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BN_BN2BIN(3) Library Functions Manual BN_BN2BIN(3)

BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, BN_asc2bn, BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bnformat conversions

#include <openssl/bn.h>

BN_bn2bin(const BIGNUM *a, unsigned char *to);

BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);

char *
BN_bn2hex(const BIGNUM *a);

char *
BN_bn2dec(const BIGNUM *a);

BN_hex2bn(BIGNUM **a, const char *str);

BN_dec2bn(BIGNUM **a, const char *str);

BN_asc2bn(BIGNUM **a, const char *str);

BN_print(BIO *fp, const BIGNUM *a);

BN_print_fp(FILE *fp, const BIGNUM *a);

BN_bn2mpi(const BIGNUM *a, unsigned char *to);

BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret);

() converts the absolute value of a into big-endian form and stores it at to. to must point to (a) bytes of memory.

() 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.

() and () return printable strings containing the hexadecimal and decimal encoding of a respectively. For negative numbers, the string is prefaced with a leading minus sign. The string must be freed later using free(3).

() interprets str as a hexadecimal number. The string may start with a minus sign (‘-’). Conversion stops at the first byte that is not a hexadecimal digit. The number is converted to a BIGNUM and stored in *a. If *a is NULL, a new BIGNUM is created. If a is NULL, it only computes the number's length in hexadecimal digits. A "negative zero" is converted to zero. () is the same using the decimal system. () infers the number base from an optional prefix. If str starts with "0x" or "0X", it calls BN_hex2bn(), otherwise BN_dec2bn(). If the number is negative, the minus sign can be given before or after the prefix.

() and () write the hexadecimal encoding of a, with a leading minus sign for negative numbers, to the BIO or FILE fp.

() 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 a NUL byte).

() 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).

() 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, or NULL on error.

BN_bn2hex() and BN_bn2dec() return a NUL-terminated string, or NULL on error. BN_hex2bn() and BN_dec2bn() return the number's length in hexadecimal or decimal digits or 0 on error, in which case no new BIGNUM is created. BN_asc2bn() returns 1 on success or 0 on error, in which case no new BIGNUM is 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, or NULL on error.

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

BN_new(3), BN_num_bytes(3), BN_zero(3), ERR_get_error(3)

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.

January 25, 2017 OpenBSD-6.1