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/* One digit is u64 qword. */ 30#define ECC_CURVE_NIST_P192_DIGITS 3 31#define ECC_CURVE_NIST_P256_DIGITS 4 32#define ECC_CURVE_NIST_P384_DIGITS 6 33#define ECC_MAX_DIGITS (512 / 64) /* due to ecrdsa */ 34 35#define ECC_DIGITS_TO_BYTES_SHIFT 3 36 37#define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT) 38 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 */ 46struct ecc_point { 47 u64 *x; 48 u64 *y; 49 u8 ndigits; 50}; 51 52#define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits } 53 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 */ 67struct ecc_curve { 68 char *name; 69 struct ecc_point g; 70 u64 *p; 71 u64 *n; 72 u64 *a; 73 u64 *b; 74}; 75 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 */ 82static 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 */ 97const struct ecc_curve *ecc_get_curve(unsigned int curve_id); 98 99/** 100 * ecc_is_key_valid() - Validate a given ECDH private key 101 * 102 * @curve_id: id representing the curve to use 103 * @ndigits: curve's number of digits 104 * @private_key: private key to be used for the given curve 105 * @private_key_len: private key length 106 * 107 * Returns 0 if the key is acceptable, a negative value otherwise 108 */ 109int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, 110 const u64 *private_key, unsigned int private_key_len); 111 112/** 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 */ 124int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey); 125 126/** 127 * ecc_make_pub_key() - Compute an ECC public key 128 * 129 * @curve_id: id representing the curve to use 130 * @ndigits: curve's number of digits 131 * @private_key: pregenerated private key for the given curve 132 * @public_key: buffer for storing the generated public key 133 * 134 * Returns 0 if the public key was generated successfully, a negative value 135 * if an error occurred. 136 */ 137int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits, 138 const u64 *private_key, u64 *public_key); 139 140/** 141 * crypto_ecdh_shared_secret() - Compute a shared secret 142 * 143 * @curve_id: id representing the curve to use 144 * @ndigits: curve's number of digits 145 * @private_key: private key of part A 146 * @public_key: public key of counterpart B 147 * @secret: buffer for storing the calculated shared secret 148 * 149 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret 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 */ 155int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, 156 const u64 *private_key, const u64 *public_key, 157 u64 *secret); 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 */ 173int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve, 174 struct ecc_point *pk); 175 176/** 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 */ 187int ecc_is_pubkey_valid_full(const struct ecc_curve *curve, 188 struct ecc_point *pk); 189 190/** 191 * vli_is_zero() - Determine is vli is zero 192 * 193 * @vli: vli to check. 194 * @ndigits: length of the @vli 195 */ 196bool 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 */ 208int 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 */ 222u64 vli_sub(u64 *result, const u64 *left, const u64 *right, 223 unsigned int ndigits); 224 225/** 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 */ 232void 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 */ 241void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits); 242 243/** 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 */ 251void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod, 252 unsigned int ndigits); 253 254/** 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 */ 265void 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 */ 281void 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); 285#endif 286