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_CURVE_NIST_P192_DIGITS  3
30 #define ECC_CURVE_NIST_P256_DIGITS  4
31 #define ECC_MAX_DIGITS              ECC_CURVE_NIST_P256_DIGITS
32 
33 #define ECC_DIGITS_TO_BYTES_SHIFT 3
34 
35 /**
36  * ecc_is_key_valid() - Validate a given ECDH private key
37  *
38  * @curve_id:		id representing the curve to use
39  * @ndigits:		curve's number of digits
40  * @private_key:	private key to be used for the given curve
41  * @private_key_len:	private key length
42  *
43  * Returns 0 if the key is acceptable, a negative value otherwise
44  */
45 int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
46 		     const u64 *private_key, unsigned int private_key_len);
47 
48 /**
49  * ecc_gen_privkey() -  Generates an ECC private key.
50  * The private key is a random integer in the range 0 < random < n, where n is a
51  * prime that is the order of the cyclic subgroup generated by the distinguished
52  * point G.
53  * @curve_id:		id representing the curve to use
54  * @ndigits:		curve number of digits
55  * @private_key:	buffer for storing the generated private key
56  *
57  * Returns 0 if the private key was generated successfully, a negative value
58  * if an error occurred.
59  */
60 int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
61 
62 /**
63  * ecc_make_pub_key() - Compute an ECC public key
64  *
65  * @curve_id:		id representing the curve to use
66  * @ndigits:		curve's number of digits
67  * @private_key:	pregenerated private key for the given curve
68  * @public_key:		buffer for storing the generated public key
69  *
70  * Returns 0 if the public key was generated successfully, a negative value
71  * if an error occurred.
72  */
73 int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
74 		     const u64 *private_key, u64 *public_key);
75 
76 /**
77  * crypto_ecdh_shared_secret() - Compute a shared secret
78  *
79  * @curve_id:		id representing the curve to use
80  * @ndigits:		curve's number of digits
81  * @private_key:	private key of part A
82  * @public_key:		public key of counterpart B
83  * @secret:		buffer for storing the calculated shared secret
84  *
85  * Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
86  * before using it for symmetric encryption or HMAC.
87  *
88  * Returns 0 if the shared secret was generated successfully, a negative value
89  * if an error occurred.
90  */
91 int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
92 			      const u64 *private_key, const u64 *public_key,
93 			      u64 *secret);
94 #endif
95