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 */ 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_is_key_valid() - Validate a given ECDH private key 61 * 62 * @curve_id: id representing the curve to use 63 * @ndigits: curve's number of digits 64 * @private_key: private key to be used for the given curve 65 * @private_key_len: private key length 66 * 67 * Returns 0 if the key is acceptable, a negative value otherwise 68 */ 69 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, 70 const u64 *private_key, unsigned int private_key_len); 71 72 /** 73 * ecc_gen_privkey() - Generates an ECC private key. 74 * The private key is a random integer in the range 0 < random < n, where n is a 75 * prime that is the order of the cyclic subgroup generated by the distinguished 76 * point G. 77 * @curve_id: id representing the curve to use 78 * @ndigits: curve number of digits 79 * @private_key: buffer for storing the generated private key 80 * 81 * Returns 0 if the private key was generated successfully, a negative value 82 * if an error occurred. 83 */ 84 int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey); 85 86 /** 87 * ecc_make_pub_key() - Compute an ECC public key 88 * 89 * @curve_id: id representing the curve to use 90 * @ndigits: curve's number of digits 91 * @private_key: pregenerated private key for the given curve 92 * @public_key: buffer for storing the generated public key 93 * 94 * Returns 0 if the public key was generated successfully, a negative value 95 * if an error occurred. 96 */ 97 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits, 98 const u64 *private_key, u64 *public_key); 99 100 /** 101 * crypto_ecdh_shared_secret() - Compute a shared secret 102 * 103 * @curve_id: id representing the curve to use 104 * @ndigits: curve's number of digits 105 * @private_key: private key of part A 106 * @public_key: public key of counterpart B 107 * @secret: buffer for storing the calculated shared secret 108 * 109 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret 110 * before using it for symmetric encryption or HMAC. 111 * 112 * Returns 0 if the shared secret was generated successfully, a negative value 113 * if an error occurred. 114 */ 115 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, 116 const u64 *private_key, const u64 *public_key, 117 u64 *secret); 118 119 /** 120 * ecc_is_pubkey_valid_partial() - Partial public key validation 121 * 122 * @curve: elliptic curve domain parameters 123 * @pk: public key as a point 124 * 125 * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial 126 * Public-Key Validation Routine. 127 * 128 * Note: There is no check that the public key is in the correct elliptic curve 129 * subgroup. 130 * 131 * Return: 0 if validation is successful, -EINVAL if validation is failed. 132 */ 133 int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve, 134 struct ecc_point *pk); 135 136 /** 137 * ecc_is_pubkey_valid_full() - Full public key validation 138 * 139 * @curve: elliptic curve domain parameters 140 * @pk: public key as a point 141 * 142 * Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full 143 * Public-Key Validation Routine. 144 * 145 * Return: 0 if validation is successful, -EINVAL if validation is failed. 146 */ 147 int ecc_is_pubkey_valid_full(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 * vli_num_bits() - Counts the number of bits required for vli. 230 * 231 * @vli: vli to check. 232 * @ndigits: Length of the @vli 233 * 234 * Return: The number of bits required to represent @vli. 235 */ 236 unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits); 237 238 /** 239 * ecc_aloc_point() - Allocate ECC point. 240 * 241 * @ndigits: Length of vlis in u64 qwords. 242 * 243 * Return: Pointer to the allocated point or NULL if allocation failed. 244 */ 245 struct ecc_point *ecc_alloc_point(unsigned int ndigits); 246 247 /** 248 * ecc_free_point() - Free ECC point. 249 * 250 * @p: The point to free. 251 */ 252 void ecc_free_point(struct ecc_point *p); 253 254 /** 255 * ecc_point_is_zero() - Check if point is zero. 256 * 257 * @p: Point to check for zero. 258 * 259 * Return: true if point is the point at infinity, false otherwise. 260 */ 261 bool ecc_point_is_zero(const struct ecc_point *point); 262 263 /** 264 * ecc_point_mult_shamir() - Add two points multiplied by scalars 265 * 266 * @result: resulting point 267 * @x: scalar to multiply with @p 268 * @p: point to multiply with @x 269 * @y: scalar to multiply with @q 270 * @q: point to multiply with @y 271 * @curve: curve 272 * 273 * Returns result = x * p + x * q over the curve. 274 * This works faster than two multiplications and addition. 275 */ 276 void ecc_point_mult_shamir(const struct ecc_point *result, 277 const u64 *x, const struct ecc_point *p, 278 const u64 *y, const struct ecc_point *q, 279 const struct ecc_curve *curve); 280 281 #endif 282