1 /* $OpenBSD: curve25519.h,v 1.7 2022/11/13 14:05:04 tb Exp $ */ 2 /* 3 * Copyright (c) 2015, Google Inc. 4 * 5 * Permission to use, copy, modify, and/or distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 12 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 14 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 15 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #ifndef HEADER_CURVE25519_H 19 #define HEADER_CURVE25519_H 20 21 #include <stdint.h> 22 23 #include <openssl/opensslconf.h> 24 25 #if defined(__cplusplus) 26 extern "C" { 27 #endif 28 29 /* 30 * Curve25519. 31 * 32 * Curve25519 is an elliptic curve. See https://tools.ietf.org/html/rfc7748. 33 */ 34 35 /* 36 * X25519. 37 * 38 * X25519 is the Diffie-Hellman primitive built from curve25519. It is 39 * sometimes referred to as curve25519, but X25519 is a more precise name. 40 * See http://cr.yp.to/ecdh.html and https://tools.ietf.org/html/rfc7748. 41 */ 42 43 #define X25519_KEY_LENGTH 32 44 45 /* 46 * X25519_keypair sets |out_public_value| and |out_private_key| to a freshly 47 * generated, public/private key pair. 48 */ 49 void X25519_keypair(uint8_t out_public_value[X25519_KEY_LENGTH], 50 uint8_t out_private_key[X25519_KEY_LENGTH]); 51 52 /* 53 * X25519 writes a shared key to |out_shared_key| that is calculated from the 54 * given private key and the peer's public value. It returns one on success and 55 * zero on error. 56 * 57 * Don't use the shared key directly, rather use a KDF and also include the two 58 * public values as inputs. 59 */ 60 int X25519(uint8_t out_shared_key[X25519_KEY_LENGTH], 61 const uint8_t private_key[X25519_KEY_LENGTH], 62 const uint8_t peers_public_value[X25519_KEY_LENGTH]); 63 64 /* 65 * ED25519 66 * 67 * Ed25519 is a signature scheme using a twisted Edwards curve that is 68 * birationally equivalent to curve25519. 69 */ 70 71 #define ED25519_PRIVATE_KEY_LENGTH 32 72 #define ED25519_PUBLIC_KEY_LENGTH 32 73 #define ED25519_SIGNATURE_LENGTH 64 74 75 /* 76 * ED25519_keypair sets |out_public_key| and |out_private_key| to a freshly 77 * generated, public/private key pair. 78 */ 79 void ED25519_keypair(uint8_t out_public_key[ED25519_PUBLIC_KEY_LENGTH], 80 uint8_t out_private_key[ED25519_PRIVATE_KEY_LENGTH]); 81 82 /* 83 * ED25519_sign sets |out_sig| to be a signature of |message_len| bytes from 84 * |message| using |public_key| and |private_key|. It returns one on success 85 * or zero on allocation failure. 86 */ 87 int ED25519_sign(uint8_t *out_sig, const uint8_t *message, size_t message_len, 88 const uint8_t public_key[ED25519_PUBLIC_KEY_LENGTH], 89 const uint8_t private_key_seed[ED25519_PRIVATE_KEY_LENGTH]); 90 91 /* 92 * ED25519_verify returns one iff |signature| is a valid signature by 93 * |public_key| of |message_len| bytes from |message|. It returns zero 94 * otherwise. 95 */ 96 int ED25519_verify(const uint8_t *message, size_t message_len, 97 const uint8_t signature[ED25519_SIGNATURE_LENGTH], 98 const uint8_t public_key[ED25519_PUBLIC_KEY_LENGTH]); 99 100 #if defined(__cplusplus) 101 } /* extern C */ 102 #endif 103 104 #endif /* HEADER_CURVE25519_H */ 105