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_MAX_DIGITS (512 / 64) 33 34 #define ECC_DIGITS_TO_BYTES_SHIFT 3 35 36 /** 37 * struct ecc_point - elliptic curve point in affine coordinates 38 * 39 * @x: X coordinate in vli form. 40 * @y: Y coordinate in vli form. 41 * @ndigits: Length of vlis in u64 qwords. 42 */ 43 struct ecc_point { 44 u64 *x; 45 u64 *y; 46 u8 ndigits; 47 }; 48 49 #define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits } 50 51 /** 52 * struct ecc_curve - definition of elliptic curve 53 * 54 * @name: Short name of the curve. 55 * @g: Generator point of the curve. 56 * @p: Prime number, if Barrett's reduction is used for this curve 57 * pre-calculated value 'mu' is appended to the @p after ndigits. 58 * Use of Barrett's reduction is heuristically determined in 59 * vli_mmod_fast(). 60 * @n: Order of the curve group. 61 * @a: Curve parameter a. 62 * @b: Curve parameter b. 63 */ 64 struct ecc_curve { 65 char *name; 66 struct ecc_point g; 67 u64 *p; 68 u64 *n; 69 u64 *a; 70 u64 *b; 71 }; 72 73 /** 74 * ecc_is_key_valid() - Validate a given ECDH private key 75 * 76 * @curve_id: id representing the curve to use 77 * @ndigits: curve's number of digits 78 * @private_key: private key to be used for the given curve 79 * @private_key_len: private key length 80 * 81 * Returns 0 if the key is acceptable, a negative value otherwise 82 */ 83 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, 84 const u64 *private_key, unsigned int private_key_len); 85 86 /** 87 * ecc_gen_privkey() - Generates an ECC private key. 88 * The private key is a random integer in the range 0 < random < n, where n is a 89 * prime that is the order of the cyclic subgroup generated by the distinguished 90 * point G. 91 * @curve_id: id representing the curve to use 92 * @ndigits: curve number of digits 93 * @private_key: buffer for storing the generated private key 94 * 95 * Returns 0 if the private key was generated successfully, a negative value 96 * if an error occurred. 97 */ 98 int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey); 99 100 /** 101 * ecc_make_pub_key() - Compute an ECC public key 102 * 103 * @curve_id: id representing the curve to use 104 * @ndigits: curve's number of digits 105 * @private_key: pregenerated private key for the given curve 106 * @public_key: buffer for storing the generated public key 107 * 108 * Returns 0 if the public key was generated successfully, a negative value 109 * if an error occurred. 110 */ 111 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits, 112 const u64 *private_key, u64 *public_key); 113 114 /** 115 * crypto_ecdh_shared_secret() - Compute a shared secret 116 * 117 * @curve_id: id representing the curve to use 118 * @ndigits: curve's number of digits 119 * @private_key: private key of part A 120 * @public_key: public key of counterpart B 121 * @secret: buffer for storing the calculated shared secret 122 * 123 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret 124 * before using it for symmetric encryption or HMAC. 125 * 126 * Returns 0 if the shared secret was generated successfully, a negative value 127 * if an error occurred. 128 */ 129 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, 130 const u64 *private_key, const u64 *public_key, 131 u64 *secret); 132 133 /** 134 * ecc_is_pubkey_valid_partial() - Partial public key validation 135 * 136 * @curve: elliptic curve domain parameters 137 * @pk: public key as a point 138 * 139 * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial 140 * Public-Key Validation Routine. 141 * 142 * Note: There is no check that the public key is in the correct elliptic curve 143 * subgroup. 144 * 145 * Return: 0 if validation is successful, -EINVAL if validation is failed. 146 */ 147 int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve, 148 struct ecc_point *pk); 149 150 /** 151 * vli_is_zero() - Determine is vli is zero 152 * 153 * @vli: vli to check. 154 * @ndigits: length of the @vli 155 */ 156 bool vli_is_zero(const u64 *vli, unsigned int ndigits); 157 158 /** 159 * vli_cmp() - compare left and right vlis 160 * 161 * @left: vli 162 * @right: vli 163 * @ndigits: length of both vlis 164 * 165 * Returns sign of @left - @right, i.e. -1 if @left < @right, 166 * 0 if @left == @right, 1 if @left > @right. 167 */ 168 int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits); 169 170 /** 171 * vli_sub() - Subtracts right from left 172 * 173 * @result: where to write result 174 * @left: vli 175 * @right vli 176 * @ndigits: length of all vlis 177 * 178 * Note: can modify in-place. 179 * 180 * Return: carry bit. 181 */ 182 u64 vli_sub(u64 *result, const u64 *left, const u64 *right, 183 unsigned int ndigits); 184 185 /** 186 * vli_from_be64() - Load vli from big-endian u64 array 187 * 188 * @dest: destination vli 189 * @src: source array of u64 BE values 190 * @ndigits: length of both vli and array 191 */ 192 void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits); 193 194 /** 195 * vli_from_le64() - Load vli from little-endian u64 array 196 * 197 * @dest: destination vli 198 * @src: source array of u64 LE values 199 * @ndigits: length of both vli and array 200 */ 201 void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits); 202 203 /** 204 * vli_mod_inv() - Modular inversion 205 * 206 * @result: where to write vli number 207 * @input: vli value to operate on 208 * @mod: modulus 209 * @ndigits: length of all vlis 210 */ 211 void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod, 212 unsigned int ndigits); 213 214 /** 215 * vli_mod_mult_slow() - Modular multiplication 216 * 217 * @result: where to write result value 218 * @left: vli number to multiply with @right 219 * @right: vli number to multiply with @left 220 * @mod: modulus 221 * @ndigits: length of all vlis 222 * 223 * Note: Assumes that mod is big enough curve order. 224 */ 225 void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right, 226 const u64 *mod, unsigned int ndigits); 227 228 /** 229 * ecc_point_mult_shamir() - Add two points multiplied by scalars 230 * 231 * @result: resulting point 232 * @x: scalar to multiply with @p 233 * @p: point to multiply with @x 234 * @y: scalar to multiply with @q 235 * @q: point to multiply with @y 236 * @curve: curve 237 * 238 * Returns result = x * p + x * q over the curve. 239 * This works faster than two multiplications and addition. 240 */ 241 void ecc_point_mult_shamir(const struct ecc_point *result, 242 const u64 *x, const struct ecc_point *p, 243 const u64 *y, const struct ecc_point *q, 244 const struct ecc_curve *curve); 245 #endif 246