46 lines
1.6 KiB
C
46 lines
1.6 KiB
C
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/*
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* Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/* Internal EC functions for other submodules: not for application use */
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#ifndef HEADER_OSSL_EC_INTERNAL_H
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# define HEADER_OSSL_EC_INTERNAL_H
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# include <openssl/opensslconf.h>
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# ifndef OPENSSL_NO_EC
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# include <openssl/ec.h>
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/*-
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* Computes the multiplicative inverse of x in the range
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* [1,EC_GROUP::order), where EC_GROUP::order is the cardinality of the
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* subgroup generated by the generator G:
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*
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* res := x^(-1) (mod EC_GROUP::order).
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*
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* This function expects the following two conditions to hold:
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* - the EC_GROUP order is prime, and
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* - x is included in the range [1, EC_GROUP::order).
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*
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* This function returns 1 on success, 0 on error.
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*
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* If the EC_GROUP order is even, this function explicitly returns 0 as
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* an error.
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* In case any of the two conditions stated above is not satisfied,
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* the correctness of its output is not guaranteed, even if the return
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* value could still be 1 (as primality testing and a conditional modular
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* reduction round on the input can be omitted by the underlying
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* implementations for better SCA properties on regular input values).
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*/
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__owur int ec_group_do_inverse_ord(const EC_GROUP *group, BIGNUM *res,
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const BIGNUM *x, BN_CTX *ctx);
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# endif /* OPENSSL_NO_EC */
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#endif
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