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
31 /* One digit is u64 qword. */
32 #define ECC_CURVE_NIST_P192_DIGITS 3
33 #define ECC_CURVE_NIST_P256_DIGITS 4
34 #define ECC_CURVE_NIST_P384_DIGITS 6
35 #define ECC_MAX_DIGITS (512 / 64) /* due to ecrdsa */
36
37 #define ECC_DIGITS_TO_BYTES_SHIFT 3
38
39 #define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
40
41 #define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
42
43 /**
44 * ecc_swap_digits() - Copy ndigits from big endian array to native array
45 * @in: Input array
46 * @out: Output array
47 * @ndigits: Number of digits to copy
48 */
ecc_swap_digits(const u64 * in,u64 * out,unsigned int ndigits)49 static inline void ecc_swap_digits(const u64 *in, u64 *out, unsigned int ndigits)
50 {
51 const __be64 *src = (__force __be64 *)in;
52 int i;
53
54 for (i = 0; i < ndigits; i++)
55 out[i] = be64_to_cpu(src[ndigits - 1 - i]);
56 }
57
58 /**
59 * ecc_is_key_valid() - Validate a given ECDH private key
60 *
61 * @curve_id: id representing the curve to use
62 * @ndigits: curve's number of digits
63 * @private_key: private key to be used for the given curve
64 * @private_key_len: private key length
65 *
66 * Returns 0 if the key is acceptable, a negative value otherwise
67 */
68 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
69 const u64 *private_key, unsigned int private_key_len);
70
71 /**
72 * ecc_gen_privkey() - Generates an ECC private key.
73 * The private key is a random integer in the range 0 < random < n, where n is a
74 * prime that is the order of the cyclic subgroup generated by the distinguished
75 * point G.
76 * @curve_id: id representing the curve to use
77 * @ndigits: curve number of digits
78 * @private_key: buffer for storing the generated private key
79 *
80 * Returns 0 if the private key was generated successfully, a negative value
81 * if an error occurred.
82 */
83 int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
84
85 /**
86 * ecc_make_pub_key() - Compute an ECC public key
87 *
88 * @curve_id: id representing the curve to use
89 * @ndigits: curve's number of digits
90 * @private_key: pregenerated private key for the given curve
91 * @public_key: buffer for storing the generated public key
92 *
93 * Returns 0 if the public key was generated successfully, a negative value
94 * if an error occurred.
95 */
96 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
97 const u64 *private_key, u64 *public_key);
98
99 /**
100 * crypto_ecdh_shared_secret() - Compute a shared secret
101 *
102 * @curve_id: id representing the curve to use
103 * @ndigits: curve's number of digits
104 * @private_key: private key of part A
105 * @public_key: public key of counterpart B
106 * @secret: buffer for storing the calculated shared secret
107 *
108 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
109 * before using it for symmetric encryption or HMAC.
110 *
111 * Returns 0 if the shared secret was generated successfully, a negative value
112 * if an error occurred.
113 */
114 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
115 const u64 *private_key, const u64 *public_key,
116 u64 *secret);
117
118 /**
119 * ecc_is_pubkey_valid_partial() - Partial public key validation
120 *
121 * @curve: elliptic curve domain parameters
122 * @pk: public key as a point
123 *
124 * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
125 * Public-Key Validation Routine.
126 *
127 * Note: There is no check that the public key is in the correct elliptic curve
128 * subgroup.
129 *
130 * Return: 0 if validation is successful, -EINVAL if validation is failed.
131 */
132 int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
133 struct ecc_point *pk);
134
135 /**
136 * ecc_is_pubkey_valid_full() - Full public key validation
137 *
138 * @curve: elliptic curve domain parameters
139 * @pk: public key as a point
140 *
141 * Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full
142 * Public-Key Validation Routine.
143 *
144 * Return: 0 if validation is successful, -EINVAL if validation is failed.
145 */
146 int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
147 struct ecc_point *pk);
148
149 /**
150 * vli_is_zero() - Determine is vli is zero
151 *
152 * @vli: vli to check.
153 * @ndigits: length of the @vli
154 */
155 bool vli_is_zero(const u64 *vli, unsigned int ndigits);
156
157 /**
158 * vli_cmp() - compare left and right vlis
159 *
160 * @left: vli
161 * @right: vli
162 * @ndigits: length of both vlis
163 *
164 * Returns sign of @left - @right, i.e. -1 if @left < @right,
165 * 0 if @left == @right, 1 if @left > @right.
166 */
167 int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits);
168
169 /**
170 * vli_sub() - Subtracts right from left
171 *
172 * @result: where to write result
173 * @left: vli
174 * @right vli
175 * @ndigits: length of all vlis
176 *
177 * Note: can modify in-place.
178 *
179 * Return: carry bit.
180 */
181 u64 vli_sub(u64 *result, const u64 *left, const u64 *right,
182 unsigned int ndigits);
183
184 /**
185 * vli_from_be64() - Load vli from big-endian u64 array
186 *
187 * @dest: destination vli
188 * @src: source array of u64 BE values
189 * @ndigits: length of both vli and array
190 */
191 void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits);
192
193 /**
194 * vli_from_le64() - Load vli from little-endian u64 array
195 *
196 * @dest: destination vli
197 * @src: source array of u64 LE values
198 * @ndigits: length of both vli and array
199 */
200 void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits);
201
202 /**
203 * vli_mod_inv() - Modular inversion
204 *
205 * @result: where to write vli number
206 * @input: vli value to operate on
207 * @mod: modulus
208 * @ndigits: length of all vlis
209 */
210 void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod,
211 unsigned int ndigits);
212
213 /**
214 * vli_mod_mult_slow() - Modular multiplication
215 *
216 * @result: where to write result value
217 * @left: vli number to multiply with @right
218 * @right: vli number to multiply with @left
219 * @mod: modulus
220 * @ndigits: length of all vlis
221 *
222 * Note: Assumes that mod is big enough curve order.
223 */
224 void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right,
225 const u64 *mod, unsigned int ndigits);
226
227 /**
228 * ecc_point_mult_shamir() - Add two points multiplied by scalars
229 *
230 * @result: resulting point
231 * @x: scalar to multiply with @p
232 * @p: point to multiply with @x
233 * @y: scalar to multiply with @q
234 * @q: point to multiply with @y
235 * @curve: curve
236 *
237 * Returns result = x * p + x * q over the curve.
238 * This works faster than two multiplications and addition.
239 */
240 void ecc_point_mult_shamir(const struct ecc_point *result,
241 const u64 *x, const struct ecc_point *p,
242 const u64 *y, const struct ecc_point *q,
243 const struct ecc_curve *curve);
244 #endif
245