BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions

#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);

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 **BIGNUM**s 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.

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.

bn, ERR_get_error, BN_zero,
*ASN1_INTEGER_to_BN*,
BN_num_bytes

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.