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BN_bn2bin(3) OpenSSL BN_bn2bin(3)## 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 ofainto big-endian form and stores it atto.tomust point to BN_num_bytes(a) bytes of memory.BN_bin2bn()converts the positive integer in big-endian form of lengthlenatsinto aBIGNUMand places it inret. Ifretis NULL, a newBIGNUMis created.BN_bn2hex()andBN_bn2dec()return printable strings containing the hexadecimal and decimal encoding ofarespectively. For negative numbers, the string is prefaced with a leading '-'. The string must be freed later usingOPENSSL_free().BN_hex2bn()converts the stringstrcontaining a hexadecimal number to aBIGNUMand stores it in **bn. If *bnis NULL, a newBIGNUMis created. Ifbnis 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()andBN_print_fp()write the hexadecimal encoding ofa, with a leading '-' for negative numbers, to theBIOorFILEfp.BN_bn2mpi()andBN_mpi2bn()convertBIGNUMs 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 ofaatto, wheretomust be large enough to hold the result. The size can be determined by calling BN_bn2mpi(a, NULL).BN_mpi2bn()converts thelenbytes long representation atsto aBIGNUMand stores it atret, or in a newly allocatedBIGNUMifretis NULL.## RETURN VALUES

BN_bn2bin()returns the length of the big-endian number placed atto.BN_bin2bn()returns theBIGNUM, NULL on error.BN_bn2hex()andBN_bn2dec()return a null-terminated string, or NULL on error.BN_hex2bn()andBN_dec2bn()return the number's length in hexadecimal or decimal digits, and 0 on error.BN_print_fp()andBN_print()return 1 on success, 0 on write errors.BN_bn2mpi()returns the length of the representation.BN_mpi2bn()returns theBIGNUM, and NULL on error. The error codes can be obtained byERR_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()andBN_print()are available in all versions of SSLeay and OpenSSL.BN_bn2hex(),BN_bn2dec(),BN_hex2bn(),BN_dec2bn(),BN_bn2mpi()andBN_mpi2bn()were added in SSLeay 0.9.0. 1.0.2h 2016-05-03 BN_bn2bin(3)

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