]>
Commit | Line | Data |
---|---|---|
1308e022 MC |
1 | /* |
2 | * Copyright 2017 The OpenSSL Project Authors. All Rights Reserved. | |
3 | * Copyright 2015-2016 Cryptography Research, Inc. | |
7324473f | 4 | * |
1308e022 MC |
5 | * Licensed under the OpenSSL license (the "License"). You may not use |
6 | * this file except in compliance with the License. You can obtain a copy | |
7 | * in the file LICENSE in the source distribution or at | |
8 | * https://www.openssl.org/source/license.html | |
7324473f | 9 | * |
1308e022 | 10 | * Originally written by Mike Hamburg |
7324473f MC |
11 | */ |
12 | ||
aeeef83c MC |
13 | #ifndef __C448_ED448_H__ |
14 | # define __C448_ED448_H__ 1 | |
7324473f | 15 | |
205fd638 | 16 | # include "point_448.h" |
7324473f MC |
17 | |
18 | #ifdef __cplusplus | |
19 | extern "C" { | |
20 | #endif | |
21 | ||
8d55f844 | 22 | /* Number of bytes in an EdDSA public key. */ |
db90b274 | 23 | # define EDDSA_448_PUBLIC_BYTES 57 |
7324473f | 24 | |
8d55f844 | 25 | /* Number of bytes in an EdDSA private key. */ |
db90b274 | 26 | # define EDDSA_448_PRIVATE_BYTES EDDSA_448_PUBLIC_BYTES |
7324473f | 27 | |
8d55f844 | 28 | /* Number of bytes in an EdDSA private key. */ |
db90b274 MC |
29 | # define EDDSA_448_SIGNATURE_BYTES (EDDSA_448_PUBLIC_BYTES + \ |
30 | EDDSA_448_PRIVATE_BYTES) | |
7324473f | 31 | |
8d55f844 | 32 | /* EdDSA encoding ratio. */ |
db90b274 | 33 | # define C448_EDDSA_ENCODE_RATIO 4 |
7324473f | 34 | |
8d55f844 | 35 | /* EdDSA decoding ratio. */ |
db90b274 | 36 | # define C448_EDDSA_DECODE_RATIO (4 / 4) |
7324473f | 37 | |
8d55f844 MC |
38 | /* |
39 | * EdDSA key generation. This function uses a different (non-Decaf) encoding. | |
7324473f | 40 | * |
8d55f844 MC |
41 | * pubkey (out): The public key. |
42 | * privkey (in): The private key. | |
205fd638 | 43 | */ |
aeeef83c | 44 | c448_error_t c448_ed448_derive_public_key( |
db90b274 MC |
45 | uint8_t pubkey [EDDSA_448_PUBLIC_BYTES], |
46 | const uint8_t privkey [EDDSA_448_PRIVATE_BYTES]); | |
8d55f844 MC |
47 | |
48 | /* | |
49 | * EdDSA signing. | |
50 | * | |
51 | * signature (out): The signature. | |
52 | * privkey (in): The private key. | |
53 | * pubkey (in): The public key. | |
54 | * message (in): The message to sign. | |
55 | * message_len (in): The length of the message. | |
56 | * prehashed (in): Nonzero if the message is actually the hash of something | |
57 | * you want to sign. | |
58 | * context (in): A "context" for this signature of up to 255 bytes. | |
59 | * context_len (in): Length of the context. | |
60 | * | |
61 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
62 | * non-prehashed messages, at least without some very careful protocol-level | |
63 | * disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make | |
64 | * it harder to screw this up, but this C code gives you no seat belt. | |
205fd638 | 65 | */ |
aeeef83c | 66 | c448_error_t c448_ed448_sign( |
db90b274 MC |
67 | uint8_t signature[EDDSA_448_SIGNATURE_BYTES], |
68 | const uint8_t privkey[EDDSA_448_PRIVATE_BYTES], | |
69 | const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES], | |
8d55f844 MC |
70 | const uint8_t *message, size_t message_len, |
71 | uint8_t prehashed, const uint8_t *context, | |
72 | size_t context_len) | |
73 | __attribute__ ((nonnull(1, 2, 3))); | |
74 | ||
75 | /* | |
76 | * EdDSA signing with prehash. | |
77 | * | |
78 | * signature (out): The signature. | |
79 | * privkey (in): The private key. | |
80 | * pubkey (in): The public key. | |
81 | * hash (in): The hash of the message. This object will not be modified by the | |
82 | * call. | |
83 | * context (in): A "context" for this signature of up to 255 bytes. Must be the | |
84 | * same as what was used for the prehash. | |
85 | * context_len (in): Length of the context. | |
86 | * | |
87 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
88 | * non-prehashed messages, at least without some very careful protocol-level | |
89 | * disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make | |
90 | * it harder to screw this up, but this C code gives you no seat belt. | |
205fd638 | 91 | */ |
aeeef83c | 92 | c448_error_t c448_ed448_sign_prehash( |
db90b274 MC |
93 | uint8_t signature[EDDSA_448_SIGNATURE_BYTES], |
94 | const uint8_t privkey[EDDSA_448_PRIVATE_BYTES], | |
95 | const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES], | |
8d55f844 MC |
96 | const uint8_t hash[64], |
97 | const uint8_t *context, | |
98 | size_t context_len) | |
99 | __attribute__ ((nonnull(1, 2, 3, 4))); | |
100 | ||
101 | /* | |
102 | * EdDSA signature verification. | |
7324473f MC |
103 | * |
104 | * Uses the standard (i.e. less-strict) verification formula. | |
105 | * | |
8d55f844 MC |
106 | * signature (in): The signature. |
107 | * pubkey (in): The public key. | |
108 | * message (in): The message to verify. | |
109 | * message_len (in): The length of the message. | |
110 | * prehashed (in): Nonzero if the message is actually the hash of something you | |
