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 <asm/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_MAX_DIGITS (512 / 64) /* due to ecrdsa */
37
38 #define ECC_DIGITS_TO_BYTES_SHIFT 3
39
40 #define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
41
42 #define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
43
44 /**
45 * ecc_swap_digits() - Copy ndigits from big endian array to native array
46 * @in: Input array
47 * @out: Output array
48 * @ndigits: Number of digits to copy
49 */
ecc_swap_digits(const void * in,u64 * out,unsigned int ndigits)50 static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigits)
51 {
52 const __be64 *src = (__force __be64 *)in;
53 int i;
54
55 for (i = 0; i < ndigits; i++)
56 out[i] = get_unaligned_be64(&src[ndigits - 1 - i]);
57 }
58
59 /**
60 * ecc_digits_from_bytes() - Create ndigits-sized digits array from byte array
61 * @in: Input byte array
62 * @nbytes Size of input byte array
63 * @out Output digits array
64 * @ndigits: Number of digits to create from byte array
65 */
66 void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes,
67 u64 *out, unsigned int ndigits);
68
69 /**
70 * ecc_is_key_valid() - Validate a given ECDH private key
71 *
72 * @curve_id: id representing the curve to use
73 * @ndigits: curve's number of digits
74 * @private_key: private key to be used for the given curve
75 * @private_key_len: private key length
76 *
77 * Returns 0 if the key is acceptable, a negative value otherwise
78 */
79 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
80 const u64 *private_key, unsigned int private_key_len);
81
82 /**
83 * ecc_gen_privkey() - Generates an ECC private key.
84 * The private key is a random integer in the range 0 < random < n, where n is a
85 * prime that is the order of the cyclic subgroup generated by the distinguished
86 * point G.
87 * @curve_id: id representing the curve to use
88 * @ndigits: curve number of digits
89 * @private_key: buffer for storing the generated private key
90 *
91 * Returns 0 if the private key was generated successfully, a negative value
92 * if an error occurred.
93 */
94 int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
95
96 /**
97 * ecc_make_pub_key() - Compute an ECC public key
98 *
99 * @curve_id: id representing the curve to use
100 * @ndigits: curve's number of digits
101 * @private_key: pregenerated private key for the given curve
102 * @public_key: buffer for storing the generated public key
103 *
104 * Returns 0 if the public key was generated successfully, a negative value
105 * if an error occurred.
106 */
107 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
108 const u64 *private_key, u64 *public_key);
109
110 /**
111 * crypto_ecdh_shared_secret() - Compute a shared secret
112 *
113 * @curve_id: id representing the curve to use
114 * @ndigits: curve's number of digits
115 * @private_key: private key of part A
116 * @public_key: public key of counterpart B
117 * @secret: buffer for storing the calculated shared secret
118 *
119 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
120 * before using it for symmetric encryption or HMAC.
121 *
122 * Returns 0 if the shared secret was generated successfully, a negative value
123 * if an error occurred.
124 */
125 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
126 const u64 *private_key, const u64 *public_key,
127 u64 *secret);
128
129 /**
130 * ecc_is_pubkey_valid_partial() - Partial public key validation
131 *
132 * @curve: elliptic curve domain parameters
133 * @pk: public key as a point
134 *
135 * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
136 * Public-Key Validation Routine.
137 *
138 * Note: There is no check that the public key is in the correct elliptic curve
139 * subgroup.
140 *
141 * Return: 0 if validation is successful, -EINVAL if validation is failed.
142 */
143 int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
144 struct ecc_point *pk);
145
146 /**
147 * ecc_is_pubkey_valid_full() - Full public key validation
148 *
149 * @curve: elliptic curve domain parameters
150 * @pk: public key as a point
151 *
152 * Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full
153 * Public-Key Validation Routine.
154 *
155 * Return: 0 if validation is successful, -EINVAL if validation is failed.
