diff options
| author | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:54:44 -0400 |
|---|---|---|
| committer | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:54:44 -0400 |
| commit | a9157ce950dfe2fc30795d43b9d79b9d1bffc48b (patch) | |
| tree | 9df484304b560466d145e662c1c254ff0e9ae0ba /static/openbsd/man3/BN_num_bytes.3 | |
| parent | 160aa82b2d39c46ad33723d7d909cb4972efbb03 (diff) | |
docs: Added All OpenBSD Manuals
Diffstat (limited to 'static/openbsd/man3/BN_num_bytes.3')
| -rw-r--r-- | static/openbsd/man3/BN_num_bytes.3 | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/static/openbsd/man3/BN_num_bytes.3 b/static/openbsd/man3/BN_num_bytes.3 new file mode 100644 index 00000000..608bb2eb --- /dev/null +++ b/static/openbsd/man3/BN_num_bytes.3 @@ -0,0 +1,176 @@ +.\" $OpenBSD: BN_num_bytes.3,v 1.10 2025/06/08 22:40:29 schwarze Exp $ +.\" full merge up to: OpenSSL 9e183d22 Mar 11 08:56:44 2017 -0500 +.\" +.\" This file is a derived work. +.\" The changes are covered by the following Copyright and license: +.\" +.\" Copyright (c) 2022 Ingo Schwarze <schwarze@openbsd.org> +.\" +.\" Permission to use, copy, modify, and distribute this software for any +.\" purpose with or without fee is hereby granted, provided that the above +.\" copyright notice and this permission notice appear in all copies. +.\" +.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR +.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF +.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +.\" +.\" The original file was written by Ulf Moeller <ulf@openssl.org> +.\" and Richard Levitte <levitte@openssl.org>. +.\" Copyright (c) 2000, 2004 The OpenSSL Project. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in +.\" the documentation and/or other materials provided with the +.\" distribution. +.\" +.\" 3. All advertising materials mentioning features or use of this +.\" software must display the following acknowledgment: +.\" "This product includes software developed by the OpenSSL Project +.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" +.\" +.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to +.\" endorse or promote products derived from this software without +.\" prior written permission. For written permission, please contact +.\" openssl-core@openssl.org. +.\" +.\" 5. Products derived from this software may not be called "OpenSSL" +.\" nor may "OpenSSL" appear in their names without prior written +.\" permission of the OpenSSL Project. +.\" +.\" 6. Redistributions of any form whatsoever must retain the following +.\" acknowledgment: +.\" "This product includes software developed by the OpenSSL Project +.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY +.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR +.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED +.\" OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.Dd $Mdocdate: June 8 2025 $ +.Dt BN_NUM_BYTES 3 +.Os +.Sh NAME +.Nm BN_num_bits_word , +.Nm BN_num_bits , +.Nm BN_num_bytes +.Nd get BIGNUM size +.Sh SYNOPSIS +.Lb libcrypto +.In openssl/bn.h +.Ft int +.Fo BN_num_bits_word +.Fa "BN_ULONG w" +.Fc +.Ft int +.Fo BN_num_bits +.Fa "const BIGNUM *a" +.Fc +.Ft int +.Fo BN_num_bytes +.Fa "const BIGNUM *a" +.Fc +.Sh DESCRIPTION +.Fn BN_num_bits_word +returns the number of significant bits in +.Fa w , +that is, the minimum number of digits needed to write +.Fa w +as a binary number. +Except for an argument of 0, this is +.Pp +.D1 floor(log2( Ns Fa w ) ) No + 1 . +.Pp +.Vt BN_ULONG +is a macro that expands to +.Vt unsigned long Pq = Vt uint64_t +on +.Dv _LP64 +platforms and +.Vt unsigned int Pq = Vt uint32_t +elsewhere. +.Pp +.Fn BN_num_bits +returns the number of significant bits in the value of the +.Fa "BIGNUM *a" , +following the same principle as +.Fn BN_num_bits_word . +.Pp +.Fn BN_num_bytes +is a macro that returns the number of significant bytes in +.Fa a , +i.e. the minimum number of bytes needed to store the value of +.Fa a , +that is, +.Fn BN_num_bits a +divided by eight and rounded up to the next integer number. +.Sh RETURN VALUES +.Fn BN_num_bits_word +returns the number of significant bits in +.Fa w +or 0 if +.Fa w +is 0. +The maximum return value that can occur is +.Dv BN_BITS2 , +which is 64 on +.Dv _LP64 +platforms and 32 elsewhere. +.Pp +.Fn BN_num_bits +returns the number of significant bits and +.Fn BN_num_bytes +the number of significant bytes in +.Fa a , +or 0 if the value of +.Fa a +is 0. +.Sh SEE ALSO +.Xr BN_new 3 , +.Xr BN_security_bits 3 , +.Xr DH_size 3 , +.Xr DSA_size 3 , +.Xr RSA_size 3 +.Sh HISTORY +.Fn BN_num_bytes +and +.Fn BN_num_bits +first appeared in SSLeay 0.5.1. +.Fn BN_num_bits_word +first appeared in SSLeay 0.5.2. +These functions have been available since +.Ox 2.4 . +.Sh CAVEATS +Some have tried using +.Fn BN_num_bits +on individual numbers in RSA keys, DH keys and DSA keys, and found that +they don't always come up with the number of bits they expected +(something like 512, 1024, 2048, ...). +This is because generating a number with some specific number of bits +doesn't always set the highest bits, thereby making the number of +.Em significant +bits a little smaller. +If you want to know the "key size" of such a key, use functions like +.Xr RSA_size 3 , +.Xr DH_size 3 , +and +.Xr DSA_size 3 . |
