NAME

       BN_BLINDING_new, BN_BLINDING_free, BN_BLINDING_update, BN_BLINDING_convert,
       BN_BLINDING_invert, BN_BLINDING_convert_ex, BN_BLINDING_invert_ex,
       BN_BLINDING_is_current_thread, BN_BLINDING_set_current_thread, BN_BLINDING_lock,
       BN_BLINDING_unlock, BN_BLINDING_get_flags, BN_BLINDING_set_flags, BN_BLINDING_create_param
       - blinding related BIGNUM functions

SYNOPSIS

        #include <openssl/bn.h>

        BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai,
                                     BIGNUM *mod);
        void BN_BLINDING_free(BN_BLINDING *b);
        int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx);
        int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx);
        int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx);
        int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b,
                                   BN_CTX *ctx);
        int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
                                  BN_CTX *ctx);
        int BN_BLINDING_is_current_thread(BN_BLINDING *b);
        void BN_BLINDING_set_current_thread(BN_BLINDING *b);
        int BN_BLINDING_lock(BN_BLINDING *b);
        int BN_BLINDING_unlock(BN_BLINDING *b);
        unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b);
        void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags);
        BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
                                              const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
                                              int (*bn_mod_exp)(BIGNUM *r,
                                                                const BIGNUM *a,
                                                                const BIGNUM *p,
                                                                const BIGNUM *m,
                                                                BN_CTX *ctx,
                                                                BN_MONT_CTX *m_ctx),
                                              BN_MONT_CTX *m_ctx);

DESCRIPTION

       BN_BLINDING_new() allocates a new BN_BLINDING structure and copies the A and Ai values
       into the newly created BN_BLINDING object.

       BN_BLINDING_free() frees the BN_BLINDING structure.  If b is NULL, nothing is done.

       BN_BLINDING_update() updates the BN_BLINDING parameters by squaring the A and Ai or, after
       specific number of uses and if the necessary parameters are set, by re-creating the
       blinding parameters.

       BN_BLINDING_convert_ex() multiplies n with the blinding factor A.  If r is not NULL a copy
       the inverse blinding factor Ai will be returned in r (this is useful if a RSA object is
       shared among several threads). BN_BLINDING_invert_ex() multiplies n with the inverse
       blinding factor Ai. If r is not NULL it will be used as the inverse blinding.

       BN_BLINDING_convert() and BN_BLINDING_invert() are wrapper functions for
       BN_BLINDING_convert_ex() and BN_BLINDING_invert_ex() with r set to NULL.

       BN_BLINDING_is_current_thread() returns whether the BN_BLINDING structure is owned by the
       current thread. This is to help users provide proper locking if needed for multi-threaded
       use.

       BN_BLINDING_set_current_thread() sets the current thread as the owner of the BN_BLINDING
       structure.

       BN_BLINDING_lock() locks the BN_BLINDING structure.

       BN_BLINDING_unlock() unlocks the BN_BLINDING structure.

       BN_BLINDING_get_flags() returns the BN_BLINDING flags. Currently there are two supported
       flags: BN_BLINDING_NO_UPDATE and BN_BLINDING_NO_RECREATE. BN_BLINDING_NO_UPDATE inhibits
       the automatic update of the BN_BLINDING parameters after each use and
       BN_BLINDING_NO_RECREATE inhibits the automatic re-creation of the BN_BLINDING parameters
       after a fixed number of uses (currently 32). In newly allocated BN_BLINDING objects no
       flags are set.  BN_BLINDING_set_flags() sets the BN_BLINDING parameters flags.

       BN_BLINDING_create_param() creates new BN_BLINDING parameters using the exponent e and the
       modulus m. bn_mod_exp and m_ctx can be used to pass special functions for exponentiation
       (normally BN_mod_exp_mont() and BN_MONT_CTX).

RETURN VALUES

       BN_BLINDING_new() returns the newly allocated BN_BLINDING structure or NULL in case of an
       error.

       BN_BLINDING_update(), BN_BLINDING_convert(), BN_BLINDING_invert(),
       BN_BLINDING_convert_ex() and BN_BLINDING_invert_ex() return 1 on success and 0 if an error
       occurred.

       BN_BLINDING_is_current_thread() returns 1 if the current thread owns the BN_BLINDING
       object, 0 otherwise.

       BN_BLINDING_set_current_thread() doesn't return anything.

       BN_BLINDING_lock(), BN_BLINDING_unlock() return 1 if the operation succeeded or 0 on
       error.

       BN_BLINDING_get_flags() returns the currently set BN_BLINDING flags (a unsigned long
       value).

       BN_BLINDING_create_param() returns the newly created BN_BLINDING parameters or NULL on
       error.

HISTORY

       BN_BLINDING_thread_id() was first introduced in OpenSSL 1.0.0, and it deprecates
       BN_BLINDING_set_thread_id() and BN_BLINDING_get_thread_id().

COPYRIGHT

       Copyright 2005-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.