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1308e022 | 1 | /* |
f53c7764 | 2 | * Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved. |
1308e022 | 3 | * Copyright 2015-2016 Cryptography Research, Inc. |
7324473f | 4 | * |
a7f182b7 | 5 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
1308e022 MC |
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 | ||
ae4186b0 DMSP |
13 | #ifndef OSSL_CRYPTO_EC_CURVE448_ED448_H |
14 | # define OSSL_CRYPTO_EC_CURVE448_ED448_H | |
7324473f | 15 | |
205fd638 | 16 | # include "point_448.h" |
7324473f | 17 | |
8d55f844 | 18 | /* Number of bytes in an EdDSA public key. */ |
db90b274 | 19 | # define EDDSA_448_PUBLIC_BYTES 57 |
7324473f | 20 | |
8d55f844 | 21 | /* Number of bytes in an EdDSA private key. */ |
db90b274 | 22 | # define EDDSA_448_PRIVATE_BYTES EDDSA_448_PUBLIC_BYTES |
7324473f | 23 | |
8d55f844 | 24 | /* Number of bytes in an EdDSA private key. */ |
db90b274 MC |
25 | # define EDDSA_448_SIGNATURE_BYTES (EDDSA_448_PUBLIC_BYTES + \ |
26 | EDDSA_448_PRIVATE_BYTES) | |
7324473f | 27 | |
8d55f844 | 28 | /* EdDSA encoding ratio. */ |
db90b274 | 29 | # define C448_EDDSA_ENCODE_RATIO 4 |
7324473f | 30 | |
8d55f844 | 31 | /* EdDSA decoding ratio. */ |
db90b274 | 32 | # define C448_EDDSA_DECODE_RATIO (4 / 4) |
7324473f | 33 | |
8d55f844 MC |
34 | /* |
35 | * EdDSA key generation. This function uses a different (non-Decaf) encoding. | |
7324473f | 36 | * |
8d55f844 MC |
37 | * pubkey (out): The public key. |
38 | * privkey (in): The private key. | |
205fd638 | 39 | */ |
aeeef83c | 40 | c448_error_t c448_ed448_derive_public_key( |
a9612d6c | 41 | OPENSSL_CTX *ctx, |
db90b274 MC |
42 | uint8_t pubkey [EDDSA_448_PUBLIC_BYTES], |
43 | const uint8_t privkey [EDDSA_448_PRIVATE_BYTES]); | |
8d55f844 MC |
44 | |
45 | /* | |
46 | * EdDSA signing. | |
47 | * | |
48 | * signature (out): The signature. | |
49 | * privkey (in): The private key. | |
50 | * pubkey (in): The public key. | |
51 | * message (in): The message to sign. | |
52 | * message_len (in): The length of the message. | |
53 | * prehashed (in): Nonzero if the message is actually the hash of something | |
54 | * you want to sign. | |
55 | * context (in): A "context" for this signature of up to 255 bytes. | |
56 | * context_len (in): Length of the context. | |
57 | * | |
58 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
59 | * non-prehashed messages, at least without some very careful protocol-level | |
53ef3252 | 60 | * disambiguation. For Ed448 it is safe. |
205fd638 | 61 | */ |
aeeef83c | 62 | c448_error_t c448_ed448_sign( |
a9612d6c | 63 | OPENSSL_CTX *ctx, |
db90b274 MC |
64 | uint8_t signature[EDDSA_448_SIGNATURE_BYTES], |
65 | const uint8_t privkey[EDDSA_448_PRIVATE_BYTES], | |
66 | const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES], | |
8d55f844 MC |
67 | const uint8_t *message, size_t message_len, |
68 | uint8_t prehashed, const uint8_t *context, | |
575d5afc | 69 | size_t context_len); |
8d55f844 MC |
70 | |
71 | /* | |
72 | * EdDSA signing with prehash. | |
73 | * | |
74 | * signature (out): The signature. | |
75 | * privkey (in): The private key. | |
76 | * pubkey (in): The public key. | |
77 | * hash (in): The hash of the message. This object will not be modified by the | |
78 | * call. | |
79 | * context (in): A "context" for this signature of up to 255 bytes. Must be the | |
80 | * same as what was used for the prehash. | |
81 | * context_len (in): Length of the context. | |
82 | * | |
83 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
84 | * non-prehashed messages, at least without some very careful protocol-level | |
53ef3252 | 85 | * disambiguation. For Ed448 it is safe. |
205fd638 | 86 | */ |
aeeef83c | 87 | c448_error_t c448_ed448_sign_prehash( |
a9612d6c | 88 | OPENSSL_CTX *ctx, |
db90b274 MC |
89 | uint8_t signature[EDDSA_448_SIGNATURE_BYTES], |
90 | const uint8_t privkey[EDDSA_448_PRIVATE_BYTES], | |
91 | const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES], | |
8d55f844 MC |
92 | const uint8_t hash[64], |
93 | const uint8_t *context, | |
575d5afc | 94 | size_t context_len); |
8d55f844 MC |
95 | |
96 | /* | |
97 | * EdDSA signature verification. | |
7324473f MC |
98 | * |
99 | * Uses the standard (i.e. less-strict) verification formula. | |
100 | * | |
8d55f844 MC |
101 | * signature (in): The signature. |
102 | * pubkey (in): The public key. | |
103 | * message (in): The message to verify. | |
104 | * message_len (in): The length of the message. | |
105 | * prehashed (in): Nonzero if the message is actually the hash of something you | |
106 | * want to verify. | |
107 | * context (in): A "context" for this signature of up to 255 bytes. | |
