| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * The Ed25519 signature scheme |
| 4 | * |
| 5 | * (c) 2017 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 12 | * Catacomb is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU Library General Public License as |
| 14 | * published by the Free Software Foundation; either version 2 of the |
| 15 | * License, or (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with Catacomb; if not, write to the Free |
| 24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | #ifndef CATACOMB_ED25519_H |
| 29 | #define CATACOMB_ED25519_H |
| 30 | |
| 31 | #ifdef __cplusplus |
| 32 | extern "C" { |
| 33 | #endif |
| 34 | |
| 35 | /*----- Notes on the Ed25519 signature scheme -----------------------------* |
| 36 | * |
| 37 | * This is Ed25519, as described in Daniel J. Bernstein, Neils Duif, Tanja |
| 38 | * Lange, Peter Schwabe, and Bo-Yin Yang, `High-speed high-security |
| 39 | * signatures', CHES 2011, https://ed25519.cr.yp.to/ed25519-20110926.pdf |
| 40 | * |
| 41 | * Specifically, this code implements `PureEdDSA', according to the |
| 42 | * definition in Daniel J. Bernstein, Simon Josefsson, Tanja Lange, Peter |
| 43 | * Schwabe, and Bo-Yin Yang, `EdDSA for more curves', |
| 44 | * https://ed25519.cr.yp.to/eddsa-20150704.pdf. HashEdEDSA can be |
| 45 | * implemented easily by presenting a hash of a message to the functions |
| 46 | * here, as the message to be signed or verified. |
| 47 | * |
| 48 | * It also implements `Ed25519ctx' and `Ed25519ph' as described in RFC8032, |
| 49 | * though in the latter case it assumes that you've already done the hashing |
| 50 | * and have provided the hash as the `message' input. |
| 51 | */ |
| 52 | |
| 53 | /*----- Header files ------------------------------------------------------*/ |
| 54 | |
| 55 | #include <mLib/bits.h> |
| 56 | |
| 57 | #ifndef CATACOMB_KEY_H |
| 58 | # include "key.h" |
| 59 | #endif |
| 60 | |
| 61 | /*----- Important constants -----------------------------------------------*/ |
| 62 | |
| 63 | #define ED25519_KEYSZ 32u |
| 64 | #define ED25519_PUBSZ 32u |
| 65 | #define ED25519_SIGSZ 64u |
| 66 | |
| 67 | #define ED25519_MAXPERSOSZ 255u |
| 68 | |
| 69 | /*----- Key fetching ------------------------------------------------------*/ |
| 70 | |
| 71 | typedef struct ed25519_priv { key_bin priv, pub; } ed25519_priv; |
| 72 | typedef struct ed25519_pub { key_bin pub; } ed25519_pub; |
| 73 | |
| 74 | extern const key_fetchdef ed25519_pubfetch[], ed25519_privfetch[]; |
| 75 | #define ED25519_PUBFETCHSZ 3 |
| 76 | #define ED25519_PRIVFETCHSZ 6 |
| 77 | |
| 78 | /*----- Functions provided ------------------------------------------------*/ |
| 79 | |
| 80 | /* --- @ed25519_pubkey@ --- * |
| 81 | * |
| 82 | * Arguments: @octet K[ED25519_PUBSZ]@ = where to put the public key |
| 83 | * @const void *k@ = private key |
| 84 | * @size_t ksz@ = length of private key |
| 85 | * |
| 86 | * Returns: --- |
| 87 | * |
| 88 | * Use: Derives the public key from a private key. |
| 89 | */ |
| 90 | |
| 91 | extern void ed25519_pubkey(octet /*K*/[ED25519_PUBSZ], |
| 92 | const void */*k*/, size_t /*ksz*/); |
| 93 | |
| 94 | /* --- @ed25519_sign@, @ed25519ctx_sign@ --- * |
| 95 | * |
| 96 | * Arguments: @octet sig[ED25519_SIGSZ]@ = where to put the signature |
| 97 | * @const void *k@ = private key |
| 98 | * @size_t ksz@ = length of private key |
| 99 | * @const octet K[ED25519_PUBSZ]@ = public key |
| 100 | * @int phflag@ = whether the `message' has been hashed already |
| 101 | * @const void *p@ = personalization string |
| 102 | * @size_t psz@ = length of personalization string |
| 103 | * @const void *m@ = message to sign |
| 104 | * @size_t msz@ = length of message |
| 105 | * |
| 106 | * Returns: --- |
| 107 | * |
| 108 | * Use: Signs a message. |
| 109 | * |
| 110 | * In @ed25519ctx_sign@, if @phflag@ is @-1@ then you get plain |
| 111 | * old Ed25519: the personalization string pointer @p@ will be |
| 112 | * ignored. If @phflag > 0@ then the `message' @m@ should be a |
| 113 | * SHA512 hash of the actual message. |
| 114 | */ |
| 115 | |
| 116 | extern void ed25519ctx_sign(octet /*sig*/[ED25519_SIGSZ], |
| 117 | const void */*k*/, size_t /*ksz*/, |
| 118 | const octet /*K*/[ED25519_PUBSZ], |
| 119 | int /*phflag*/, |
| 120 | const void */*p*/, size_t /*psz*/, |
| 121 | const void */*m*/, size_t /*msz*/); |
| 122 | |
| 123 | extern void ed25519_sign(octet /*sig*/[ED25519_SIGSZ], |
| 124 | const void */*k*/, size_t /*ksz*/, |
| 125 | const octet /*K*/[ED25519_PUBSZ], |
| 126 | const void */*m*/, size_t /*msz*/); |
| 127 | |
| 128 | /* --- @ed25519_verify@, @ed25519ctx_verify@ --- * |
| 129 | * |
| 130 | * Arguments: @const octet K[ED25519_PUBSZ]@ = public key |
| 131 | * @int phflag@ = whether the `message' has been hashed already |
| 132 | * @const void *p@ = personalization string |
| 133 | * @size_t psz@ = length of personalization string |
| 134 | * @const void *m@ = message to sign |
| 135 | * @size_t msz@ = length of message |
| 136 | * @const octet sig[ED25519_SIGSZ]@ = signature |
| 137 | * |
| 138 | * Returns: Zero if OK, negative on failure. |
| 139 | * |
| 140 | * Use: Verify a signature. |
| 141 | * |
| 142 | * In @ed25519ctx_verify@, if @phflag@ is @-1@ then you get |
| 143 | * plain old Ed25519: the personalization string pointer @p@ |
| 144 | * will be ignored. If @phflag > 0@ then the `message' @m@ |
| 145 | * should be a SHA512 hash of the actual message. |
| 146 | */ |
| 147 | |
| 148 | extern int ed25519ctx_verify(const octet /*K*/[ED25519_PUBSZ], |
| 149 | int /*phflag*/, |
| 150 | const void */*p*/, size_t /*psz*/, |
| 151 | const void */*m*/, size_t /*msz*/, |
| 152 | const octet /*sig*/[ED25519_SIGSZ]); |
| 153 | |
| 154 | extern int ed25519_verify(const octet /*K*/[ED25519_PUBSZ], |
| 155 | const void */*m*/, size_t /*msz*/, |
| 156 | const octet /*sig*/[ED25519_SIGSZ]); |
| 157 | |
| 158 | /*----- That's all, folks -------------------------------------------------*/ |
| 159 | |
| 160 | #ifdef __cplusplus |
| 161 | } |
| 162 | #endif |
| 163 | |
| 164 | #endif |