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_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 void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes, 68 u64 *out, unsigned int ndigits); 69 70 /** 71 * ecc_is_key_valid() - Validate a given ECDH private key 72 * 73 * @curve_id: id representing the curve to use 74 * @ndigits: curve's number of digits 75 * @private_key: private key to be used for the given curve 76 * @private_key_len: private key length 77 * 78 * Returns 0 if the key is acceptable, a negative value otherwise 79 */ 80 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, 81 const u64 *private_key, unsigned int private_key_len); 82 83 /** 84 * ecc_gen_privkey() - Generates an ECC private key. 85 * The private key is a random integer in the range 0 < random < n, where n is a 86 * prime that is the order of the cyclic subgroup generated by the distinguished 87 * point G. 88 * @curve_id: id representing the curve to use 89 * @ndigits: curve number of digits 90 * @private_key: buffer for storing the generated private key 91 * 92 * Returns 0 if the private key was generated successfully, a negative value 93 * if an error occurred. 94 */ 95 int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, 96 u64 *private_key); 97 98 /** 99 * ecc_make_pub_key() - Compute an ECC public key 100 * 101 * @curve_id: id representing the curve to use 102 * @ndigits: curve's number of digits 103 * @private_key: pregenerated private key for the given curve 104 * @public_key: buffer for storing the generated public key 105 * 106 * Returns 0 if the public key was generated successfully, a negative value 107 * if an error occurred. 108 */ 109 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits, 110 const u64 *private_key, u64 *public_key); 111 112 /** 113 * crypto_ecdh_shared_secret() - Compute a shared secret 114 * 115 * @curve_id: id representing the curve to use 116 * @ndigits: curve's number of digits 117 * @private_key: private key of part A 118 * @public_key: public key of counterpart B 119 * @secret: buffer for storing the calculated shared secret 120 * 121 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret 122 * before using it for symmetric encryption or HMAC. 123 * 124 * Returns 0 if the shared secret was generated successfully, a negative value 125 * if an error occurred. 126 */ 127 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, 128 const u64 *private_key, const u64 *public_key, 129 u64 *secret); 130 131 /** 132 * ecc_is_pubkey_valid_partial() - Partial public key validation 133 * 134 * @curve: elliptic curve domain parameters 135 * @pk: public key as a point 136 * 137 * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial 138 * Public-Key Validation Routine. 139 * 140 * Note: There is no check that the public key is in the correct elliptic curve 141 * subgroup. 142 * 143 * Return: 0 if validation is successful, -EINVAL if validation is failed. 144 */ 145 int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve, 146 struct ecc_point *pk); 147 148 /** 149 * ecc_is_pubkey_valid_full() - Full public key validation 150 * 151 * @curve: elliptic curve domain parameters 152 * @pk: public key as a point 153 * 154 * Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full 155 * Public-Key Validation Routine. 156 * 157 * Return: 0 if validation is successful, -EINVAL if validation is failed. 158 */ 159 int ecc_is_pubkey_valid_full(const struct ecc_curve *curve, 160 struct ecc_point *pk); 161 162 /** 163 * vli_is_zero() - Determine is vli is zero 164 * 165 * @vli: vli to check. 166 * @ndigits: length of the @vli 167 */ 168 bool vli_is_zero(const u64 *vli, unsigned int ndigits); 169 170 /** 171 * vli_cmp() - compare left and right vlis 172 * 173 * @left: vli 174 * @right: vli 175 * @ndigits: length of both vlis 176 * 177 * Returns sign of @left - @right, i.e. -1 if @left < @right, 178 * 0 if @left == @right, 1 if @left > @right. 179 */ 180 int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits); 181 182 /** 183 * vli_sub() - Subtracts right from left 184 * 185 * @result: where to write result 186 * @left: vli 187 * @right vli 188 * @ndigits: length of all vlis 189 * 190 * Note: can modify in-place. 191 * 192 * Return: carry bit. 193 */ 194 u64 vli_sub(u64 *result, const u64 *left, const u64 *right, 195 unsigned int ndigits); 196 197 /** 198 * vli_from_be64() - Load vli from big-endian u64 array 199 * 200 * @dest: destination vli 201 * @src: source array of u64 BE values 202 * @ndigits: length of both vli and array 203 */ 204 void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits); 205 206 /** 207 * vli_from_le64() - Load vli from little-endian u64 array 208 * 209 * @dest: destination vli 210 * @src: source array of u64 LE values 211 * @ndigits: length of both vli and array 212 */ 213 void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits); 214 215 /** 216 * vli_mod_inv() - Modular inversion 217 * 218 * @result: where to write vli number 219 * @input: vli value to operate on 220 * @mod: modulus 221 * @ndigits: length of all vlis 222 */ 223 void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod, 224 unsigned int ndigits); 225 226 /** 227 * vli_mod_mult_slow() - Modular multiplication 228 * 229 * @result: where to write result value 230 * @left: vli number to multiply with @right 231 * @right: vli number to multiply with @left 232 * @mod: modulus 233 * @ndigits: length of all vlis 234 * 235 * Note: Assumes that mod is big enough curve order. 236 */ 237 void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right, 238 const u64 *mod, unsigned int ndigits); 239 240 /** 241 * vli_num_bits() - Counts the number of bits required for vli. 242 * 243 * @vli: vli to check. 244 * @ndigits: Length of the @vli 245 * 246 * Return: The number of bits required to represent @vli. 247 */ 248 unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits); 249 250 /** 251 * ecc_aloc_point() - Allocate ECC point. 252 * 253 * @ndigits: Length of vlis in u64 qwords. 254 * 255 * Return: Pointer to the allocated point or NULL if allocation failed. 256 */ 257 struct ecc_point *ecc_alloc_point(unsigned int ndigits); 258 259 /** 260 * ecc_free_point() - Free ECC point. 261 * 262 * @p: The point to free. 263 */ 264 void ecc_free_point(struct ecc_point *p); 265 266 /** 267 * ecc_point_is_zero() - Check if point is zero. 268 * 269 * @p: Point to check for zero. 270 * 271 * Return: true if point is the point at infinity, false otherwise. 272 */ 273 bool ecc_point_is_zero(const struct ecc_point *point); 274 275 /** 276 * ecc_point_mult_shamir() - Add two points multiplied by scalars 277 * 278 * @result: resulting point 279 * @x: scalar to multiply with @p 280 * @p: point to multiply with @x 281 * @y: scalar to multiply with @q 282 * @q: point to multiply with @y 283 * @curve: curve 284 * 285 * Returns result = x * p + x * q over the curve. 286 * This works faster than two multiplications and addition. 287 */ 288 void ecc_point_mult_shamir(const struct ecc_point *result, 289 const u64 *x, const struct ecc_point *p, 290 const u64 *y, const struct ecc_point *q, 291 const struct ecc_curve *curve); 292 293 #endif 294