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 * The integers r and s making up the signature are expected to be 47 * formatted as two consecutive u64 arrays of size ECC_MAX_BYTES. 48 * The bytes within each u64 digit are in native endianness, 49 * but the order of the u64 digits themselves is little endian. 50 * This format allows direct use by internal vli_*() functions. 51 */ 52 struct ecdsa_raw_sig { 53 u64 r[ECC_MAX_DIGITS]; 54 u64 s[ECC_MAX_DIGITS]; 55 }; 56 57 /** 58 * ecc_swap_digits() - Copy ndigits from big endian array to native array 59 * @in: Input array 60 * @out: Output array 61 * @ndigits: Number of digits to copy 62 */ 63 static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigits) 64 { 65 const __be64 *src = (__force __be64 *)in; 66 int i; 67 68 for (i = 0; i < ndigits; i++) 69 out[i] = get_unaligned_be64(&src[ndigits - 1 - i]); 70 } 71 72 /** 73 * ecc_digits_from_bytes() - Create ndigits-sized digits array from byte array 74 * @in: Input byte array 75 * @nbytes: Size of input byte array 76 * @out: Output digits array 77 * @ndigits: Number of digits to create from byte array 78 * 79 * The first byte in the input byte array is expected to hold the most 80 * significant bits of the large integer. 81 */ 82 void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes, 83 u64 *out, unsigned int ndigits); 84 85 /** 86 * ecc_is_key_valid() - Validate a given ECDH private key 87 * 88 * @curve_id: id representing the curve to use 89 * @ndigits: curve's number of digits 90 * @private_key: private key to be used for the given curve 91 * @private_key_len: private key length 92 * 93 * Returns: 0 if the key is acceptable, a negative value otherwise 94 */ 95 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, 96 const u64 *private_key, unsigned int private_key_len); 97 98 /** 99 * ecc_gen_privkey() - Generates an ECC private key. 100 * The private key is a random integer in the range 0 < random < n, where n is a 101 * prime that is the order of the cyclic subgroup generated by the distinguished 102 * point G. 103 * @curve_id: id representing the curve to use 104 * @ndigits: curve number of digits 105 * @private_key: buffer for storing the generated private key 106 * 107 * Returns: 0 if the private key was generated successfully, a negative value 108 * if an error occurred. 109 */ 110 int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, 111 u64 *private_key); 112 113 /** 114 * ecc_make_pub_key() - Compute an ECC public key 115 * 116 * @curve_id: id representing the curve to use 117 * @ndigits: curve's number of digits 118 * @private_key: pregenerated private key for the given curve 119 * @public_key: buffer for storing the generated public key 120 * 121 * Returns: 0 if the public key was generated successfully, a negative value 122 * if an error occurred. 123 */ 124 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits, 125 const u64 *private_key, u64 *public_key); 126 127 /** 128 * crypto_ecdh_shared_secret() - Compute a shared secret 129 * 130 * @curve_id: id representing the curve to use 131 * @ndigits: curve's number of digits 132 * @private_key: private key of part A 133 * @public_key: public key of counterpart B 134 * @secret: buffer for storing the calculated shared secret 135 * 136 * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret 137 * before using it for symmetric encryption or HMAC. 138 * 139 * Returns: 0 if the shared secret was generated successfully, a negative value 140 * if an error occurred. 141 */ 142 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, 143 const u64 *private_key, const u64 *public_key, 144 u64 *secret); 145 146 /** 147 * ecc_is_pubkey_valid_partial() - Partial public key validation 148 * 149 * @curve: elliptic curve domain parameters 150 * @pk: public key as a point 151 * 152 * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial 153 * Public-Key Validation Routine. 154 * 155 * Note: There is no check that the public key is in the correct elliptic curve 156 * subgroup. 157 * 158 * Return: 0 if validation is successful, -EINVAL if validation is failed. 