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 bool vli_is_zero(const u64 *vli, unsigned int ndigits); 184 185 /** 186 * vli_cmp() - compare left and right vlis 187 * 188 * @left: vli 189 * @right: vli 190 * @ndigits: length of both vlis 191 * 192 * Returns sign of @left - @right, i.e. -1 if @left < @right, 193 * 0 if @left == @right, 1 if @left > @right. 194 */ 195 int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits); 196 197 /** 198 * vli_sub() - Subtracts right from left 199 * 200 * @result: where to write result 201 * @left: vli 202 * @right vli 203 * @ndigits: length of all vlis 204 * 205 * Note: can modify in-place. 206 * 207 * Return: carry bit. 208 */ 209 u64 vli_sub(u64 *result, const u64 *left, const u64 *right, 210 unsigned int ndigits); 211 212 /** 213 * vli_from_be64() - Load vli from big-endian u64 array 214 * 215 * @dest: destination vli 216 * @src: source array of u64 BE values 217 * @ndigits: length of both vli and array 218 */ 219 void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits); 220 221 /** 222 * vli_from_le64() - Load vli from little-endian u64 array 223 * 224 * @dest: destination vli 225 * @src: source array of u64 LE values 226 * @ndigits: length of both vli and array 227 */ 228 void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits); 229 230 /** 231 * vli_mod_inv() - Modular inversion 232 * 233 * @result: where to write vli number 234 * @input: vli value to operate on 235 * @mod: modulus 236 * @ndigits: length of all vlis 237 */ 238 void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod, 239 unsigned int ndigits); 240 241 /** 242 * vli_mod_mult_slow() - Modular multiplication 243 * 244 * @result: where to write result value 245 * @left: vli number to multiply with @right 246 * @right: vli number to multiply with @left 247 * @mod: modulus 248 * @ndigits: length of all vlis 249 * 250 * Note: Assumes that mod is big enough curve order. 251 */ 252 void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right, 253 const u64 *mod, unsigned int ndigits); 254 255 /** 256 * vli_num_bits() - Counts the number of bits required for vli. 257 * 258 * @vli: vli to check. 259 * @ndigits: Length of the @vli 260 * 261 * Return: The number of bits required to represent @vli. 262 */ 263 unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits); 264 265 /** 266 * ecc_aloc_point() - Allocate ECC point. 267 * 268 * @ndigits: Length of vlis in u64 qwords. 269 * 270 * Return: Pointer to the allocated point or NULL if allocation failed. 271 */ 272 struct ecc_point *ecc_alloc_point(unsigned int ndigits); 273 274 /** 275 * ecc_free_point() - Free ECC point. 276 * 277 * @p: The point to free. 278 */ 279 void ecc_free_point(struct ecc_point *p); 280 281 /** 282 * ecc_point_is_zero() - Check if point is zero. 283 * 284 * @p: Point to check for zero. 285 * 286 * Return: true if point is the point at infinity, false otherwise. 287 */ 288 bool ecc_point_is_zero(const struct ecc_point *point); 289 290 /** 291 * ecc_point_mult_shamir() - Add two points multiplied by scalars 292 * 293 * @result: resulting point 294 * @x: scalar to multiply with @p 295 * @p: point to multiply with @x 296 * @y: scalar to multiply with @q 297 * @q: point to multiply with @y 298 * @curve: curve 299 * 300 * Returns result = x * p + x * q over the curve. 301 * This works faster than two multiplications and addition. 302 */ 303 void ecc_point_mult_shamir(const struct ecc_point *result, 304 const u64 *x, const struct ecc_point *p, 305 const u64 *y, const struct ecc_point *q, 306 const struct ecc_curve *curve); 307 308 extern struct crypto_template ecdsa_x962_tmpl; 309 extern struct crypto_template ecdsa_p1363_tmpl; 310 #endif 311