104 lines
4.3 KiB
C
104 lines
4.3 KiB
C
/*
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* Copyright (c) 2015, Lars Schmertmann <SmallLars@t-online.de>,
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* Jens Trillmann <jtrillma@informatik.uni-bremen.de>.
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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
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* 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,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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*/
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/**
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* \file
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* Calculations on elliptic curve secp256r1
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*
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* This is a efficient ECC implementation on the secp256r1 curve for
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* 32 Bit CPU architectures. It provides basic operations on the
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* secp256r1 curve and support for ECDH and ECDSA.
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*
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* \author
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* Lars Schmertmann <SmallLars@t-online.de>
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* Jens Trillmann <jtrillma@informatik.uni-bremen.de>
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*/
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#ifndef ECC_H_
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#define ECC_H_
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#include <stdint.h>
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/**
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* \brief Checks if a (random) number is valid as scalar on elliptic curve secp256r1
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*
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* A (random) number is only usable as scalar on elliptic curve secp256r1 if
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* it is lower than the order of the curve. For the check, you need to provide
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* the order of elliptic curve secp256r1.
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*
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* uint32_t order[8] = {0xFC632551, 0xF3B9CAC2, 0xA7179E84, 0xBCE6FAAD, 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0xFFFFFFFF};
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*
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* \param key The (random) number to check for usability
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* \param order The order of elliptic curve secp256r1
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*
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* \return 1 if key is valid
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*/
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#define ecc_is_valid_key(key, order) (ecc_compare(order, key) == 1)
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/**
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* \brief Compares the value of a with the value of b
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*
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* This function is only public because its needed for the macro ecc_is_valid_key.
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* It does a comparison of two 256 bit numbers. The return values are 1, 0 or -1.
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*
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* \param a First number
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* \param b Second number
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*
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* \return 1 if a is greater than b
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0 if a is equal to b
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-1 if a is less than b
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*/
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int32_t ecc_compare(const uint32_t *a, const uint32_t *b);
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/**
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* \brief ECC scalar multiplication on elliptic curve secp256r1
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*
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* This function does a scalar multiplication on elliptic curve secp256r1.
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* For an Elliptic curve Diffie–Hellman you need two multiplications. First one
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* with the base point of elliptic curve secp256r1 you need to provide.
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*
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* uint32_t base_x[8] = {0xd898c296, 0xf4a13945, 0x2deb33a0, 0x77037d81, 0x63a440f2, 0xf8bce6e5, 0xe12c4247, 0x6b17d1f2};
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* uint32_t base_y[8] = {0x37bf51f5, 0xcbb64068, 0x6b315ece, 0x2bce3357, 0x7c0f9e16, 0x8ee7eb4a, 0xfe1a7f9b, 0x4fe342e2};
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*
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* \param resultx Pointer to memory to store the x-coordinate of the result
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* \param resulty Pointer to memory to store the y-coordinate of the result
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* \param px x-coordinate of the point to multiply with scalar
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* \param py y-coordinate of the point to multiply with scalar
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* \param secret Scalar for multiplication with elliptic curve point
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*/
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void ecc_ec_mult(uint32_t *resultx, uint32_t *resulty, const uint32_t *px, const uint32_t *py, const uint32_t *secret);
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#endif /* ECC_H_ */
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