156 */
157 int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
158 struct ecc_point *pk);
159
160 /**
161 * vli_is_zero() - Determine is vli is zero
162 *
163 * @vli: vli to check.
164 * @ndigits: length of the @vli
165 */
166 bool vli_is_zero(const u64 *vli, unsigned int ndigits);
167
168 /**
169 * vli_cmp() - compare left and right vlis
170 *
171 * @left: vli
172 * @right: vli
173 * @ndigits: length of both vlis
174 *
175 * Returns sign of @left - @right, i.e. -1 if @left < @right,
176 * 0 if @left == @right, 1 if @left > @right.
177 */
178 int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits);
179
180 /**
181 * vli_sub() - Subtracts right from left
182 *
183 * @result: where to write result
184 * @left: vli
185 * @right vli
186 * @ndigits: length of all vlis
187 *
188 * Note: can modify in-place.
189 *
190 * Return: carry bit.
191 */
192 u64 vli_sub(u64 *result, const u64 *left, const u64 *right,
193 unsigned int ndigits);
194
195 /**
196 * vli_from_be64() - Load vli from big-endian u64 array
197 *
198 * @dest: destination vli
199 * @src: source array of u64 BE values
200 * @ndigits: length of both vli and array
201 */
202 void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits);
203
204 /**
205 * vli_from_le64() - Load vli from little-endian u64 array
206 *
207 * @dest: destination vli
208 * @src: source array of u64 LE values
209 * @ndigits: length of both vli and array
210 */
211 void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits);
212
213 /**
214 * vli_mod_inv() - Modular inversion
215 *
216 * @result: where to write vli number
217 * @input: vli value to operate on
218 * @mod: modulus
219 * @ndigits: length of all vlis
220 */
221 void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod,
222 unsigned int ndigits);
223
224 /**
225 * vli_mod_mult_slow() - Modular multiplication
226 *
227 * @result: where to write result value
228 * @left: vli number to multiply with @right
229 * @right: vli number to multiply with @left
230 * @mod: modulus
231 * @ndigits: length of all vlis
232 *
233 * Note: Assumes that mod is big enough curve order.
234 */
235 void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right,
236 const u64 *mod, unsigned int ndigits);
237
238 /**
239 * vli_num_bits() - Counts the number of bits required for vli.
240 *
241 * @vli: vli to check.
242 * @ndigits: Length of the @vli
243 *
244 * Return: The number of bits required to represent @vli.
245 */
246 unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits);
247
248 /**
249 * ecc_aloc_point() - Allocate ECC point.
250 *
251 * @ndigits: Length of vlis in u64 qwords.
252 *
253 * Return: Pointer to the allocated point or NULL if allocation failed.
254 */
255 struct ecc_point *ecc_alloc_point(unsigned int ndigits);
256
257 /**
258 * ecc_free_point() - Free ECC point.
259 *
260 * @p: The point to free.
261 */
262 void ecc_free_point(struct ecc_point *p);
263
264 /**
265 * ecc_point_is_zero() - Check if point is zero.
266 *
267 * @p: Point to check for zero.
268 *
269 * Return: true if point is the point at infinity, false otherwise.
270 */
271 bool ecc_point_is_zero(const struct ecc_point *point);
272
273 /**
274 * ecc_point_mult_shamir() - Add two points multiplied by scalars
275 *
276 * @result: resulting point
277 * @x: scalar to multiply with @p
278 * @p: point to multiply with @x
279 * @y: scalar to multiply with @q
280 * @q: point to multiply with @y
281 * @curve: curve
282 *
283 * Returns result = x * p + x * q over the curve.
284 * This works faster than two multiplications and addition.
285 */
286 void ecc_point_mult_shamir(const struct ecc_point *result,
287 const u64 *x, const struct ecc_point *p,
288 const u64 *y, const struct ecc_point *q,
289 const struct ecc_curve *curve);
290
291 #endif
292