=pod
=head1 NAME
BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn,
BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions
=head1 SYNOPSIS
#include
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);
=head1 DESCRIPTION
BN_bn2bin() converts the absolute value of B into big-endian form
and stores it at B. B must point to BN_num_bytes(B) bytes of
memory.
BN_bin2bn() converts the positive integer in big-endian form of length
B at B~~ into a B and places it in B. If B is
NULL, a new B is created.
BN_bn2hex() and BN_bn2dec() return printable strings containing the
hexadecimal and decimal encoding of B~~~~ 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 B containing a hexadecimal number
to a B and stores it in **B. If *B is NULL, a new
B is created. If B is NULL, it only computes the number's
length in hexadecimal digits. If the string starts with '-', the
number is negative.
A "negative zero" is converted to zero.
BN_dec2bn() is the same using the decimal system.
BN_print() and BN_print_fp() write the hexadecimal encoding of B,
with a leading '-' for negative numbers, to the B or B
B.
BN_bn2mpi() and BN_mpi2bn() convert Bs 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 B at B, where B
must be large enough to hold the result. The size can be determined by
calling BN_bn2mpi(B, NULL).
BN_mpi2bn() converts the B bytes long representation at B~~~~ to
a B and stores it at B, or in a newly allocated B
if B is NULL.
=head1 RETURN VALUES
BN_bn2bin() returns the length of the big-endian number placed at B.
BN_bin2bn() returns the B, 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 of characters
used in parsing, or 0 on error, in which
case no new B will be 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 B, and NULL on error.
The error codes can be obtained by L.
=head1 SEE ALSO
L, L, L,
L,
L
=head1 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.
=cut
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