118 lines
4.0 KiB
C
118 lines
4.0 KiB
C
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/**
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* Copyright (c) 2019 - 2020, Nordic Semiconductor ASA
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form, except as embedded into a Nordic
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* Semiconductor ASA integrated circuit in a product or a software update for
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* such product, must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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*
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* 3. Neither the name of Nordic Semiconductor ASA nor the names of its
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* contributors may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* 4. This software, with or without modification, must only be used with a
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* Nordic Semiconductor ASA integrated circuit.
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*
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* 5. Any software provided in binary form under this license must not be reverse
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* engineered, decompiled, modified and/or disassembled.
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*
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* THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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/**@file
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* @defgroup nrf_oberon_curve25519 ECC Curve25519 low-level APIs
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* @ingroup nrf_oberon
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* @{
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* @brief Type declarations and APIs for low-level elliptic curve point operations
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* based on Curve25519.
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*
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* Curve25519 is an elliptic curve offering 128 bits of security. It is designed
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* for use in the Elliptic Curve Diffie-Hellman (ECDH) key agreement scheme.
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*
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* @see [RFC 7748 - Elliptic Curves for Security](https://tools.ietf.org/html/rfc7748)
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* @see [Curve25519: high-speed elliptic-curve cryptography](http://cr.yp.to/ecdh.html)
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*/
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#ifndef OCRYPTO_CURVE25519_H
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#define OCRYPTO_CURVE25519_H
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* Length of a scalar.
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*/
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#define ocrypto_curve25519_SCALAR_BYTES (32)
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/**
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* Length of a curve point.
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*/
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#define ocrypto_curve25519_BYTES (32)
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/**
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* Curve25519 scalar multiplication `r = n * basePoint`.
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*
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* Given a secret key @p n, the corresponding Curve25519 public key is computed
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* and put into @p r.
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*
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* The inverse of this function is difficult to compute.
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*
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* @param[out] r Resulting curve point.
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* @param[in] n Scalar factor.
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*
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* @remark @p r and @p n can point to the same address.
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*/
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void ocrypto_curve25519_scalarmult_base(
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uint8_t r[ocrypto_curve25519_BYTES],
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const uint8_t n[ocrypto_curve25519_SCALAR_BYTES]);
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/**
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* Curve25519 scalar multiplication `r = n * p`.
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*
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* A shared secret is computed from the local secret key @p n and another
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* party's public key @p p and put into @p r. The same shared secret is
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* generated when the other party combines its private key with the local public
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* key.
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*
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* @param[out] r Resulting curve point.
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* @param[in] n Scalar factor.
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* @param[in] p Point factor.
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*
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* @remark @p r and @p n can point to the same address.
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*/
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void ocrypto_curve25519_scalarmult(
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uint8_t r[ocrypto_curve25519_BYTES],
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const uint8_t n[ocrypto_curve25519_SCALAR_BYTES],
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const uint8_t p[ocrypto_curve25519_BYTES]);
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#ifdef __cplusplus
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}
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#endif
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#endif /* #ifndef OCRYPTO_CURVE25519_H */
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/** @} */
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