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BN_MOD_MUL_RECIPROCAL(3)	    OpenSSL	      BN_MOD_MUL_RECIPROCAL(3)

NAME
       BN_mod_mul_reciprocal, BN_div_recp, BN_RECP_CTX_new, BN_RECP_CTX_free,
       BN_RECP_CTX_set - modular multiplication	using reciprocal

SYNOPSIS
	#include <openssl/bn.h>

	BN_RECP_CTX *BN_RECP_CTX_new(void);
	void BN_RECP_CTX_free(BN_RECP_CTX *recp);

	int BN_RECP_CTX_set(BN_RECP_CTX	*recp, const BIGNUM *m,	BN_CTX *ctx);

	int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM	*a, BN_RECP_CTX	*recp,
			BN_CTX *ctx);

	int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *a,	BIGNUM *b,
				  BN_RECP_CTX *recp, BN_CTX *ctx);

DESCRIPTION
       BN_mod_mul_reciprocal() can be used to perform an efficient
       BN_mod_mul(3) operation when the	operation will be performed repeatedly
       with the	same modulus. It computes r=(a*b)%m using recp=1/m, which is
       set as described	below.	ctx is a previously allocated BN_CTX used for
       temporary variables.

       BN_RECP_CTX_new() allocates and initializes a BN_RECP structure.

       BN_RECP_CTX_free() frees	the components of the BN_RECP, and, if it was
       created by BN_RECP_CTX_new(), also the structure	itself.	 If recp is
       NULL, nothing is	done.

       BN_RECP_CTX_set() stores	m in recp and sets it up for computing 1/m and
       shifting	it left	by BN_num_bits(m)+1 to make it an integer. The result
       and the number of bits it was shifted left will later be	stored in
       recp.

       BN_div_recp() divides a by m using recp.	It places the quotient in dv
       and the remainder in rem.

       The BN_RECP_CTX structure cannot	be shared between threads.

RETURN VALUES
       BN_RECP_CTX_new() returns the newly allocated BN_RECP_CTX, and NULL on
       error.

       BN_RECP_CTX_free() has no return	value.

       For the other functions,	1 is returned for success, 0 on	error.	The
       error codes can be obtained by ERR_get_error(3).

SEE ALSO
       ERR_get_error(3), BN_add(3), BN_CTX_new(3)

HISTORY
       BN_RECP_CTX_init() was removed in OpenSSL 1.1.0

COPYRIGHT
       Copyright 2000-2017 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the OpenSSL license (the "License").  You	may not	use
       this file except	in compliance with the License.	 You can obtain	a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.

1.1.1a				  2018-11-20	      BN_MOD_MUL_RECIPROCAL(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | HISTORY | COPYRIGHT

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