1*cca6fc52SDaniel Fojt /* $OpenBSD: curve25519.h,v 1.3 2019/05/11 15:55:52 tb Exp $ */ 272c33676SMaxim Ag /* 372c33676SMaxim Ag * Copyright (c) 2015, Google Inc. 472c33676SMaxim Ag * 572c33676SMaxim Ag * Permission to use, copy, modify, and/or distribute this software for any 672c33676SMaxim Ag * purpose with or without fee is hereby granted, provided that the above 772c33676SMaxim Ag * copyright notice and this permission notice appear in all copies. 872c33676SMaxim Ag * 972c33676SMaxim Ag * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 1072c33676SMaxim Ag * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 1172c33676SMaxim Ag * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 1272c33676SMaxim Ag * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 1372c33676SMaxim Ag * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 1472c33676SMaxim Ag * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 1572c33676SMaxim Ag * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 1672c33676SMaxim Ag */ 1772c33676SMaxim Ag 1872c33676SMaxim Ag #ifndef HEADER_CURVE25519_H 1972c33676SMaxim Ag #define HEADER_CURVE25519_H 2072c33676SMaxim Ag 2172c33676SMaxim Ag #include <stdint.h> 2272c33676SMaxim Ag 2372c33676SMaxim Ag #include <openssl/opensslconf.h> 2472c33676SMaxim Ag 2572c33676SMaxim Ag #if defined(__cplusplus) 2672c33676SMaxim Ag extern "C" { 2772c33676SMaxim Ag #endif 2872c33676SMaxim Ag 2972c33676SMaxim Ag /* 3072c33676SMaxim Ag * Curve25519. 3172c33676SMaxim Ag * 3272c33676SMaxim Ag * Curve25519 is an elliptic curve. See https://tools.ietf.org/html/rfc7748. 3372c33676SMaxim Ag */ 3472c33676SMaxim Ag 3572c33676SMaxim Ag /* 3672c33676SMaxim Ag * X25519. 3772c33676SMaxim Ag * 3872c33676SMaxim Ag * X25519 is the Diffie-Hellman primitive built from curve25519. It is 3972c33676SMaxim Ag * sometimes referred to as curve25519, but X25519 is a more precise name. 4072c33676SMaxim Ag * See http://cr.yp.to/ecdh.html and https://tools.ietf.org/html/rfc7748. 4172c33676SMaxim Ag */ 4272c33676SMaxim Ag 4372c33676SMaxim Ag #define X25519_KEY_LENGTH 32 4472c33676SMaxim Ag 4572c33676SMaxim Ag /* 4672c33676SMaxim Ag * X25519_keypair sets |out_public_value| and |out_private_key| to a freshly 4772c33676SMaxim Ag * generated, public/private key pair. 4872c33676SMaxim Ag */ 4972c33676SMaxim Ag void X25519_keypair(uint8_t out_public_value[X25519_KEY_LENGTH], 5072c33676SMaxim Ag uint8_t out_private_key[X25519_KEY_LENGTH]); 5172c33676SMaxim Ag 5272c33676SMaxim Ag /* 5372c33676SMaxim Ag * X25519 writes a shared key to |out_shared_key| that is calculated from the 5472c33676SMaxim Ag * given private key and the peer's public value. It returns one on success and 5572c33676SMaxim Ag * zero on error. 5672c33676SMaxim Ag * 5772c33676SMaxim Ag * Don't use the shared key directly, rather use a KDF and also include the two 5872c33676SMaxim Ag * public values as inputs. 5972c33676SMaxim Ag */ 6072c33676SMaxim Ag int X25519(uint8_t out_shared_key[X25519_KEY_LENGTH], 6172c33676SMaxim Ag const uint8_t private_key[X25519_KEY_LENGTH], 6272c33676SMaxim Ag const uint8_t peers_public_value[X25519_KEY_LENGTH]); 6372c33676SMaxim Ag 6472c33676SMaxim Ag #if defined(__cplusplus) 6572c33676SMaxim Ag } /* extern C */ 6672c33676SMaxim Ag #endif 6772c33676SMaxim Ag 6872c33676SMaxim Ag #endif /* HEADER_CURVE25519_H */ 69