.\" $NetBSD: libnetpgpbn.3,v 1.6 2018/04/04 21:39:35 sevan Exp $
.\"
.\" Copyright (c) 2010 Alistair Crooks <agc@NetBSD.org>
.\" All rights reserved.
.\"
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.Dd April 3, 2018
.Dt LIBNETPGPBN 3
.Os
.Sh NAME
.Nm libnetpgpbn
.Nd BIGNUM library of multi-precision integers
.Sh LIBRARY
.Lb libnetpgpbn
.Sh SYNOPSIS
.In netpgp/bn.h
.Ft BIGNUM *
.Fo BN_new
.Fa "void"
.Fc
.Ft BIGNUM *
.Fo BN_dup
.Fa "const BIGNUM *orig"
.Fc
.Ft int
.Fo BN_copy
.Fa "BIGNUM *to" "const BIGNUM *from"
.Fc
.Ft void
.Fo BN_swap
.Fa "BIGNUM *a" "BIGNUM *b"
.Fc
.Pp
.Ft void
.Fo BN_init
.Fa "BIGNUM *bn"
.Fc
.Ft void
.Fo BN_free
.Fa "BIGNUM *bn"
.Fc
.Ft void
.Fo BN_clear
.Fa "BIGNUM *bn"
.Fc
.Ft void
.Fo BN_clear_free
.Fa "BIGNUM *bn"
.Fc
.Pp
.Ft void
.Fo BN_clear_free
.Fa "BIGNUM *bn"
.Fc
.Pp
.Ft int
.Fo BN_cmp
.Fa "BIGNUM *lhs" "BIGNUM *rhs"
.Fc
.Ft int
.Fo BN_is_negative
.Fa "BIGNUM *bn"
.Fc
.Ft int
.Fo BN_is_zero
.Fa "BIGNUM *bn"
.Fc
.Ft int
.Fo BN_is_odd
.Fa "BIGNUM *bn"
.Fc
.Ft int
.Fo BN_is_even
.Fa "BIGNUM *bn"
.Fc
.Pp
.Ft BIGNUM *
.Fo BN_bin2bn
.Fa "const uint8_t *buf" "int size" "BIGNUM *bn"
.Fc
.Ft int
.Fo BN_bn2bin
.Fa "BIGNUM *bn" "uint8_t *buf"
.Fc
.Ft int
.Fo BN_bn2bin
.Fa "BIGNUM *bn" "uint8_t *buf"
.Fc
.Ft char *
.Fo BN_bn2hex
.Fa "const BIGNUM *bn"
.Fc
.Ft char *
.Fo BN_bn2dec
.Fa "const BIGNUM *bn"
.Fc
.Ft int
.Fo BN_hex2bn
.Fa "BIGNUM **bn" "const char *str"
.Fc
.Ft int
.Fo BN_dec2bn
.Fa "BIGNUM **bn" "const char *str"
.Fc
.Ft int
.Fo BN_print_fp
.Fa "FILE *fp" "const BIGNUM *bn"
.Fc
.Pp
.Ft int
.Fo BN_add
.Fa "BIGNUM *sum" "const BIGNUM *a" "const BIGNUM *b"
.Fc
.Ft int
.Fo BN_sub
.Fa "BIGNUM *sum" "const BIGNUM *a" "const BIGNUM *b"
.Fc
.Ft int
.Fo BN_mul
.Fa "BIGNUM *product" "const BIGNUM *a" "const BIGNUM *b" "BN_CTX *context"
.Fc
.Ft int
.Fo BN_div
.Fa "BIGNUM *quotient" "BIGNUM *remainder" "const BIGNUM *a" "const BIGNUM *b" "BN_CTX *context"
.Fc
.Pp
.Ft int
.Fo BN_lshift
.Fa "BIGNUM *result" "const BIGNUM *bn" "int n"
.Fc
.Ft int
.Fo BN_lshift1
.Fa "BIGNUM *result" "const BIGNUM *bn"
.Fc
.Ft int
.Fo BN_rshift
.Fa "BIGNUM *result" "const BIGNUM *bn" "int n"
.Fc
.Ft int
.Fo BN_rshift1
.Fa "BIGNUM *result" "const BIGNUM *bn"
.Fc
.Pp
.Ft int
.Fo BN_set_word
.Fa "BIGNUM *result" "unsigned long val"
.Fc
.Ft int
.Fo BN_set_negative
.Fa "BIGNUM *result" "int val"
.Fc
.Pp
.Ft int
.Fo BN_num_bytes
.Fa "const BIGNUM *bn"
.Fc
.Ft int
.Fo BN_num_bits
.Fa "const BIGNUM *bn"
.Fc
.Pp
.Ft int
.Fo BN_mod_exp
