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 <linux/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 */ 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 * The first byte in the input byte array is expected to hold the most 68 * significant bits of the large integer. 69 */ 70 void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes, 71 u64 *out, unsigned int ndigits); 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, 99 u64 *private_key); 100 101 /** 102 * ecc_make_pub_key() - Compute an ECC public key 103 * 104 * @curve_id: id representing the curve to use 105 * @ndigits: curve's number of digits 106 * @private_key: pregenerated private key for the given curve 107 * @public_key: buffer for storing the generated public key 108 * 109 * Returns 0 if the public key was generated successfully, a negative value 110 * if an error occurred. 111 */ 112 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits, 113 const u64 *private_key, u64 *public_key); 114 115 /** 116 * crypto_ecdh_shared_secret() - Compute a shared secret 117 * 118 * @curve_id: id representing the curve to use 119 * @ndigits: curve's number of digits 120 * @private_key: private key of part A 121 * @public_key: public key of counterpart B 122 * @secret: buffer for storing the calculated shared secret 123 * 124 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret 125 * before using it for symmetric encryption or HMAC. 126 * 127 * Returns 0 if the shared secret was generated successfully, a negative value 128 * if an error occurred. 129 */ 130 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, 131 const u64 *private_key, const u64 *public_key, 132 u64 *secret); 133 134 /** 135 * ecc_is_pubkey_valid_partial() - Partial public key validation 136 * 137 * @curve: elliptic curve domain parameters 138 * @pk: public key as a point 139 * 140 * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial 141 * Public-Key Validation Routine. 142 * 143 * Note: There is no check that the public key is in the correct elliptic curve 144 * subgroup. 145 * 146 * Return: 0 if validation is successful, -EINVAL if validation is failed. 147 */ 148 int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve, 149 struct ecc_point *pk); 150 151 /** 152 * ecc_is_pubkey_valid_full() - Full public key validation 153 * 154 * @curve: elliptic curve domain parameters 155 * @pk: public key as a point 156 * 157 * Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full 158 * Public-Key Validation Routine. 159 * 160 * Return: 0 if validation is successful, -EINVAL if validation is failed. 161 */ 162 int ecc_is_pubkey_valid_full(const struct ecc_curve *curve, 163 struct ecc_point *pk); 164 165 /** 166 * vli_is_zero() - Determine is vli is zero 167 * 168 * @vli: vli to check. 169 * @ndigits: length of the @vli 170 */ 171 bool vli_is_zero(const u64 *vli, unsigned int ndigits); 172 173 /** 174 * vli_cmp() - compare left and right vlis 175 * 176 * @left: vli 177 * @right: vli 178 * @ndigits: length of both vlis 179 * 180 * Returns sign of @left - @right, i.e. -1 if @left < @right, 181 * 0 if @left == @right, 1 if @left > @right. 182 */ 183 int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits); 184 185 /** 186 * vli_sub() - Subtracts right from left 187 * 188 * @result: where to write result 189 * @left: vli 190 * @right vli 191 * @ndigits: length of all vlis 192 * 193 * Note: can modify in-place. 194 * 195 * Return: carry bit. 196 */ 197 u64 vli_sub(u64 *result, const u64 *left, const u64 *right, 198 unsigned int ndigits); 199 200 /** 201 * vli_from_be64() - Load vli from big-endian u64 array 202 * 203 * @dest: destination vli 204 * @src: source array of u64 BE values 205 * @ndigits: length of both vli and array 206 */ 207 void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits); 208 209 /** 210 * vli_from_le64() - Load vli from little-endian u64 array 211 * 212 * @dest: destination vli 213 * @src: source array of u64 LE values 214 * @ndigits: length of both vli and array 215 */ 216 void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits); 217 218 /** 219 * vli_mod_inv() - Modular inversion 220 * 221 * @result: where to write vli number 222 * @input: vli value to operate on 223 * @mod: modulus 224 * @ndigits: length of all vlis 225 */ 226 void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod, 227 unsigned int ndigits); 228 229 /** 230 * vli_mod_mult_slow() - Modular multiplication 231 * 232 * @result: where to write result value 233 * @left: vli number to multiply with @right 234 * @right: vli number to multiply with @left 235 * @mod: modulus 236 * @ndigits: length of all vlis 237 * 238 * Note: Assumes that mod is big enough curve order. 239 */ 240 void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right, 241 const u64 *mod, unsigned int ndigits); 242 243 /** 244 * vli_num_bits() - Counts the number of bits required for vli. 245 * 246 * @vli: vli to check. 247 * @ndigits: Length of the @vli 248 * 249 * Return: The number of bits required to represent @vli. 250 */ 251 unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits); 252 253 /** 254 * ecc_aloc_point() - Allocate ECC point. 255 * 256 * @ndigits: Length of vlis in u64 qwords. 257 * 258 * Return: Pointer to the allocated point or NULL if allocation failed. 259 */ 260 struct ecc_point *ecc_alloc_point(unsigned int ndigits); 261 262 /** 263 * ecc_free_point() - Free ECC point. 264 * 265 * @p: The point to free. 266 */ 267 void ecc_free_point(struct ecc_point *p); 268 269 /** 270 * ecc_point_is_zero() - Check if point is zero. 271 * 272 * @p: Point to check for zero. 273 * 274 * Return: true if point is the point at infinity, false otherwise. 275 */ 276 bool ecc_point_is_zero(const struct ecc_point *point); 277 278 /** 279 * ecc_point_mult_shamir() - Add two points multiplied by scalars 280 * 281 * @result: resulting point 282 * @x: scalar to multiply with @p 283 * @p: point to multiply with @x 284 * @y: scalar to multiply with @q 285 * @q: point to multiply with @y 286 * @curve: curve 287 * 288 * Returns result = x * p + x * q over the curve. 289 * This works faster than two multiplications and addition. 290 */ 291 void ecc_point_mult_shamir(const struct ecc_point *result, 292 const u64 *x, const struct ecc_point *p, 293 const u64 *y, const struct ecc_point *q, 294 const struct ecc_curve *curve); 295 296 #endif 297