aboutsummaryrefslogtreecommitdiff
path: root/include/olm/crypto.h
blob: 9fc384212c212f51256b03ab623486a8e8a0943b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
/* Copyright 2015 OpenMarket Ltd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* C-compatible crpyto utility functions. At some point all of crypto.hh will
 * move here.
 */

#ifndef OLM_CRYPTO_H_
#define OLM_CRYPTO_H_

#include <stdint.h>
#include <stdlib.h>

#ifdef __cplusplus
extern "C" {
#endif

/** length of a sha256 hash */
#define SHA256_OUTPUT_LENGTH 32

/** length of a public or private Curve25519 key */
#define CURVE25519_KEY_LENGTH 32

/** length of the shared secret created by a Curve25519 ECDH operation */
#define CURVE25519_SHARED_SECRET_LENGTH 32

/** amount of random data required to create a Curve25519 keypair */
#define CURVE25519_RANDOM_LENGTH CURVE25519_KEY_LENGTH

/** length of a public Ed25519 key */
#define ED25519_PUBLIC_KEY_LENGTH 32

/** length of a private Ed25519 key */
#define ED25519_PRIVATE_KEY_LENGTH 64

/** amount of random data required to create a Ed25519 keypair */
#define ED25519_RANDOM_LENGTH 32

/** length of an Ed25519 signature */
#define ED25519_SIGNATURE_LENGTH 64

/** length of an aes256 key */
#define AES256_KEY_LENGTH 32

/** length of an aes256 initialisation vector */
#define AES256_IV_LENGTH 16

struct _olm_curve25519_public_key {
    uint8_t public_key[CURVE25519_KEY_LENGTH];
};

struct _olm_curve25519_private_key {
    uint8_t private_key[CURVE25519_KEY_LENGTH];
};

struct _olm_curve25519_key_pair {
    struct _olm_curve25519_public_key public_key;
    struct _olm_curve25519_private_key private_key;
};

struct _olm_ed25519_public_key {
    uint8_t public_key[ED25519_PUBLIC_KEY_LENGTH];
};

struct _olm_ed25519_private_key {
    uint8_t private_key[ED25519_PRIVATE_KEY_LENGTH];
};

struct _olm_ed25519_key_pair {
    struct _olm_ed25519_public_key public_key;
    struct _olm_ed25519_private_key private_key;
};


/** Computes SHA-256 of the input. The output buffer must be a least
 * SHA256_OUTPUT_LENGTH (32) bytes long. */
void _olm_crypto_sha256(
    uint8_t const * input, size_t input_length,
    uint8_t * output
);

/** HMAC: Keyed-Hashing for Message Authentication
 * http://tools.ietf.org/html/rfc2104
 * Computes HMAC-SHA-256 of the input for the key. The output buffer must
 * be at least SHA256_OUTPUT_LENGTH (32) bytes long. */
void _olm_crypto_hmac_sha256(
    uint8_t const * key, size_t key_length,
    uint8_t const * input, size_t input_length,
    uint8_t * output
);


/** HMAC-based Key Derivation Function (HKDF)
 * https://tools.ietf.org/html/rfc5869
 * Derives key material from the input bytes. */
void _olm_crypto_hkdf_sha256(
    uint8_t const * input, size_t input_length,
    uint8_t const * info, size_t info_length,
    uint8_t const * salt, size_t salt_length,
    uint8_t * output, size_t output_length
);


/** Generate a curve25519 key pair
 * random_32_bytes should be CURVE25519_RANDOM_LENGTH (32) bytes long.
 */
void _olm_crypto_curve25519_generate_key(
    uint8_t const * random_32_bytes,
    struct _olm_curve25519_key_pair *output
);


/** Create a shared secret using our private key and their public key.
 * The output buffer must be at least CURVE25519_SHARED_SECRET_LENGTH (32) bytes long.
 */
void _olm_crypto_curve25519_shared_secret(
    const struct _olm_curve25519_key_pair *our_key,
    const struct _olm_curve25519_public_key *their_key,
    uint8_t * output
);

/** Generate an ed25519 key pair
 * random_32_bytes should be ED25519_RANDOM_LENGTH (32) bytes long.
 */
void _olm_crypto_ed25519_generate_key(
    uint8_t const * random_bytes,
    struct _olm_ed25519_key_pair *output
);

/** Signs the message using our private key.
 *
 * The output buffer must be at least ED25519_SIGNATURE_LENGTH (64) bytes
 * long. */
void _olm_crypto_ed25519_sign(
    const struct _olm_ed25519_key_pair *our_key,
    const uint8_t * message, size_t message_length,
    uint8_t * output
);

/** Verify an ed25519 signature
 * The signature input buffer must be ED25519_SIGNATURE_LENGTH (64) bytes long.
 * Returns non-zero if the signature is valid. */
int _olm_crypto_ed25519_verify(
    const struct _olm_ed25519_public_key *their_key,
    const uint8_t * message, size_t message_length,
    const uint8_t * signature
);



#ifdef __cplusplus
} // extern "C"
#endif

#endif /* OLM_CRYPTO_H_ */