NAME
BN_bn2bin,
BN_bn2binpad, BN_bin2bn,
BN_bn2lebinpad, BN_lebin2bn,
BN_bn2hex, BN_bn2dec,
BN_hex2bn, BN_dec2bn,
BN_asc2bn, BN_print,
BN_print_fp, BN_bn2mpi,
BN_mpi2bn —
format conversions
SYNOPSIS
#include
<openssl/bn.h>
int
BN_bn2bin(const BIGNUM *a,
unsigned char *to);
int
BN_bn2binpad(const BIGNUM *a,
unsigned char *to, int
tolen);
BIGNUM *
BN_bin2bn(const unsigned char
*s, int len, BIGNUM
*ret);
int
BN_bn2lebinpad(const BIGNUM *a,
unsigned char *to, int
tolen);
BIGNUM *
BN_lebin2bn(const unsigned char
*s, int len, BIGNUM
*ret);
char *
BN_bn2hex(const BIGNUM *a);
char *
BN_bn2dec(const BIGNUM *a);
int
BN_hex2bn(BIGNUM **ap,
const char *str);
int
BN_dec2bn(BIGNUM **ap,
const char *str);
int
BN_asc2bn(BIGNUM **ap,
const char *str);
int
BN_print(BIO *fp,
const BIGNUM *a);
int
BN_print_fp(FILE *fp,
const BIGNUM *a);
int
BN_bn2mpi(const BIGNUM *a,
unsigned char *to);
BIGNUM *
BN_mpi2bn(unsigned char *s,
int len, BIGNUM *ret);
DESCRIPTION
BN_bn2bin()
converts the absolute value of a into big-endian form
and stores it at to. to must
point to
BN_num_bytes(a)
bytes of memory.
BN_bn2binpad()
also converts the absolute value of a into big-endian
form and stores it at to. tolen
indicates the length of the output buffer *to. The
result is padded with zeros if necessary. If tolen is
less than
BN_num_bytes(a),
an error is returned.
BN_bin2bn()
converts the positive integer in big-endian form of length
len at s into a
BIGNUM and places it in ret. If
ret is NULL, a new
BIGNUM is created.
BN_bn2lebinpad()
and
BN_lebin2bn()
are identical to BN_bn2binpad() and
BN_bin2bn() except the buffer
*to is in little-endian format.
BN_bn2hex()
and
BN_bn2dec()
return printable strings containing the hexadecimal and decimal encoding of
a respectively. For negative numbers, the string is
prefaced with a leading minus sign. The string must be freed later using
free(3).
BN_hex2bn()
interprets str as a hexadecimal number. The string may
start with a minus sign (‘-’). Conversion stops at the first
byte that is not a hexadecimal digit. The number is converted to a
BIGNUM and stored in **ap. If
*ap is NULL, a new
BIGNUM is created. If ap is
NULL, it only computes the number's length in
hexadecimal digits, also counting the leading minus sign if there is one. A
"negative zero" is converted to zero.
BN_dec2bn()
is the same using the decimal system.
BN_asc2bn()
infers the number base from an optional prefix. If str
starts with "0x" or "0X", it calls
BN_hex2bn(), otherwise
BN_dec2bn(). If the number is negative, the minus
sign can be given before or after the prefix.
BN_print()
and
BN_print_fp()
write the hexadecimal encoding of a, with a leading
minus sign for negative numbers, to the BIO or
FILE fp.
BN_bn2mpi()
and BN_mpi2bn() convert
BIGNUMs from and to a format that consists of the
number's length in bytes represented as a 4-byte big-endian number, and the
number itself in big-endian format, where the most significant bit signals a
negative number (the representation of numbers with the MSB set is prefixed
with a NUL byte).
BN_bn2mpi()
stores the representation of a at
to, where *to must be large
enough to hold the result. The size can be determined by calling
BN_bn2mpi(a,
NULL).
BN_mpi2bn()
converts the len bytes long representation at
s to a BIGNUM and stores it at
ret, or in a newly allocated
BIGNUM if ret is
NULL.
RETURN VALUES
BN_bn2bin() returns the length of the
big-endian number placed at to.
BN_bn2binpad() and
BN_bn2lebinpad() return the number of bytes written
or -1 if the supplied buffer is too small.
BN_bin2bn() and
BN_lebin2bn() return the
BIGNUM, or NULL on error.
BN_bn2hex() and
BN_bn2dec() return a NUL-terminated string, or
NULL on error. BN_hex2bn()
and BN_dec2bn() return the number's length in
hexadecimal or decimal digits, also counting the leading minus sign if there
is one, or 0 on error, in which case no new BIGNUM is
created. BN_asc2bn() returns 1 on success or 0 on
error, in which case no new BIGNUM is created.
BN_print_fp() and
BN_print() return 1 on success, 0 on write
errors.
BN_bn2mpi() returns the length of the
representation. BN_mpi2bn() returns the
BIGNUM, or NULL on error.
The error codes can be obtained by ERR_get_error(3).
SEE ALSO
ASN1_INTEGER_to_BN(3), BN_new(3), BN_num_bytes(3), BN_zero(3)
HISTORY
BN_bn2bin(),
BN_bin2bn(), and BN_print()
first appeared in SSLeay 0.5.1. BN_print_fp() first
appeared in SSLeay 0.6.0. BN_bn2hex(),
BN_bn2dec(), BN_hex2bn(),
BN_dec2bn(), BN_bn2mpi(),
and BN_mpi2bn() first appeared in SSLeay 0.9.0. All
these functions have been available since OpenBSD
2.4.
BN_asc2bin() first appeared in OpenSSL
1.0.0 and has been available since OpenBSD 4.9.
BN_bn2binpad(),
BN_bn2lebinpad(), and
BN_lebin2bn() first appeared in OpenSSL 1.1.0 and
have been available since OpenBSD 7.0.