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 3-byte big-endian number, and the number
itself in big-endian format, where the most significant
bit signals a negative number (the representation of
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(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.
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