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62 lines
2.6 KiB
C
62 lines
2.6 KiB
C
/***********************************************************************
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* Copyright (c) 2013, 2014, 2017 Pieter Wuille, Andrew Poelstra *
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* Distributed under the MIT software license, see the accompanying *
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* file COPYING or https://www.opensource.org/licenses/mit-license.php.*
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***********************************************************************/
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#ifndef SECP256K1_ECMULT_H
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#define SECP256K1_ECMULT_H
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#include "group.h"
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#include "scalar.h"
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#include "scratch.h"
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#ifndef ECMULT_WINDOW_SIZE
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# define ECMULT_WINDOW_SIZE 15
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# ifdef DEBUG_CONFIG
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# pragma message DEBUG_CONFIG_MSG("ECMULT_WINDOW_SIZE undefined, assuming default value")
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# endif
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#endif
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#ifdef DEBUG_CONFIG
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# pragma message DEBUG_CONFIG_DEF(ECMULT_WINDOW_SIZE)
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#endif
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/* Noone will ever need more than a window size of 24. The code might
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* be correct for larger values of ECMULT_WINDOW_SIZE but this is not
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* tested.
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*
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* The following limitations are known, and there are probably more:
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* If WINDOW_G > 27 and size_t has 32 bits, then the code is incorrect
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* because the size of the memory object that we allocate (in bytes)
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* will not fit in a size_t.
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* If WINDOW_G > 31 and int has 32 bits, then the code is incorrect
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* because certain expressions will overflow.
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*/
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#if ECMULT_WINDOW_SIZE < 2 || ECMULT_WINDOW_SIZE > 24
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# error Set ECMULT_WINDOW_SIZE to an integer in range [2..24].
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#endif
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/** The number of entries a table with precomputed multiples needs to have. */
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#define ECMULT_TABLE_SIZE(w) (1L << ((w)-2))
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/** Double multiply: R = na*A + ng*G */
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static void secp256k1_ecmult(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng);
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typedef int (secp256k1_ecmult_multi_callback)(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data);
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/**
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* Multi-multiply: R = inp_g_sc * G + sum_i ni * Ai.
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* Chooses the right algorithm for a given number of points and scratch space
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* size. Resets and overwrites the given scratch space. If the points do not
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* fit in the scratch space the algorithm is repeatedly run with batches of
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* points. If no scratch space is given then a simple algorithm is used that
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* simply multiplies the points with the corresponding scalars and adds them up.
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* Returns: 1 on success (including when inp_g_sc is NULL and n is 0)
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* 0 if there is not enough scratch space for a single point or
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* callback returns 0
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*/
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static int secp256k1_ecmult_multi_var(const secp256k1_callback* error_callback, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n);
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#endif /* SECP256K1_ECMULT_H */
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