NAME
BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, 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);
BIGNUM
*BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
char
*BN_bn2hex(const BIGNUM *a);
char *BN_bn2dec(const BIGNUM
*a);
int BN_hex2bn(BIGNUM **a, const char *str);
int
BN_dec2bn(BIGNUM **a, 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_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_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 '-'.
The string must be freed later using OPENSSL_free().
BN_hex2bn() converts the string str containing
a hexadecimal number to a BIGNUM and stores
it in **bn. If *bn is
NULL, a new BIGNUM is created. If bn is
NULL, it only computes the number's length in hexadecimal digits.
If the string starts with '-', the number is negative. BN_dec2bn()
is the same using the decimal system.
BN_print() and BN_print_fp() write the hexadecimal encoding
of a, with a leading '-' 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
null 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_bin2bn() returns the BIGNUM, NULL
on error.
BN_bn2hex() and BN_bn2dec() return a null-terminated string,
or NULL on error. BN_hex2bn() and BN_dec2bn() return the number's
length in hexadecimal or decimal digits, and 0 on error.
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, and NULL on error.
The error codes can be obtained by ERR_get_error(3).
SEE ALSO
bn(3), ERR_get_error(3), BN_zero(3),
ASN1_INTEGER_to_BN(3), BN_num_bytes(3)
HISTORY
BN_bn2bin(), BN_bin2bn(), BN_print_fp() and BN_print() are
available in all versions of SSLeay and OpenSSL.
BN_bn2hex(), BN_bn2dec(), BN_hex2bn(), BN_dec2bn(), BN_bn2mpi()
and BN_mpi2bn() were added in SSLeay 0.9.0.
