NAME

       BN_bn2binpad, BN_bn2bin, BN_bin2bn, BN_bn2lebinpad, BN_lebin2bn, 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);
        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 **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_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 zeroes 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 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 '-'. The string must be freed
       later using OPENSSL_free().

       BN_hex2bn() takes as many characters as possible from the string str, including the leading character '-'
       which means negative, to form a valid hexadecimal number representation and converts them to a BIGNUM and
       stores it in **a. If *a is NULL, a new BIGNUM is created. If a is NULL, it only computes the length of
       valid representation.  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 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_bn2binpad() returns the number of bytes written or -1 if the supplied buffer is too small.

       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 BIGNUM
       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 BIGNUM, and NULL on error.

       The error codes can be obtained by ERR_get_error(3).

SEE ALSO

       ERR_get_error(3), BN_zero(3), ASN1_INTEGER_to_BN(3), BN_num_bytes(3)

COPYRIGHT

       Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use this file except in compliance with
       the License.  You can obtain a copy in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.