108 | * context_len (in): Length of the context. | |
109 | * | |
110 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
111 | * non-prehashed messages, at least without some very careful protocol-level | |
68b20c00 | 112 | * disambiguation. For Ed448 it is safe. |
7324473f | 113 | */ |
a9612d6c MC |
114 | c448_error_t c448_ed448_verify(OPENSSL_CTX *ctx, |
115 | const uint8_t | |
116 | signature[EDDSA_448_SIGNATURE_BYTES], | |
117 | const uint8_t | |
118 | pubkey[EDDSA_448_PUBLIC_BYTES], | |
119 | const uint8_t *message, size_t message_len, | |
120 | uint8_t prehashed, const uint8_t *context, | |
121 | uint8_t context_len); | |
7324473f | 122 | |
8d55f844 MC |
123 | /* |
124 | * EdDSA signature verification. | |
7324473f MC |
125 | * |
126 | * Uses the standard (i.e. less-strict) verification formula. | |
127 | * | |
8d55f844 MC |
128 | * signature (in): The signature. |
129 | * pubkey (in): The public key. | |
130 | * hash (in): The hash of the message. This object will not be modified by the | |
131 | * call. | |
132 | * context (in): A "context" for this signature of up to 255 bytes. Must be the | |
133 | * same as what was used for the prehash. | |
134 | * context_len (in): Length of the context. | |
135 | * | |
136 | * For Ed25519, it is unsafe to use the same key for both prehashed and | |
137 | * non-prehashed messages, at least without some very careful protocol-level | |
53ef3252 | 138 | * disambiguation. For Ed448 it is safe. |
7324473f | 139 | */ |
aeeef83c | 140 | c448_error_t c448_ed448_verify_prehash( |
a9612d6c | 141 | OPENSSL_CTX *ctx, |
db90b274 MC |
142 | const uint8_t signature[EDDSA_448_SIGNATURE_BYTES], |
143 | const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES], | |
8d55f844 MC |
144 | const uint8_t hash[64], |
145 | const uint8_t *context, | |
575d5afc | 146 | uint8_t context_len); |
8d55f844 MC |
147 | |
148 | /* | |
149 | * EdDSA point encoding. Used internally, exposed externally. | |
db90b274 | 150 | * Multiplies by C448_EDDSA_ENCODE_RATIO first. |
7324473f MC |
151 | * |
152 | * The multiplication is required because the EdDSA encoding represents | |
153 | * the cofactor information, but the Decaf encoding ignores it (which | |
154 | * is the whole point). So if you decode from EdDSA and re-encode to | |
155 | * EdDSA, the cofactor info must get cleared, because the intermediate | |
156 | * representation doesn't track it. | |
157 | * | |
db90b274 MC |
158 | * The way we handle this is to multiply by C448_EDDSA_DECODE_RATIO when |
159 | * decoding, and by C448_EDDSA_ENCODE_RATIO when encoding. The product of | |
aeeef83c MC |
160 | * these ratios is always exactly the cofactor 4, so the cofactor ends up |
161 | * cleared one way or another. But exactly how that shakes out depends on the | |
162 | * base points specified in RFC 8032. | |
7324473f MC |
163 | * |
164 | * The upshot is that if you pass the Decaf/Ristretto base point to | |
db90b274 | 165 | * this function, you will get C448_EDDSA_ENCODE_RATIO times the |
7324473f MC |
166 | * EdDSA base point. |
167 | * | |
8d55f844 MC |
168 | * enc (out): The encoded point. |
169 | * p (in): The point. | |
205fd638 | 170 | */ |
8d55f844 | 171 | void curve448_point_mul_by_ratio_and_encode_like_eddsa( |
db90b274 | 172 | uint8_t enc [EDDSA_448_PUBLIC_BYTES], |
8d55f844 | 173 | const curve448_point_t p); |
7324473f | 174 | |
8d55f844 | 175 | /* |
db90b274 | 176 | * EdDSA point decoding. Multiplies by C448_EDDSA_DECODE_RATIO, and |
8d55f844 | 177 | * ignores cofactor information. |
7324473f | 178 | * |
e7772577 | 179 | * See notes on curve448_point_mul_by_ratio_and_encode_like_eddsa |
7324473f | 180 | * |
8d55f844 MC |
181 | * enc (out): The encoded point. |
182 | * p (in): The point. | |
205fd638 | 183 | */ |
aeeef83c | 184 | c448_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio( |
8d55f844 | 185 | curve448_point_t p, |
db90b274 | 186 | const uint8_t enc[EDDSA_448_PUBLIC_BYTES]); |
8d55f844 | 187 | |
8d55f844 MC |
188 | /* |
189 | * EdDSA to ECDH private key conversion | |
7324473f MC |
190 | * Using the appropriate hash function, hash the EdDSA private key |
191 | * and keep only the lower bytes to get the ECDH private key | |
192 | * | |
8d55f844 MC |
193 | * x (out): The ECDH private key as in RFC7748 |
194 | * ed (in): The EdDSA private key | |
7324473f | 195 | */ |
aeeef83c | 196 | c448_error_t c448_ed448_convert_private_key_to_x448( |
a9612d6c | 197 | OPENSSL_CTX *ctx, |
db90b274 MC |
198 | uint8_t x[X448_PRIVATE_BYTES], |
199 | const uint8_t ed[EDDSA_448_PRIVATE_BYTES]); | |
7324473f | 200 | |
ae4186b0 | 201 | #endif /* OSSL_CRYPTO_EC_CURVE448_ED448_H */ |