ecc.h 8.6 KB

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  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. #include <crypto/ecc_curve.h>
  29. #include <asm/unaligned.h>
  30. /* One digit is u64 qword. */
  31. #define ECC_CURVE_NIST_P192_DIGITS 3
  32. #define ECC_CURVE_NIST_P256_DIGITS 4
  33. #define ECC_CURVE_NIST_P384_DIGITS 6
  34. #define ECC_MAX_DIGITS (512 / 64) /* due to ecrdsa */
  35. #define ECC_DIGITS_TO_BYTES_SHIFT 3
  36. #define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
  37. #define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
  38. /**
  39. * ecc_swap_digits() - Copy ndigits from big endian array to native array
  40. * @in: Input array
  41. * @out: Output array
  42. * @ndigits: Number of digits to copy
  43. */
  44. static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigits)
  45. {
  46. const __be64 *src = (__force __be64 *)in;
  47. int i;
  48. for (i = 0; i < ndigits; i++)
  49. out[i] = get_unaligned_be64(&src[ndigits - 1 - i]);
  50. }
  51. /**
  52. * ecc_is_key_valid() - Validate a given ECDH private key
  53. *
  54. * @curve_id: id representing the curve to use
  55. * @ndigits: curve's number of digits
  56. * @private_key: private key to be used for the given curve
  57. * @private_key_len: private key length
  58. *
  59. * Returns 0 if the key is acceptable, a negative value otherwise
  60. */
  61. int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
  62. const u64 *private_key, unsigned int private_key_len);
  63. /**
  64. * ecc_gen_privkey() - Generates an ECC private key.
  65. * The private key is a random integer in the range 0 < random < n, where n is a
  66. * prime that is the order of the cyclic subgroup generated by the distinguished
  67. * point G.
  68. * @curve_id: id representing the curve to use
  69. * @ndigits: curve number of digits
  70. * @private_key: buffer for storing the generated private key
  71. *
  72. * Returns 0 if the private key was generated successfully, a negative value
  73. * if an error occurred.
  74. */
  75. int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
  76. /**
  77. * ecc_make_pub_key() - Compute an ECC public key
  78. *
  79. * @curve_id: id representing the curve to use
  80. * @ndigits: curve's number of digits
  81. * @private_key: pregenerated private key for the given curve
  82. * @public_key: buffer for storing the generated public key
  83. *
  84. * Returns 0 if the public key was generated successfully, a negative value
  85. * if an error occurred.
  86. */
  87. int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
  88. const u64 *private_key, u64 *public_key);
  89. /**
  90. * crypto_ecdh_shared_secret() - Compute a shared secret
  91. *
  92. * @curve_id: id representing the curve to use
  93. * @ndigits: curve's number of digits
  94. * @private_key: private key of part A
  95. * @public_key: public key of counterpart B
  96. * @secret: buffer for storing the calculated shared secret
  97. *
  98. * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
  99. * before using it for symmetric encryption or HMAC.
  100. *
  101. * Returns 0 if the shared secret was generated successfully, a negative value
  102. * if an error occurred.
  103. */
  104. int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
  105. const u64 *private_key, const u64 *public_key,
  106. u64 *secret);
  107. /**
  108. * ecc_is_pubkey_valid_partial() - Partial public key validation
  109. *
  110. * @curve: elliptic curve domain parameters
  111. * @pk: public key as a point
  112. *
  113. * Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
  114. * Public-Key Validation Routine.
  115. *
  116. * Note: There is no check that the public key is in the correct elliptic curve
  117. * subgroup.
  118. *
  119. * Return: 0 if validation is successful, -EINVAL if validation is failed.
  120. */
  121. int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
  122. struct ecc_point *pk);
  123. /**
  124. * ecc_is_pubkey_valid_full() - Full public key validation
  125. *
  126. * @curve: elliptic curve domain parameters
  127. * @pk: public key as a point
  128. *
  129. * Valdiate public key according to SP800-56A section 5.6.2.3.3 ECC Full
  130. * Public-Key Validation Routine.
  131. *
  132. * Return: 0 if validation is successful, -EINVAL if validation is failed.
