BN_mpi2bn (3)

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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

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

and places it in ret. If ret is a new 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

and stores it in **bn. If *bn is a new is created. If bn is 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

or fp.

BN_bn2mpi() and BN_mpi2bn() convert

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 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,

).

BN_mpi2bn() converts the len bytes long representation at s to a

and stores it at ret, or in a newly allocated if ret is

RETURN VALUES

BN_bn2bin() returns the length of the big-endian number placed at to. BN_bin2bn() returns the , on error.

BN_bn2hex() and BN_bn2dec() return a null-terminated string, or

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

, and on error.

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

SEE ALSO

bn(3), ERR_get_error(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.