crypto/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 #define ECC_MAX_DIGITS  4 /* 256 */
  30
  31 #define ECC_DIGITS_TO_BYTES_SHIFT 3
  32
  33 /**
  34  * ecc_is_key_valid() - Validate a given ECDH private key
  35  *
  36  * @curve_id:           id representing the curve to use
  37  * @ndigits:            curve number of digits
  38  * @private_key:        private key to be used for the given curve
  39  * @private_key_len:    private key len
  40  *
  41  * Returns 0 if the key is acceptable, a negative value otherwise
  42  */
  43 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
  44                      const u8 *private_key, unsigned int private_key_len);
  45
  46 /**
  47  * ecdh_make_pub_key() - Compute an ECC public key
  48  *
  49  * @curve_id:           id representing the curve to use
  50  * @private_key:        pregenerated private key for the given curve
  51  * @private_key_len:    length of private_key
  52  * @public_key:         buffer for storing the public key generated
  53  * @public_key_len:     length of the public_key buffer
  54  *
  55  * Returns 0 if the public key was generated successfully, a negative value
  56  * if an error occurred.
  57  */
  58 int ecdh_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
  59                       const u8 *private_key, unsigned int private_key_len,
  60                       u8 *public_key, unsigned int public_key_len);
  61
  62 /**
  63  * crypto_ecdh_shared_secret() - Compute a shared secret
  64  *
  65  * @curve_id:           id representing the curve to use
  66  * @private_key:        private key of part A
  67  * @private_key_len:    length of private_key
  68  * @public_key:         public key of counterpart B
  69  * @public_key_len:     length of public_key
  70  * @secret:             buffer for storing the calculated shared secret
  71  * @secret_len:         length of the secret buffer
  72  *
  73  * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
  74  * before using it for symmetric encryption or HMAC.
  75  *
  76  * Returns 0 if the shared secret was generated successfully, a negative value
  77  * if an error occurred.
  78  */
  79 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
  80                        const u8 *private_key, unsigned int private_key_len,
  81                        const u8 *public_key, unsigned int public_key_len,
  82                        u8 *secret, unsigned int secret_len);
  83 #endif