BN_zero.3ssl - Man Page

BIGNUM assignment operations


 #include <openssl/bn.h>

 void BN_zero(BIGNUM *a);
 int BN_one(BIGNUM *a);

 const BIGNUM *BN_value_one(void);

 int BN_set_word(BIGNUM *a, BN_ULONG w);
 unsigned BN_ULONG BN_get_word(BIGNUM *a);


BN_ULONG is a macro that will be an unsigned integral type optimized for the most efficient implementation on the local platform.

BN_zero(), BN_one() and BN_set_word() set a to the values 0, 1 and w respectively.  BN_zero() and BN_one() are macros.

BN_value_one() returns a BIGNUM constant of value 1. This constant is useful for use in comparisons and assignment.

BN_get_word() returns a, if it can be represented as a BN_ULONG.

Return Values

BN_get_word() returns the value a, or all-bits-set if a cannot be represented as a single integer.

BN_one() and BN_set_word() return 1 on success, 0 otherwise. BN_value_one() returns the constant. BN_zero() never fails and returns no value.


If a BIGNUM is equal to the value of all-bits-set, it will collide with the error condition returned by BN_get_word() which uses that as an error value.

BN_ULONG should probably be a typedef.

See Also



In OpenSSL 0.9.8, BN_zero() was changed to not return a value; previous versions returned an int.

Referenced By


The man pages BN_get_word.3ssl(3), BN_one.3ssl(3), BN_set_word.3ssl(3) and BN_value_one.3ssl(3) are aliases of BN_zero.3ssl(3).

2022-07-21 1.1.1q OpenSSL