- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- SEE ALSO
- HISTORY
- AUTHOR

# 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_get_thread_id, BN_BLINDING_set_thread_id, 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);
     #ifndef OPENSSL_NO_DEPRECATED
     unsigned long BN_BLINDING_get_thread_id(const BN_BLINDING *);
     void BN_BLINDING_set_thread_id(BN_BLINDING *, unsigned long);
     #endif
     CRYPTO_THREADID *BN_BLINDING_thread_id(BN_BLINDING *);
     unsigned long BN_BLINDING_get_flags(const BN_BLINDING *);
     void BN_BLINDING_set_flags(BN_BLINDING *, unsigned long);
     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.

`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_thread_id()` provides access to the CRYPTO_THREADID object within the BN_BLINDING structure. This is to help users provide proper locking if needed for multi-threaded use. The "thread id" object of a newly allocated BN_BLINDING structure is initialised to the thread id in which `BN_BLINDING_new()` was called.

`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 occured.

`BN_BLINDING_thread_id()` returns a pointer to the thread id object within a BN_BLINDING object.

`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.

# SEE ALSO

bn

# 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.

BN_BLINDING_convert_ex, BN_BLINDIND_invert_ex, BN_BLINDING_get_thread_id, BN_BLINDING_set_thread_id, BN_BLINDING_set_flags, BN_BLINDING_get_flags and BN_BLINDING_create_param were first introduced in OpenSSL 0.9.8

# AUTHOR

Nils Larsch for the OpenSSL project (http://www.openssl.org).