29#include <crypto/ecc_curve.h>
30#include <linux/unaligned.h>
31
32/* One digit is u64 qword. */
33#define ECC_CURVE_NIST_P192_DIGITS 3
34#define ECC_CURVE_NIST_P256_DIGITS 4
35#define ECC_CURVE_NIST_P384_DIGITS 6
36#define ECC_CURVE_NIST_P521_DIGITS 9
37#define ECC_MAX_DIGITS DIV_ROUND_UP(521, 64) /* NIST P521 */
38
39#define ECC_DIGITS_TO_BYTES_SHIFT 3
40
41#define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
42
43#define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
44
45/*
46 * The integers r and s making up the signature are expected to be
47 * formatted as two consecutive u64 arrays of size ECC_MAX_BYTES.
48 * The bytes within each u64 digit are in native endianness,
49 * but the order of the u64 digits themselves is little endian.
50 * This format allows direct use by internal vli_*() functions.
51 */
52struct ecdsa_raw_sig {
53 u64 r[ECC_MAX_DIGITS];
54 u64 s[ECC_MAX_DIGITS];
55};
56
57/**
58 * ecc_swap_digits() - Copy ndigits from big endian array to native array
59 * @in: Input array
60 * @out: Output array
61 * @ndigits: Number of digits to copy
62 */
63static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigits)
64{
65 const __be64 *src = (__force __be64 *)in;
66 int i;
67
68 for (i = 0; i < ndigits; i++)
69 out[i] = get_unaligned_be64(&src[ndigits - 1 - i]);
70}
71
72/**
73 * ecc_digits_from_bytes() - Create ndigits-sized digits array from byte array
74 * @in: Input byte array
75 * @nbytes: Size of input byte array
76 * @out: Output digits array
77 * @ndigits: Number of digits to create from byte array
78 *
79 * The first byte in the input byte array is expected to hold the most
80 * significant bits of the large integer.
81 */
82void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes,
83 u64 *out, unsigned int ndigits);
84
85/**
86 * ecc_is_key_valid() - Validate a given ECDH private key
87 *
88 * @curve_id: id representing the curve to use
89 * @ndigits: curve's number of digits
90 * @private_key: private key to be used for the given curve
91 * @private_key_len: private key length
92 *
93 * Returns: 0 if the key is acceptable, a negative value otherwise
94 */
95int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
96 const u64 *private_key, unsigned int private_key_len);
97
98/**
99 * ecc_gen_privkey() - Generates an ECC private key.
100 * The private key is a random integer in the range 0 < random < n, where n is a
101 * prime that is the order of the cyclic subgroup generated by the distinguished
102 * point G.
103 * @curve_id: id representing the curve to use
104 * @ndigits: curve number of digits
105 * @private_key: buffer for storing the generated private key
106 *
107 * Returns: 0 if the private key was generated successfully, a negative value
108 * if an error occurred.
109 */
110int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits,
111 u64 *private_key);
112
113/**
114 * ecc_make_pub_key() - Compute an ECC public key
115 *
116 * @curve_id: id representing the curve to use
117 * @ndigits: curve's number of digits
118 * @private_key: pregenerated private key for the given curve
119 * @public_key: buffer for storing the generated public key
120 *
121 * Returns: 0 if the public key was generated successfully, a negative value
122 * if an error occurred.
123 */
124int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
125 const u64 *private_key, u64 *public_key);
126
127/**
128 * crypto_ecdh_shared_secret() - Compute a shared secret
129 *
130 * @curve_id: id representing the curve to use
131 * @ndigits: curve's number of digits
132 * @private_key: private key of part A
133 * @public_key: public key of counterpart B
134 * @secret: buffer for storing the calculated shared secret
135 *
136 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
137 * before using it for symmetric encryption or HMAC.
138 *
139 * Returns: 0 if the shared secret was generated successfully, a negative value
140 * if an error occurred.
141 */
142int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
143 const u64 *private_key, const u64 *public_key,
144 u64 *secret);
145
146/**
147 * ecc_is_pubkey_valid_partial() - Partial public key validation
148 *
149 * @curve: elliptic curve domain parameters
150 * @pk: public key as a point
151 *
152 * Validate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
153 * Public-Key Validation Routine.
154 *
155 * Note: There is no check that the public key is in the correct elliptic curve
156 * subgroup.
157 *
158 * Return: 0 if validation is successful, -EINVAL if validation is failed.
