include/crypto/internal/ecc.h

   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