  133. */
  134. int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
  135. struct ecc_point *pk);
  136. /**
  137. * vli_is_zero() - Determine is vli is zero
  138. *
  139. * @vli: vli to check.
  140. * @ndigits: length of the @vli
  141. */
  142. bool vli_is_zero(const u64 *vli, unsigned int ndigits);
  143. /**
  144. * vli_cmp() - compare left and right vlis
  145. *
  146. * @left: vli
  147. * @right: vli
  148. * @ndigits: length of both vlis
  149. *
  150. * Returns sign of @left - @right, i.e. -1 if @left < @right,
  151. * 0 if @left == @right, 1 if @left > @right.
  152. */
  153. int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits);
  154. /**
  155. * vli_sub() - Subtracts right from left
  156. *
  157. * @result: where to write result
  158. * @left: vli
  159. * @right vli
  160. * @ndigits: length of all vlis
  161. *
  162. * Note: can modify in-place.
  163. *
  164. * Return: carry bit.
  165. */
  166. u64 vli_sub(u64 *result, const u64 *left, const u64 *right,
  167. unsigned int ndigits);
  168. /**
  169. * vli_from_be64() - Load vli from big-endian u64 array
  170. *
  171. * @dest: destination vli
  172. * @src: source array of u64 BE values
  173. * @ndigits: length of both vli and array
  174. */
  175. void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits);
  176. /**
  177. * vli_from_le64() - Load vli from little-endian u64 array
  178. *
  179. * @dest: destination vli
  180. * @src: source array of u64 LE values
  181. * @ndigits: length of both vli and array
  182. */
  183. void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits);
  184. /**
  185. * vli_mod_inv() - Modular inversion
  186. *
  187. * @result: where to write vli number
  188. * @input: vli value to operate on
  189. * @mod: modulus
  190. * @ndigits: length of all vlis
  191. */
  192. void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod,
  193. unsigned int ndigits);
  194. /**
  195. * vli_mod_mult_slow() - Modular multiplication
  196. *
  197. * @result: where to write result value
  198. * @left: vli number to multiply with @right
  199. * @right: vli number to multiply with @left
  200. * @mod: modulus
  201. * @ndigits: length of all vlis
  202. *
  203. * Note: Assumes that mod is big enough curve order.
  204. */
  205. void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right,
  206. const u64 *mod, unsigned int ndigits);
  207. /**
  208. * vli_num_bits() - Counts the number of bits required for vli.
  209. *
  210. * @vli: vli to check.
  211. * @ndigits: Length of the @vli
  212. *
  213. * Return: The number of bits required to represent @vli.
  214. */
  215. unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits);
  216. /**
  217. * ecc_aloc_point() - Allocate ECC point.
  218. *
  219. * @ndigits: Length of vlis in u64 qwords.
  220. *
  221. * Return: Pointer to the allocated point or NULL if allocation failed.
  222. */
  223. struct ecc_point *ecc_alloc_point(unsigned int ndigits);
  224. /**
  225. * ecc_free_point() - Free ECC point.
  226. *
  227. * @p: The point to free.
  228. */
  229. void ecc_free_point(struct ecc_point *p);
  230. /**
  231. * ecc_point_is_zero() - Check if point is zero.
  232. *
  233. * @p: Point to check for zero.
  234. *
  235. * Return: true if point is the point at infinity, false otherwise.
  236. */
  237. bool ecc_point_is_zero(const struct ecc_point *point);
  238. /**
  239. * ecc_point_mult_shamir() - Add two points multiplied by scalars
  240. *
  241. * @result: resulting point
  242. * @x: scalar to multiply with @p
  243. * @p: point to multiply with @x
  244. * @y: scalar to multiply with @q
  245. * @q: point to multiply with @y
  246. * @curve: curve
  247. *
  248. * Returns result = x * p + x * q over the curve.
  249. * This works faster than two multiplications and addition.
  250. */
  251. void ecc_point_mult_shamir(const struct ecc_point *result,
  252. const u64 *x, const struct ecc_point *p,
  253. const u64 *y, const struct ecc_point *q,
  254. const struct ecc_curve *curve);
  255. #endif