159 */
160int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
161 struct ecc_point *pk);
162
163/**
164 * ecc_is_pubkey_valid_full() - Full public key validation
165 *
166 * @curve: elliptic curve domain parameters
167 * @pk: public key as a point
168 *
169 * Validate public key according to SP800-56A section 5.6.2.3.3 ECC Full
170 * Public-Key Validation Routine.
171 *
172 * Return: 0 if validation is successful, -EINVAL if validation is failed.
173 */
174int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
175 struct ecc_point *pk);
176
177/**
178 * vli_is_zero() - Determine is vli is zero
179 *
180 * @vli: vli to check.
181 * @ndigits: length of the @vli
182 *
183 * Returns: %true if vli == 0, %false otherwise.
184 */
185bool vli_is_zero(const u64 *vli, unsigned int ndigits);
186
187/**
188 * vli_cmp() - compare left and right vlis
189 *
190 * @left: vli
191 * @right: vli
192 * @ndigits: length of both vlis
193 *
194 * Returns: sign of @left - @right, i.e. -1 if @left < @right,
195 * 0 if @left == @right, 1 if @left > @right.
196 */
197int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits);
198
199/**
200 * vli_sub() - Subtracts right from left
201 *
202 * @result: where to write result
203 * @left: vli
204 * @right: vli
205 * @ndigits: length of all vlis
206 *
207 * Note: can modify in-place.
208 *
209 * Return: carry bit.
210 */
211u64 vli_sub(u64 *result, const u64 *left, const u64 *right,
212 unsigned int ndigits);
213
214/**
215 * vli_from_be64() - Load vli from big-endian u64 array
216 *
217 * @dest: destination vli
218 * @src: source array of u64 BE values
219 * @ndigits: length of both vli and array
220 */
221void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits);
222
223/**
224 * vli_from_le64() - Load vli from little-endian u64 array
225 *
226 * @dest: destination vli
227 * @src: source array of u64 LE values
228 * @ndigits: length of both vli and array
229 */
230void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits);
231
232/**
233 * vli_mod_inv() - Modular inversion
234 *
235 * @result: where to write vli number
236 * @input: vli value to operate on
237 * @mod: modulus
238 * @ndigits: length of all vlis
239 */
240void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod,
241 unsigned int ndigits);
242
243/**
244 * vli_mod_mult_slow() - Modular multiplication
245 *
246 * @result: where to write result value
247 * @left: vli number to multiply with @right
248 * @right: vli number to multiply with @left
249 * @mod: modulus
250 * @ndigits: length of all vlis
251 *
252 * Note: Assumes that mod is big enough curve order.
253 */
254void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right,
255 const u64 *mod, unsigned int ndigits);
256
257/**
258 * vli_num_bits() - Counts the number of bits required for vli.
259 *
260 * @vli: vli to check.
261 * @ndigits: Length of the @vli
262 *
263 * Return: The number of bits required to represent @vli.
264 */
265unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits);
266
267/**
268 * ecc_alloc_point() - Allocate ECC point.
269 *
270 * @ndigits: Length of vlis in u64 qwords.
271 *
272 * Return: Pointer to the allocated point or NULL if allocation failed.
273 */
274struct ecc_point *ecc_alloc_point(unsigned int ndigits);
275
276/**
277 * ecc_free_point() - Free ECC point.
278 *
279 * @p: The point to free.
280 */
281void ecc_free_point(struct ecc_point *p);
282
283/**
284 * ecc_point_is_zero() - Check if point is zero.
285 *
286 * @point: Point to check for zero.
287 *
288 * Return: true if point is the point at infinity, false otherwise.
289 */
290bool ecc_point_is_zero(const struct ecc_point *point);
291
292/**
293 * ecc_point_mult_shamir() - Add two points multiplied by scalars
294 *
295 * @result: resulting point
296 * @x: scalar to multiply with @p
297 * @p: point to multiply with @x
298 * @y: scalar to multiply with @q
299 * @q: point to multiply with @y
300 * @curve: curve
301 *
302 * Returns result = x * p + x * q over the curve.
303 * This works faster than two multiplications and addition.
304 */
305void ecc_point_mult_shamir(const struct ecc_point *result,
306 const u64 *x, const struct ecc_point *p,
307 const u64 *y, const struct ecc_point *q,
308 const struct ecc_curve *curve);
309
310extern struct crypto_template ecdsa_x962_tmpl;
311extern struct crypto_template ecdsa_p1363_tmpl;
312#endif