1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
.\" $OpenBSD: BN_new.3,v 1.31 2023/07/26 20:08:59 tb Exp $
.\" full merge up to: OpenSSL man3/BN_new 2457c19d Mar 6 08:43:36 2004 +0000
.\" selective merge up to: man3/BN_new 681acb31 Sep 29 13:10:34 2017 +0200
.\" full merge up to: OpenSSL man7/bn 05ea606a May 20 20:52:46 2016 -0400
.\"
.\" This file was written by Ulf Moeller <ulf@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: July 26 2023 $
.Dt BN_NEW 3
.Os
.Sh NAME
.Nm BN_new ,
.Nm BN_clear ,
.Nm BN_free ,
.Nm BN_clear_free
.Nd allocate and free BIGNUMs
.Sh SYNOPSIS
.In openssl/bn.h
.Ft BIGNUM *
.Fo BN_new
.Fa void
.Fc
.Ft void
.Fo BN_clear
.Fa "BIGNUM *a"
.Fc
.Ft void
.Fo BN_free
.Fa "BIGNUM *a"
.Fc
.Ft void
.Fo BN_clear_free
.Fa "BIGNUM *a"
.Fc
.Sh DESCRIPTION
The BN library performs arithmetic operations on integers of arbitrary
size.
It was written for use in public key cryptography, such as RSA and
Diffie-Hellman.
.Pp
It uses dynamic memory allocation for storing its data structures.
That means that there is no limit on the size of the numbers manipulated
by these functions, but return values must always be checked in case a
memory allocation error has occurred.
.Pp
The basic object in this library is a
.Vt BIGNUM .
It is used to hold a single large integer.
This type should be considered opaque and fields should not be modified
or accessed directly.
.Pp
.Fn BN_new
allocates and initializes a
.Vt BIGNUM
structure, in particular setting the value to zero and the flags to
.Dv BN_FLG_MALLOCED .
The security-relevant flag
.Dv BN_FLG_CONSTTIME
is not set by default.
.Pp
.Fn BN_clear
is used to destroy sensitive data such as keys when they are no longer
needed.
It erases the memory used by
.Fa a
and sets it to the value 0.
.Pp
.Fn BN_free
frees the components of the
.Vt BIGNUM
and, if it was created by
.Fn BN_new ,
also the structure itself.
.Fn BN_clear_free
additionally overwrites the data before the memory is returned to the
system.
If
.Fa a
is a
.Dv NULL
pointer, no action occurs.
.Sh RETURN VALUES
.Fn BN_new
returns a pointer to the
.Vt BIGNUM .
If the allocation fails, it returns
.Dv NULL
and sets an error code that can be obtained by
.Xr ERR_get_error 3 .
.Sh SEE ALSO
.Xr BN_add 3 ,
.Xr BN_add_word 3 ,
.Xr BN_bn2bin 3 ,
.Xr BN_cmp 3 ,
.Xr BN_copy 3 ,
.Xr BN_CTX_new 3 ,
.Xr BN_CTX_start 3 ,
.Xr BN_generate_prime 3 ,
.Xr BN_get_rfc3526_prime_8192 3 ,
.Xr BN_kronecker 3 ,
.Xr BN_mod_inverse 3 ,
.Xr BN_mod_mul_montgomery 3 ,
.Xr BN_mod_sqrt 3 ,
.Xr BN_num_bytes 3 ,
.Xr BN_rand 3 ,
.Xr BN_security_bits 3 ,
.Xr BN_set_bit 3 ,
.Xr BN_set_flags 3 ,
.Xr BN_set_negative 3 ,
.Xr BN_swap 3 ,
.Xr BN_zero 3 ,
.Xr crypto 3
.Sh HISTORY
.Fn BN_new ,
.Fn BN_clear ,
.Fn BN_free ,
and
.Fn BN_clear_free
first appeared in SSLeay 0.5.1 and have been available since
.Ox 2.4 .
|
