1 /* 2 * Copyright (c) 2015, Google Inc. 3 * 4 * Permission to use, copy, modify, and/or distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 11 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 13 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 14 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 #ifndef HEADER_CURVE25519_H 18 #define HEADER_CURVE25519_H 19 20 #include <stdint.h> 21 22 #include <openssl/opensslconf.h> 23 24 #if defined(__cplusplus) 25 extern "C" { 26 #endif 27 28 /* 29 * Curve25519. 30 * 31 * Curve25519 is an elliptic curve. See https://tools.ietf.org/html/rfc7748. 32 */ 33 34 /* 35 * X25519. 36 * 37 * X25519 is the Diffie-Hellman primitive built from curve25519. It is 38 * sometimes referred to as curve25519, but X25519 is a more precise name. 39 * See http://cr.yp.to/ecdh.html and https://tools.ietf.org/html/rfc7748. 40 */ 41 42 /* 43 * X25519_keypair sets |out_public_value| and |out_private_key| to a freshly 44 * generated, public/private key pair. 45 */ 46 void X25519_keypair(uint8_t out_public_value[32], uint8_t out_private_key[32]); 47 48 /* 49 * X25519 writes a shared key to |out_shared_key| that is calculated from the 50 * given private key and the peer's public value. It returns one on success and 51 * zero on error. 52 * 53 * Don't use the shared key directly, rather use a KDF and also include the two 54 * public values as inputs. 55 */ 56 int X25519(uint8_t out_shared_key[32], const uint8_t private_key[32], 57 const uint8_t peers_public_value[32]); 58 59 #if defined(__cplusplus) 60 } /* extern C */ 61 #endif 62 63 #endif /* HEADER_CURVE25519_H */ 64