BN_ADD_WORD(3) Library Functions Manual BN_ADD_WORD(3)

BN_add_word, BN_sub_word, BN_mul_word, BN_div_word, BN_mod_wordarithmetic functions on BIGNUMs with integers

#include <openssl/bn.h>

BN_add_word(BIGNUM *a, BN_ULONG w);

BN_sub_word(BIGNUM *a, BN_ULONG w);

BN_mul_word(BIGNUM *a, BN_ULONG w);

BN_div_word(BIGNUM *a, BN_ULONG w);

BN_mod_word(const BIGNUM *a, BN_ULONG w);

These functions perform arithmetic operations on BIGNUMs with unsigned integers. They are much more efficient than the normal BIGNUM arithmetic operations.

BN_ULONG is a macro that expands to unsigned long (= uint64_t) on _LP64 platforms and unsigned int (= uint32_t) elsewhere.

() adds w to a (a+=w).

() subtracts w from a (a-=w).

() multiplies a and w (a*=w).

() divides a by w (a/=w) and returns the remainder.

() returns the remainder of a divided by w (a%w).

For () and BN_mod_word(), w must not be 0.

BN_add_word(), BN_sub_word(), and BN_mul_word() return 1 for success or 0 on error. The error codes can be obtained by ERR_get_error(3).

BN_mod_word() and BN_div_word() return a%w on success and (BN_ULONG)-1 if an error occurred.

BN_add(3), BN_new(3)

BN_add_word(), BN_div_word(), and BN_mod_word() first appeared in SSLeay 0.5.1. BN_sub_word() and BN_mul_word() first appeared in SSLeay 0.9.0. All these functions have been available since OpenBSD 2.4.

Before 0.9.8a, the return value for BN_div_word() and BN_mod_word() in case of an error was 0.

November 22, 2022 OpenBSD 7.5