ecdh_helper.c 2.1 KB

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485
  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * Copyright (c) 2016, Intel Corporation
  4. * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
  5. */
  6. #include <linux/kernel.h>
  7. #include <linux/export.h>
  8. #include <linux/err.h>
  9. #include <linux/string.h>
  10. #include <crypto/ecdh.h>
  11. #include <crypto/kpp.h>
  12. #define ECDH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 2 * sizeof(short))
  13. static inline u8 *ecdh_pack_data(void *dst, const void *src, size_t sz)
  14. {
  15. memcpy(dst, src, sz);
  16. return dst + sz;
  17. }
  18. static inline const u8 *ecdh_unpack_data(void *dst, const void *src, size_t sz)
  19. {
  20. memcpy(dst, src, sz);
  21. return src + sz;
  22. }
  23. unsigned int crypto_ecdh_key_len(const struct ecdh *params)
  24. {
  25. return ECDH_KPP_SECRET_MIN_SIZE + params->key_size;
  26. }
  27. EXPORT_SYMBOL_GPL(crypto_ecdh_key_len);
  28. int crypto_ecdh_encode_key(char *buf, unsigned int len,
  29. const struct ecdh *params)
  30. {
  31. u8 *ptr = buf;
  32. struct kpp_secret secret = {
  33. .type = CRYPTO_KPP_SECRET_TYPE_ECDH,
  34. .len = len
  35. };
  36. if (unlikely(!buf))
  37. return -EINVAL;
  38. if (len != crypto_ecdh_key_len(params))
  39. return -EINVAL;
  40. ptr = ecdh_pack_data(ptr, &secret, sizeof(secret));
  41. ptr = ecdh_pack_data(ptr, &params->curve_id, sizeof(params->curve_id));
  42. ptr = ecdh_pack_data(ptr, &params->key_size, sizeof(params->key_size));
  43. ecdh_pack_data(ptr, params->key, params->key_size);
  44. return 0;
  45. }
  46. EXPORT_SYMBOL_GPL(crypto_ecdh_encode_key);
  47. int crypto_ecdh_decode_key(const char *buf, unsigned int len,
  48. struct ecdh *params)
  49. {
  50. const u8 *ptr = buf;
  51. struct kpp_secret secret;
  52. if (unlikely(!buf || len < ECDH_KPP_SECRET_MIN_SIZE))
  53. return -EINVAL;
  54. ptr = ecdh_unpack_data(&secret, ptr, sizeof(secret));
  55. if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
  56. return -EINVAL;
  57. if (unlikely(len < secret.len))
  58. return -EINVAL;
  59. ptr = ecdh_unpack_data(&params->curve_id, ptr, sizeof(params->curve_id));
  60. ptr = ecdh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
  61. if (secret.len != crypto_ecdh_key_len(params))
  62. return -EINVAL;
  63. /* Don't allocate memory. Set pointer to data
  64. * within the given buffer
  65. */
  66. params->key = (void *)ptr;
  67. return 0;
  68. }
  69. EXPORT_SYMBOL_GPL(crypto_ecdh_decode_key);