BN_zero.3ossl 6.0 KB

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  133. .\" ========================================================================
  134. .\"
  135. .IX Title "BN_ZERO 3ossl"
  136. .TH BN_ZERO 3ossl "2024-09-03" "3.3.2" "OpenSSL"
  137. .\" For nroff, turn off justification. Always turn off hyphenation; it makes
  138. .\" way too many mistakes in technical documents.
  139. .if n .ad l
  140. .nh
  141. .SH "NAME"
  142. BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word \- BIGNUM assignment
  143. operations
  144. .SH "SYNOPSIS"
  145. .IX Header "SYNOPSIS"
  146. .Vb 1
  147. \& #include <openssl/bn.h>
  148. \&
  149. \& void BN_zero(BIGNUM *a);
  150. \& int BN_one(BIGNUM *a);
  151. \&
  152. \& const BIGNUM *BN_value_one(void);
  153. \&
  154. \& int BN_set_word(BIGNUM *a, BN_ULONG w);
  155. \& unsigned BN_ULONG BN_get_word(BIGNUM *a);
  156. .Ve
  157. .SH "DESCRIPTION"
  158. .IX Header "DESCRIPTION"
  159. \&\fB\s-1BN_ULONG\s0\fR is a macro that will be an unsigned integral type optimized
  160. for the most efficient implementation on the local platform.
  161. .PP
  162. \&\fBBN_zero()\fR, \fBBN_one()\fR and \fBBN_set_word()\fR set \fBa\fR to the values 0, 1 and
  163. \&\fBw\fR respectively. \fBBN_zero()\fR and \fBBN_one()\fR are macros.
  164. .PP
  165. \&\fBBN_value_one()\fR returns a \fB\s-1BIGNUM\s0\fR constant of value 1. This constant
  166. is useful for use in comparisons and assignment.
  167. .PP
  168. \&\fBBN_get_word()\fR returns \fBa\fR, if it can be represented as a \fB\s-1BN_ULONG\s0\fR.
  169. .SH "RETURN VALUES"
  170. .IX Header "RETURN VALUES"
  171. \&\fBBN_get_word()\fR returns the value \fBa\fR, or all-bits-set if \fBa\fR cannot
  172. be represented as a single integer.
  173. .PP
  174. \&\fBBN_one()\fR and \fBBN_set_word()\fR return 1 on success, 0 otherwise.
  175. \&\fBBN_value_one()\fR returns the constant.
  176. \&\fBBN_zero()\fR never fails and returns no value.
  177. .SH "BUGS"
  178. .IX Header "BUGS"
  179. If a \fB\s-1BIGNUM\s0\fR is equal to the value of all-bits-set, it will collide
  180. with the error condition returned by \fBBN_get_word()\fR which uses that
  181. as an error value.
  182. .PP
  183. \&\fB\s-1BN_ULONG\s0\fR should probably be a typedef.
  184. .SH "SEE ALSO"
  185. .IX Header "SEE ALSO"
  186. \&\fBBN_bn2bin\fR\|(3)
  187. .SH "HISTORY"
  188. .IX Header "HISTORY"
  189. In OpenSSL 0.9.8, \fBBN_zero()\fR was changed to not return a value; previous
  190. versions returned an int.
  191. .SH "COPYRIGHT"
  192. .IX Header "COPYRIGHT"
  193. Copyright 2000\-2018 The OpenSSL Project Authors. All Rights Reserved.
  194. .PP
  195. Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use
  196. this file except in compliance with the License. You can obtain a copy
  197. in the file \s-1LICENSE\s0 in the source distribution or at
  198. <https://www.openssl.org/source/license.html>.