111 | * want to verify. | |
112 | * context (in): A "context" for this signature of up to 255 bytes. | |
113 | * context_len (in): Length of the context. | |
114 | * | |
115 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
116 | * non-prehashed messages, at least without some very careful protocol-level | |
117 | * disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make | |
118 | * it harder to screw this up, but this C code gives you no seat belt. | |
7324473f | 119 | */ |
aeeef83c | 120 | c448_error_t c448_ed448_verify(const uint8_t |
db90b274 | 121 | signature[EDDSA_448_SIGNATURE_BYTES], |
205fd638 | 122 | const uint8_t |
db90b274 | 123 | pubkey[EDDSA_448_PUBLIC_BYTES], |
205fd638 MC |
124 | const uint8_t *message, size_t message_len, |
125 | uint8_t prehashed, const uint8_t *context, | |
126 | uint8_t context_len) | |
8d55f844 | 127 | __attribute__ ((nonnull(1, 2))); |
7324473f | 128 | |
8d55f844 MC |
129 | /* |
130 | * EdDSA signature verification. | |
7324473f MC |
131 | * |
132 | * Uses the standard (i.e. less-strict) verification formula. | |
133 | * | |
8d55f844 MC |
134 | * signature (in): The signature. |
135 | * pubkey (in): The public key. | |
136 | * hash (in): The hash of the message. This object will not be modified by the | |
137 | * call. | |
138 | * context (in): A "context" for this signature of up to 255 bytes. Must be the | |
139 | * same as what was used for the prehash. | |
140 | * context_len (in): Length of the context. | |
141 | * | |
142 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
143 | * non-prehashed messages, at least without some very careful protocol-level | |
144 | * disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make | |
145 | * it harder to screw this up, but this C code gives you no seat belt. | |
7324473f | 146 | */ |
aeeef83c | 147 | c448_error_t c448_ed448_verify_prehash( |
db90b274 MC |
148 | const uint8_t signature[EDDSA_448_SIGNATURE_BYTES], |
149 | const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES], | |
8d55f844 MC |
150 | const uint8_t hash[64], |
151 | const uint8_t *context, | |
152 | uint8_t context_len) | |
153 | __attribute__ ((nonnull(1, 2))); | |
154 | ||
155 | /* | |
156 | * EdDSA point encoding. Used internally, exposed externally. | |
db90b274 | 157 | * Multiplies by C448_EDDSA_ENCODE_RATIO first. |
7324473f MC |
158 | * |
159 | * The multiplication is required because the EdDSA encoding represents | |
160 | * the cofactor information, but the Decaf encoding ignores it (which | |
161 | * is the whole point). So if you decode from EdDSA and re-encode to | |
162 | * EdDSA, the cofactor info must get cleared, because the intermediate | |
163 | * representation doesn't track it. | |
164 | * | |
db90b274 MC |
165 | * The way we handle this is to multiply by C448_EDDSA_DECODE_RATIO when |
166 | * decoding, and by C448_EDDSA_ENCODE_RATIO when encoding. The product of | |
aeeef83c MC |
167 | * these ratios is always exactly the cofactor 4, so the cofactor ends up |
168 | * cleared one way or another. But exactly how that shakes out depends on the | |
169 | * base points specified in RFC 8032. | |
7324473f MC |
170 | * |
171 | * The upshot is that if you pass the Decaf/Ristretto base point to | |
db90b274 | 172 | * this function, you will get C448_EDDSA_ENCODE_RATIO times the |
7324473f MC |
173 | * EdDSA base point. |
174 | * | |
8d55f844 MC |
175 | * enc (out): The encoded point. |
176 | * p (in): The point. | |
205fd638 | 177 | */ |
8d55f844 | 178 | void curve448_point_mul_by_ratio_and_encode_like_eddsa( |
db90b274 | 179 | uint8_t enc [EDDSA_448_PUBLIC_BYTES], |
8d55f844 | 180 | const curve448_point_t p); |
7324473f | 181 | |
8d55f844 | 182 | /* |
db90b274 | 183 | * EdDSA point decoding. Multiplies by C448_EDDSA_DECODE_RATIO, and |
8d55f844 | 184 | * ignores cofactor information. |
7324473f | 185 | * |
e7772577 | 186 | * See notes on curve448_point_mul_by_ratio_and_encode_like_eddsa |
7324473f | 187 | * |
8d55f844 MC |
188 | * enc (out): The encoded point. |
189 | * p (in): The point. | |
205fd638 | 190 | */ |
aeeef83c | 191 | c448_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio( |
8d55f844 | 192 | curve448_point_t p, |
db90b274 | 193 | const uint8_t enc[EDDSA_448_PUBLIC_BYTES]); |
8d55f844 | 194 | |
8d55f844 MC |
195 | /* |
196 | * EdDSA to ECDH private key conversion | |
7324473f MC |
197 | * Using the appropriate hash function, hash the EdDSA private key |
198 | * and keep only the lower bytes to get the ECDH private key | |
199 | * | |
8d55f844 MC |
200 | * x (out): The ECDH private key as in RFC7748 |
201 | * ed (in): The EdDSA private key | |
7324473f | 202 | */ |
aeeef83c | 203 | c448_error_t c448_ed448_convert_private_key_to_x448( |
db90b274 MC |
204 | uint8_t x[X448_PRIVATE_BYTES], |
205 | const uint8_t ed[EDDSA_448_PRIVATE_BYTES]); | |
7324473f MC |
206 | |
207 | #ifdef __cplusplus | |
208 | } /* extern "C" */ | |
209 | #endif | |
210 | ||
aeeef83c | 211 | #endif /* __C448_ED448_H__ */ |