|BN_NEW(3)||Library Functions Manual||BN_NEW(3)|
BN_clear_free — allocate and
The BN library performs arithmetic operations on integers of arbitrary size. It was written for use in public key cryptography, such as RSA and Diffie-Hellman.
It uses dynamic memory allocation for storing its data structures. That means that there is no limit on the size of the numbers manipulated by these functions, but return values must always be checked in case a memory allocation error has occurred.
The basic object in this library is a BIGNUM. It is used to hold a single large integer. This type should be considered opaque and fields should not be modified or accessed directly.
BN_new() allocates and initializes a
BIGNUM structure, in particular setting the value to
zero and the flags to
BN_FLG_CONSTTIME is not set
BN_init() initializes an existing
uninitialized BIGNUM. It is deprecated and dangerous:
BN_clear() is used to destroy sensitive
data such as keys when they are no longer needed. It erases the memory used
by a and sets it to the value 0.
BN_free() frees the components of the
BIGNUM and, if it was created by
BN_new(), also the structure itself.
BN_clear_free() additionally overwrites the data
before the memory is returned to the system. If a is a
NULL pointer, no action occurs.
BN_new() returns a pointer to the
BIGNUM. If the allocation fails, it returns
NULL and sets an error code that can be obtained by
BN_add(3), BN_add_word(3), BN_BLINDING_new(3), BN_bn2bin(3), BN_cmp(3), BN_copy(3), BN_CTX_new(3), BN_CTX_start(3), BN_generate_prime(3), BN_get0_nist_prime_521(3), BN_mod_inverse(3), BN_mod_mul_montgomery(3), BN_mod_mul_reciprocal(3), BN_num_bytes(3), BN_rand(3), BN_set_bit(3), BN_set_flags(3), BN_set_negative(3), BN_swap(3), BN_zero(3), crypto(3), get_rfc3526_prime_8192(3)
BN_clear_free() first appeared in SSLeay 0.5.1 and
have been available since OpenBSD 2.4.
BN_init() first appeared in SSLeay 0.9.1
and has been available since OpenBSD 2.6.
BN_init() must not be called on a
BIGNUM that was used and contains an actual number, or
the memory used for storing the number is leaked immediately. Besides, it
must not be called on a number allocated with
BN_new(), or the BIGNUM
structure itself will likely be leaked later on. It can only be used on
static BIGNUM structures, on
BIGNUM structures on the stack, or on
malloc(3)'ed manually, but all of these
options are discouraged because they will no longer work once the
BIGNUM data type is made opaque.
|June 10, 2019||OpenBSD-current|