BN_bn2bin(3)BN_bn2bin(3)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
The BN_bn2bin() function converts the absolute value of a into big-
endian form and stores it at to. The to value must point to
BN_num_bytes(a) bytes of memory.
The BN_bin2bn() function 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.
The BN_bn2hex() and BN_bn2dec() functions return printable strings con‐
taining 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 cre‐
ated. If bn is NULL, it only computes the number's length in hexadeci‐
mal digits. If the string starts with '-', the number is negative.
BN_dec2bn() is the same using the decimal system.
The BN_print() and BN_print_fp() functions write the hexadecimal encod‐
ing of a, with a leading '-' for negative numbers, to the BIO or FILE
fp.
The BN_bn2mpi() and BN_mpi2bn() functions 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 represen‐
tation of numbers with the MSB set is prefixed with null byte).
The BN_bn2mpi() function 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).
The BN_mpi2bn() function 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
The BN_bn2bin() function returns the length of the big-endian number
placed at to. The BN_bin2bn() function returns the BIGNUM, NULL on
error.
The BN_bn2hex() and BN_bn2dec() functions return a null-terminated
string, or NULL on error. The BN_hex2bn() and BN_dec2bn() functions
return the number's length in hexadecimal or decimal digits, and 0 on
error.
The BN_print_fp() and BN_print() functions return 1 on success, 0 on
write errors.
The BN_bn2mpi() function returns the length of the representation. The
BN_mpi2bn() function returns the BIGNUM, and NULL on error.
The error codes can be obtained by using the ERR_get_error() function.
HISTORY
The BN_bn2bin(), BN_bin2bn(), BN_print_fp(), and BN_print() functions
are available in all versions of SSLeay and OpenSSL.
The BN_bn2hex(), BN_bn2dec(), BN_hex2bn(), BN_dec2bn(), BN_bn2mpi(),
and BN_mpi2bn() functions were added in SSLeay 0.9.0.
SEE ALSO
Functions: bn(3), err(3), BN_zero(3), ASN1_INTEGER_to_BN(3),
BN_num_bytes(3)BN_bn2bin(3)