159 */ 160 int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve, 161 struct ecc_point *pk); 162 163 /** 164 * ecc_is_pubkey_valid_full() - Full public key validation 165 * 166 * @curve: elliptic curve domain parameters 167 * @pk: public key as a point 168 * 169 * Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full 170 * Public-Key Validation Routine. 171 * 172 * Return: 0 if validation is successful, -EINVAL if validation is failed. 173 */ 174 int ecc_is_pubkey_valid_full(const struct ecc_curve *curve, 175 struct ecc_point *pk); 176 177 /** 178 * vli_is_zero() - Determine is vli is zero 179 * 180 * @vli: vli to check. 181 * @ndigits: length of the @vli 182 * 183 * Returns: %true if vli == 0, %false otherwise. 184 */ 185 bool vli_is_zero(const u64 *vli, unsigned int ndigits); 186 187 /** 188 * vli_cmp() - compare left and right vlis 189 * 190 * @left: vli 191 * @right: vli 192 * @ndigits: length of both vlis 193 * 194 * Returns: sign of @left - @right, i.e. -1 if @left < @right, 195 * 0 if @left == @right, 1 if @left > @right. 196 */ 197 int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits); 198 199 /** 200 * vli_sub() - Subtracts right from left 201 * 202 * @result: where to write result 203 * @left: vli 204 * @right: vli 205 * @ndigits: length of all vlis 206 * 207 * Note: can modify in-place. 208 * 209 * Return: carry bit. 210 */ 211 u64 vli_sub(u64 *result, const u64 *left, const u64 *right, 212 unsigned int ndigits); 213 214 /** 215 * vli_from_be64() - Load vli from big-endian u64 array 216 * 217 * @dest: destination vli 218 * @src: source array of u64 BE values 219 * @ndigits: length of both vli and array 220 */ 221 void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits); 222 223 /** 224 * vli_from_le64() - Load vli from little-endian u64 array 225 * 226 * @dest: destination vli 227 * @src: source array of u64 LE values 228 * @ndigits: length of both vli and array 229 */ 230 void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits); 231 232 /** 233 * vli_mod_inv() - Modular inversion 234 * 235 * @result: where to write vli number 236 * @input: vli value to operate on 237 * @mod: modulus 238 * @ndigits: length of all vlis 239 */ 240 void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod, 241 unsigned int ndigits); 242 243 /** 244 * vli_mod_mult_slow() - Modular multiplication 245 * 246 * @result: where to write result value 247 * @left: vli number to multiply with @right 248 * @right: vli number to multiply with @left 249 * @mod: modulus 250 * @ndigits: length of all vlis 251 * 252 * Note: Assumes that mod is big enough curve order. 253 */ 254 void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right, 255 const u64 *mod, unsigned int ndigits); 256 257 /** 258 * vli_num_bits() - Counts the number of bits required for vli. 259 * 260 * @vli: vli to check. 261 * @ndigits: Length of the @vli 262 * 263 * Return: The number of bits required to represent @vli. 264 */ 265 unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits); 266 267 /** 268 * ecc_alloc_point() - Allocate ECC point. 269 * 270 * @ndigits: Length of vlis in u64 qwords. 271 * 272 * Return: Pointer to the allocated point or NULL if allocation failed. 273 */ 274 struct ecc_point *ecc_alloc_point(unsigned int ndigits); 275 276 /** 277 * ecc_free_point() - Free ECC point. 278 * 279 * @p: The point to free. 280 */ 281 void ecc_free_point(struct ecc_point *p); 282 283 /** 284 * ecc_point_is_zero() - Check if point is zero. 285 * 286 * @point: Point to check for zero. 287 * 288 * Return: true if point is the point at infinity, false otherwise. 289 */ 290 bool ecc_point_is_zero(const struct ecc_point *point); 291 292 /** 293 * ecc_point_mult_shamir() - Add two points multiplied by scalars 294 * 295 * @result: resulting point 296 * @x: scalar to multiply with @p 297 * @p: point to multiply with @x 298 * @y: scalar to multiply with @q 299 * @q: point to multiply with @y 300 * @curve: curve 301 * 302 * Returns result = x * p + x * q over the curve. 303 * This works faster than two multiplications and addition. 304 */ 305 void ecc_point_mult_shamir(const struct ecc_point *result, 306 const u64 *x, const struct ecc_point *p, 307 const u64 *y, const struct ecc_point *q, 308 const struct ecc_curve *curve); 309 310 extern struct crypto_template ecdsa_x962_tmpl; 311 extern struct crypto_template ecdsa_p1363_tmpl; 312 #endif 313