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/* Copyright (c) 2016, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#ifndef OPENSSL_HEADER_NEWHOPE_H
#define OPENSSL_HEADER_NEWHOPE_H
#include <openssl/base.h>
#include <openssl/sha.h>
#if defined(__cplusplus)
extern "C" {
#endif
/* Post-quantum key agreement, based upon the reference
* implementation. Note: this implementation does not interoperate
* with the reference implementation!
*
* Source: https://github.com/tpoeppelmann/newhope
*
* The authors' permission to use their code is gratefully acknowledged. */
/* NEWHOPE_POLY_new returns a new |NEWHOPE_POLY| object, or NULL on error. */
OPENSSL_EXPORT NEWHOPE_POLY *NEWHOPE_POLY_new(void);
/* NEWHOPE_POLY_free frees |p|. */
OPENSSL_EXPORT void NEWHOPE_POLY_free(NEWHOPE_POLY *p);
/* NEWHOPE_POLY_LENGTH is the size in bytes of the packed representation of a
* polynomial, encoded with 14 bits per coefficient. */
#define NEWHOPE_POLY_LENGTH ((1024 * 14) / 8)
/* NEWHOPE_RECONCILIATION_LENGTH is the size in bytes of the packed
* representation of the reconciliation data, encoded as 2 bits per
* coefficient. */
#define NEWHOPE_RECONCILIATION_LENGTH ((1024 * 2) / 8)
/* NEWHOPE_OFFERMSG_LENGTH is the length of the offering party's message to the
* accepting party. */
#define NEWHOPE_OFFERMSG_LENGTH (NEWHOPE_POLY_LENGTH + 32)
/* NEWHOPE_ACCEPTMSG_LENGTH is the length of the accepting party's message to
* the offering party. */
#define NEWHOPE_ACCEPTMSG_LENGTH \
(NEWHOPE_POLY_LENGTH + NEWHOPE_RECONCILIATION_LENGTH)
/* NEWHOPE_KEY_LENGTH is the size of the result of the key agreement. This
* result is not exposed to callers: instead, it is whitened with SHA-256, whose
* output happens to be the same size. */
#define NEWHOPE_KEY_LENGTH 32
/* NEWHOPE_offer initializes |out_msg| and |out_sk| for a new key
* exchange. |msg| must have room for |NEWHOPE_OFFERMSG_LENGTH| bytes. Neither
* output may be cached. */
OPENSSL_EXPORT void NEWHOPE_offer(uint8_t out_msg[NEWHOPE_OFFERMSG_LENGTH],
NEWHOPE_POLY *out_sk);
/* NEWHOPE_accept completes a key exchange given an offer message |msg|. The
* result of the key exchange is written to |out_key|, which must have space for
* |SHA256_DIGEST_LENGTH| bytes. The message to be send to the offering party is
* written to |out_msg|, which must have room for |NEWHOPE_ACCEPTMSG_LENGTH|
* bytes. Returns 1 on success and 0 on error. */
OPENSSL_EXPORT int NEWHOPE_accept(uint8_t out_key[SHA256_DIGEST_LENGTH],
uint8_t out_msg[NEWHOPE_ACCEPTMSG_LENGTH],
const uint8_t msg[NEWHOPE_OFFERMSG_LENGTH],
size_t msg_len);
/* NEWHOPE_finish completes a key exchange for the offering party, given an
* accept message |msg| and the previously generated secret |sk|. The result of
* the key exchange is written to |out_key|, which must have space for
* |SHA256_DIGEST_LENGTH| bytes. Returns 1 on success and 0 on error. */
OPENSSL_EXPORT int NEWHOPE_finish(uint8_t out_key[SHA256_DIGEST_LENGTH],
const NEWHOPE_POLY *sk,
const uint8_t msg[NEWHOPE_ACCEPTMSG_LENGTH],
size_t msg_len);
/* Lower-level functions. */
/* NEWHOPE_POLY_noise sets |r| to a random polynomial where the coefficients are
* sampled from the noise distribution. */
OPENSSL_EXPORT void NEWHOPE_POLY_noise(NEWHOPE_POLY* r);
/* NEWHOPE_POLY_noise_ntt sets |r| to an output of NEWHOPE_POLY_noise, and then
* applies NTT(r) in-place. */
OPENSSL_EXPORT void NEWHOPE_POLY_noise_ntt(NEWHOPE_POLY* r);
/* NEWHOPE_offer_computation is the work of |NEWHOPE_offer|, less the encoding
* parts. The inputs are the noise polynomials |s| and |e|, and random
* polynomial |a|. The output is the polynomial |pk|. */
OPENSSL_EXPORT void NEWHOPE_offer_computation(
NEWHOPE_POLY *out_pk,
const NEWHOPE_POLY *s, const NEWHOPE_POLY *e, const NEWHOPE_POLY *a);
/* NEWHOPE_accept_computation is the work of |NEWHOPE_accept|, less the encoding
* parts. The inputs from the peer are |pk| and |a|. The locally-generated
* inputs are the noise polynomials |sp|, |ep|, and |epp|, and the random bytes
* |rand|. The outputs are |out_bp| and |out_reconciliation|, and the result of
* key agreement |key|. Returns 1 on success and 0 on failure. */
OPENSSL_EXPORT void NEWHOPE_accept_computation(
uint8_t out_key[NEWHOPE_KEY_LENGTH], NEWHOPE_POLY *out_bp,
NEWHOPE_POLY *out_reconciliation,
const NEWHOPE_POLY *sp, const NEWHOPE_POLY *ep, const NEWHOPE_POLY *epp,
const uint8_t rand[32],
const NEWHOPE_POLY *pk, const NEWHOPE_POLY *a);
/* NEWHOPE_finish_computation is the work of |NEWHOPE_finish|, less the encoding
* parts. Given the peer's |bp| and |reconciliation|, and locally-generated
* noise |noise|, the result of the key agreement is written to out_key.
* Returns 1 on success and 0 on failure. */
OPENSSL_EXPORT void NEWHOPE_finish_computation(
uint8_t out_key[NEWHOPE_KEY_LENGTH], const NEWHOPE_POLY *noise,
const NEWHOPE_POLY *bp, const NEWHOPE_POLY *reconciliation);
/* NEWHOPE_POLY_frombytes decodes |a| into |r|. */
OPENSSL_EXPORT void NEWHOPE_POLY_frombytes(
NEWHOPE_POLY *r, const uint8_t a[NEWHOPE_POLY_LENGTH]);
/* NEWHOPE_POLY_tobytes packs the polynomial |p| into the compact representation
* |r|. */
OPENSSL_EXPORT void NEWHOPE_POLY_tobytes(uint8_t r[NEWHOPE_POLY_LENGTH],
const NEWHOPE_POLY* p);
/* NEWHOPE_offer_frommsg decodes an offer message |msg| into its constituent
* polynomials |out_pk| and |a|. */
OPENSSL_EXPORT void NEWHOPE_offer_frommsg(
NEWHOPE_POLY *out_pk, NEWHOPE_POLY *out_a,
const uint8_t msg[NEWHOPE_OFFERMSG_LENGTH]);
#if defined(__cplusplus)
} /* extern "C" */
#endif
#endif /* OPENSSL_HEADER_NEWHOPE_H */