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