.Fa "BIGNUM *result" "BIGNUM *a" "BIGNUM *p" "BIGNUM *m" "BN_CTX *context"
.Fc
.Ft BIGNUM *
.Fo BN_mod_inverse
.Fa "BIGNUM *result" "BIGNUM *a" "BIGNUM *n" "BN_CTX *context"
.Fc
.Ft int
.Fo BN_mod_mul
.Fa "BIGNUM *result" "BIGNUM *a" "BIGNUM *b" "BIGNUM *m" "BN_CTX *context"
.Fc
.Ft int
.Fo BN_mod_sub
.Fa "BIGNUM *result" "BIGNUM *a" "BIGNUM *b" "BIGNUM *m" "BN_CTX *context"
.Fc
.Pp
.Ft BN_CTX *
.Fo BN_CTX_new
.Fa "void"
.Fc
.Ft BIGNUM *
.Fo BN_CTX_get
.Fa "BN_CTX *context"
.Fc
.Ft void
.Fo BN_CTX_start
.Fa "BN_CTX *context"
.Fc
.Ft void
.Fo BN_CTX_end
.Fa "BN_CTX *context"
.Fc
.Ft void
.Fo BN_CTX_init
.Fa "BN_CTX *context"
.Fc
.Ft void
.Fo BN_CTX_free
.Fa "BN_CTX *context"
.Fc
.Ft int
.Fo BN_rand
.Fa "BIGNUM *result" "int bits" "int top" "int bottom"
.Fc
.Ft int
.Fo BN_rand_range
.Fa "BIGNUM *result" "BIGNUM *range"
.Fc
.Ft int
.Fo BN_is_prime
.Fa "const BIGNUM *bn" "int checks" "void (*callback)(int int void)"
.Fa "BN_CTX *context" "void *callbackarg"
.Fc
.Pp
.Ft const BIGNUM *
.Fo BN_value_one
.Fa "void"
.Fc
.Ft int
.Fo BN_is_bit_set
.Fa "const BIGNUM *bn" "int n"
.Fc
.Sh DESCRIPTION
.Nm
emulates the API of the openssl
.Xr bn 3
library.
It is implemented using Tom St Denis's
.Dq libtommath
library.
.Sh EXAMPLES
The following code fragment will make a JSON object
out of the string
.Dq Hello <USERNAME>\en
in the
buffer called
.Va buf
where
.Dq USER
is the name of the user taken from the runtime environment.
The encoded text will be in an allocated buffer called
.Va s .
.Bd -literal -offset indent
mj_t atom;
char buf[BUFSIZ];
char *s;
int cc;

(void) memset(\*[Am]atom, 0x0, sizeof(atom));
cc = snprintf(buf, sizeof(buf), "Hello %s\en", getenv("USER"));
mj_create(\*[Am]atom, "string", buf, cc);
cc = mj_asprint(\*[Am]s, \*[Am]atom, MJ_JSON_ENCODE);
.Ed
.Pp
Next, the following example will take the (binary) text which has been encoded into
JSON and is in the buffer
.Va buf ,
such as in the previous example, and re-create the original text:
.Bd -literal -offset indent
int from, to, tok, cc;
char *s;
mj_t atom;

(void) memset(\*[Am]atom, 0x0, sizeof(atom));
from = to = tok = 0;
mj_parse(\*[Am]atom, buf, \*[Am]from, \*[Am]to, \*[Am]tok);
cc = mj_asprint(\*[Am]s, \*[Am]atom, MJ_HUMAN);
printf("%.*s", cc, s);
.Ed
.Pp
The
.Va s
pointer points to allocated storage with the original NUL-terminated string
in it.
.Sh SEE ALSO
.Xr bn 3
.Sh HISTORY
The
.Nm
library first appeared in
.Nx 7.0 .
.Sh AUTHORS
.An Alistair Crooks Aq Mt agc@NetBSD.org .