BN_bn2bin.3 7.7 KB

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  131. .IX Title "BN_bn2bin 3"
  132. .TH BN_bn2bin 3 "2019-09-12" "1.0.2g" "OpenSSL"
  133. .\" For nroff, turn off justification. Always turn off hyphenation; it makes
  134. .\" way too many mistakes in technical documents.
  135. .if n .ad l
  136. .nh
  137. .SH "NAME"
  138. BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn,
  139. BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn \- format conversions
  140. .SH "SYNOPSIS"
  141. .IX Header "SYNOPSIS"
  142. .Vb 1
  143. \& #include <openssl/bn.h>
  144. \&
  145. \& int BN_bn2bin(const BIGNUM *a, unsigned char *to);
  146. \& BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
  147. \&
  148. \& char *BN_bn2hex(const BIGNUM *a);
  149. \& char *BN_bn2dec(const BIGNUM *a);
  150. \& int BN_hex2bn(BIGNUM **a, const char *str);
  151. \& int BN_dec2bn(BIGNUM **a, const char *str);
  152. \&
  153. \& int BN_print(BIO *fp, const BIGNUM *a);
  154. \& int BN_print_fp(FILE *fp, const BIGNUM *a);
  155. \&
  156. \& int BN_bn2mpi(const BIGNUM *a, unsigned char *to);
  157. \& BIGNUM *BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret);
  158. .Ve
  159. .SH "DESCRIPTION"
  160. .IX Header "DESCRIPTION"
  161. \&\fIBN_bn2bin()\fR converts the absolute value of \fBa\fR into big-endian form
  162. and stores it at \fBto\fR. \fBto\fR must point to BN_num_bytes(\fBa\fR) bytes of
  163. memory.
  164. .PP
  165. \&\fIBN_bin2bn()\fR converts the positive integer in big-endian form of length
  166. \&\fBlen\fR at \fBs\fR into a \fB\s-1BIGNUM\s0\fR and places it in \fBret\fR. If \fBret\fR is
  167. \&\s-1NULL,\s0 a new \fB\s-1BIGNUM\s0\fR is created.
  168. .PP
  169. \&\fIBN_bn2hex()\fR and \fIBN_bn2dec()\fR return printable strings containing the
  170. hexadecimal and decimal encoding of \fBa\fR respectively. For negative
  171. numbers, the string is prefaced with a leading '\-'. The string must be
  172. freed later using \fIOPENSSL_free()\fR.
  173. .PP
  174. \&\fIBN_hex2bn()\fR converts the string \fBstr\fR containing a hexadecimal number
  175. to a \fB\s-1BIGNUM\s0\fR and stores it in **\fBbn\fR. If *\fBbn\fR is \s-1NULL,\s0 a new
  176. \&\fB\s-1BIGNUM\s0\fR is created. If \fBbn\fR is \s-1NULL,\s0 it only computes the number's
  177. length in hexadecimal digits. If the string starts with '\-', the
  178. number is negative. \fIBN_dec2bn()\fR is the same using the decimal system.
  179. .PP
  180. \&\fIBN_print()\fR and \fIBN_print_fp()\fR write the hexadecimal encoding of \fBa\fR,
  181. with a leading '\-' for negative numbers, to the \fB\s-1BIO\s0\fR or \fB\s-1FILE\s0\fR
  182. \&\fBfp\fR.
  183. .PP
  184. \&\fIBN_bn2mpi()\fR and \fIBN_mpi2bn()\fR convert \fB\s-1BIGNUM\s0\fRs from and to a format
  185. that consists of the number's length in bytes represented as a 4\-byte
  186. big-endian number, and the number itself in big-endian format, where
  187. the most significant bit signals a negative number (the representation
  188. of numbers with the \s-1MSB\s0 set is prefixed with null byte).
  189. .PP
  190. \&\fIBN_bn2mpi()\fR stores the representation of \fBa\fR at \fBto\fR, where \fBto\fR
  191. must be large enough to hold the result. The size can be determined by
  192. calling BN_bn2mpi(\fBa\fR, \s-1NULL\s0).
  193. .PP
  194. \&\fIBN_mpi2bn()\fR converts the \fBlen\fR bytes long representation at \fBs\fR to
  195. a \fB\s-1BIGNUM\s0\fR and stores it at \fBret\fR, or in a newly allocated \fB\s-1BIGNUM\s0\fR
  196. if \fBret\fR is \s-1NULL.\s0
  197. .SH "RETURN VALUES"
  198. .IX Header "RETURN VALUES"
  199. \&\fIBN_bn2bin()\fR returns the length of the big-endian number placed at \fBto\fR.
  200. \&\fIBN_bin2bn()\fR returns the \fB\s-1BIGNUM\s0\fR, \s-1NULL\s0 on error.
  201. .PP
  202. \&\fIBN_bn2hex()\fR and \fIBN_bn2dec()\fR return a null-terminated string, or \s-1NULL\s0
  203. on error. \fIBN_hex2bn()\fR and \fIBN_dec2bn()\fR return the number's length in
  204. hexadecimal or decimal digits, and 0 on error.
  205. .PP
  206. \&\fIBN_print_fp()\fR and \fIBN_print()\fR return 1 on success, 0 on write errors.
  207. .PP
  208. \&\fIBN_bn2mpi()\fR returns the length of the representation. \fIBN_mpi2bn()\fR
  209. returns the \fB\s-1BIGNUM\s0\fR, and \s-1NULL\s0 on error.
  210. .PP
  211. The error codes can be obtained by \fIERR_get_error\fR\|(3).
  212. .SH "SEE ALSO"
  213. .IX Header "SEE ALSO"
  214. \&\fIbn\fR\|(3), \fIERR_get_error\fR\|(3), \fIBN_zero\fR\|(3),
  215. \&\fIASN1_INTEGER_to_BN\fR\|(3),
  216. \&\fIBN_num_bytes\fR\|(3)
  217. .SH "HISTORY"
  218. .IX Header "HISTORY"
  219. \&\fIBN_bn2bin()\fR, \fIBN_bin2bn()\fR, \fIBN_print_fp()\fR and \fIBN_print()\fR are available
  220. in all versions of SSLeay and OpenSSL.
  221. .PP
  222. \&\fIBN_bn2hex()\fR, \fIBN_bn2dec()\fR, \fIBN_hex2bn()\fR, \fIBN_dec2bn()\fR, \fIBN_bn2mpi()\fR and
  223. \&\fIBN_mpi2bn()\fR were added in SSLeay 0.9.0.