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
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
/*
* Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 2015-2016 Cryptography Research, Inc.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*
* Originally written by Mike Hamburg
*/
#ifndef HEADER_ED448_H
# define HEADER_ED448_H
# include "point_448.h"
/* Number of bytes in an EdDSA public key. */
# define EDDSA_448_PUBLIC_BYTES 57
/* Number of bytes in an EdDSA private key. */
# define EDDSA_448_PRIVATE_BYTES EDDSA_448_PUBLIC_BYTES
/* Number of bytes in an EdDSA private key. */
# define EDDSA_448_SIGNATURE_BYTES (EDDSA_448_PUBLIC_BYTES + \
EDDSA_448_PRIVATE_BYTES)
/* EdDSA encoding ratio. */
# define C448_EDDSA_ENCODE_RATIO 4
/* EdDSA decoding ratio. */
# define C448_EDDSA_DECODE_RATIO (4 / 4)
/*
* EdDSA key generation. This function uses a different (non-Decaf) encoding.
*
* pubkey (out): The public key.
* privkey (in): The private key.
*/
c448_error_t c448_ed448_derive_public_key(
uint8_t pubkey [EDDSA_448_PUBLIC_BYTES],
const uint8_t privkey [EDDSA_448_PRIVATE_BYTES]);
/*
* EdDSA signing.
*
* signature (out): The signature.
* privkey (in): The private key.
* pubkey (in): The public key.
* message (in): The message to sign.
* message_len (in): The length of the message.
* prehashed (in): Nonzero if the message is actually the hash of something
* you want to sign.
* context (in): A "context" for this signature of up to 255 bytes.
* context_len (in): Length of the context.
*
* For Ed25519, it is unsafe to use the same key for both prehashed and
* non-prehashed messages, at least without some very careful protocol-level
* disambiguation. For Ed448 it is safe.
*/
c448_error_t c448_ed448_sign(
uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
const uint8_t *message, size_t message_len,
uint8_t prehashed, const uint8_t *context,
size_t context_len);
/*
* EdDSA signing with prehash.
*
* signature (out): The signature.
* privkey (in): The private key.
* pubkey (in): The public key.
* hash (in): The hash of the message. This object will not be modified by the
* call.
* context (in): A "context" for this signature of up to 255 bytes. Must be the
* same as what was used for the prehash.
* context_len (in): Length of the context.
*
* For Ed25519, it is unsafe to use the same key for both prehashed and
* non-prehashed messages, at least without some very careful protocol-level
* disambiguation. For Ed448 it is safe.
*/
c448_error_t c448_ed448_sign_prehash(
uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
const uint8_t hash[64],
const uint8_t *context,
size_t context_len);
/*
* EdDSA signature verification.
*
* Uses the standard (i.e. less-strict) verification formula.
*
* signature (in): The signature.
* pubkey (in): The public key.
* message (in): The message to verify.
* message_len (in): The length of the message.
* prehashed (in): Nonzero if the message is actually the hash of something you
* want to verify.
* context (in): A "context" for this signature of up to 255 bytes.
* context_len (in): Length of the context.
*
* For Ed25519, it is unsafe to use the same key for both prehashed and
* non-prehashed messages, at least without some very careful protocol-level
* disambiguation. For Ed448 it is safe.
*/
c448_error_t c448_ed448_verify(const uint8_t
signature[EDDSA_448_SIGNATURE_BYTES],
const uint8_t
pubkey[EDDSA_448_PUBLIC_BYTES],
const uint8_t *message, size_t message_len,
uint8_t prehashed, const uint8_t *context,
uint8_t context_len);
/*
* EdDSA signature verification.
*
* Uses the standard (i.e. less-strict) verification formula.
*
* signature (in): The signature.
* pubkey (in): The public key.
* hash (in): The hash of the message. This object will not be modified by the
* call.
* context (in): A "context" for this signature of up to 255 bytes. Must be the
* same as what was used for the prehash.
* context_len (in): Length of the context.
*
* For Ed25519, it is unsafe to use the same key for both prehashed and
* non-prehashed messages, at least without some very careful protocol-level
* disambiguation. For Ed448 it is safe.
*/
c448_error_t c448_ed448_verify_prehash(
const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
const uint8_t hash[64],
const uint8_t *context,
uint8_t context_len);
/*
* EdDSA point encoding. Used internally, exposed externally.
* Multiplies by C448_EDDSA_ENCODE_RATIO first.
*
* The multiplication is required because the EdDSA encoding represents
* the cofactor information, but the Decaf encoding ignores it (which
* is the whole point). So if you decode from EdDSA and re-encode to
* EdDSA, the cofactor info must get cleared, because the intermediate
* representation doesn't track it.
*
* The way we handle this is to multiply by C448_EDDSA_DECODE_RATIO when
* decoding, and by C448_EDDSA_ENCODE_RATIO when encoding. The product of
* these ratios is always exactly the cofactor 4, so the cofactor ends up
* cleared one way or another. But exactly how that shakes out depends on the
* base points specified in RFC 8032.
*
* The upshot is that if you pass the Decaf/Ristretto base point to
* this function, you will get C448_EDDSA_ENCODE_RATIO times the
* EdDSA base point.
*
* enc (out): The encoded point.
* p (in): The point.
*/
void curve448_point_mul_by_ratio_and_encode_like_eddsa(
uint8_t enc [EDDSA_448_PUBLIC_BYTES],
const curve448_point_t p);
/*
* EdDSA point decoding. Multiplies by C448_EDDSA_DECODE_RATIO, and
* ignores cofactor information.
*
* See notes on curve448_point_mul_by_ratio_and_encode_like_eddsa
*
* enc (out): The encoded point.
* p (in): The point.
*/
c448_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio(
curve448_point_t p,
const uint8_t enc[EDDSA_448_PUBLIC_BYTES]);
/*
* EdDSA to ECDH private key conversion
* Using the appropriate hash function, hash the EdDSA private key
* and keep only the lower bytes to get the ECDH private key
*
* x (out): The ECDH private key as in RFC7748
* ed (in): The EdDSA private key
*/
c448_error_t c448_ed448_convert_private_key_to_x448(
uint8_t x[X448_PRIVATE_BYTES],
const uint8_t ed[EDDSA_448_PRIVATE_BYTES]);
#endif /* HEADER_ED448_H */
|
