1=pod 2 3=head1 NAME 4 5BN_bn2binpad, 6BN_bn2bin, BN_bin2bn, BN_bn2lebinpad, BN_lebin2bn, 7BN_bn2nativepad, BN_native2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, 8BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions 9 10=head1 SYNOPSIS 11 12 #include <openssl/bn.h> 13 14 int BN_bn2bin(const BIGNUM *a, unsigned char *to); 15 int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen); 16 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret); 17 18 int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen); 19 BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret); 20 21 int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen); 22 BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret); 23 24 char *BN_bn2hex(const BIGNUM *a); 25 char *BN_bn2dec(const BIGNUM *a); 26 int BN_hex2bn(BIGNUM **a, const char *str); 27 int BN_dec2bn(BIGNUM **a, const char *str); 28 29 int BN_print(BIO *fp, const BIGNUM *a); 30 int BN_print_fp(FILE *fp, const BIGNUM *a); 31 32 int BN_bn2mpi(const BIGNUM *a, unsigned char *to); 33 BIGNUM *BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret); 34 35=head1 DESCRIPTION 36 37BN_bn2bin() converts the absolute value of B<a> into big-endian form 38and stores it at B<to>. B<to> must point to BN_num_bytes(B<a>) bytes of 39memory. 40 41BN_bn2binpad() also converts the absolute value of B<a> into big-endian form 42and stores it at B<to>. B<tolen> indicates the length of the output buffer 43B<to>. The result is padded with zeros if necessary. If B<tolen> is less than 44BN_num_bytes(B<a>) an error is returned. 45 46BN_bin2bn() converts the positive integer in big-endian form of length 47B<len> at B<s> into a B<BIGNUM> and places it in B<ret>. If B<ret> is 48NULL, a new B<BIGNUM> is created. 49 50BN_bn2lebinpad() and BN_lebin2bn() are identical to BN_bn2binpad() and 51BN_bin2bn() except the buffer is in little-endian format. 52 53BN_bn2nativepad() and BN_native2bn() are identical to BN_bn2binpad() and 54BN_bin2bn() except the buffer is in native format, i.e. most significant 55byte first on big-endian platforms, and least significant byte first on 56little-endian platforms. 57 58BN_bn2hex() and BN_bn2dec() return printable strings containing the 59hexadecimal and decimal encoding of B<a> respectively. For negative 60numbers, the string is prefaced with a leading '-'. The string must be 61freed later using OPENSSL_free(). 62 63BN_hex2bn() takes as many characters as possible from the string B<str>, 64including the leading character '-' which means negative, to form a valid 65hexadecimal number representation and converts them to a B<BIGNUM> and 66stores it in **B<a>. If *B<a> is NULL, a new B<BIGNUM> is created. If 67B<a> is NULL, it only computes the length of valid representation. 68A "negative zero" is converted to zero. 69BN_dec2bn() is the same using the decimal system. 70 71BN_print() and BN_print_fp() write the hexadecimal encoding of B<a>, 72with a leading '-' for negative numbers, to the B<BIO> or B<FILE> 73B<fp>. 74 75BN_bn2mpi() and BN_mpi2bn() convert B<BIGNUM>s from and to a format 76that consists of the number's length in bytes represented as a 4-byte 77big-endian number, and the number itself in big-endian format, where 78the most significant bit signals a negative number (the representation 79of numbers with the MSB set is prefixed with null byte). 80 81BN_bn2mpi() stores the representation of B<a> at B<to>, where B<to> 82must be large enough to hold the result. The size can be determined by 83calling BN_bn2mpi(B<a>, NULL). 84 85BN_mpi2bn() converts the B<len> bytes long representation at B<s> to 86a B<BIGNUM> and stores it at B<ret>, or in a newly allocated B<BIGNUM> 87if B<ret> is NULL. 88 89=head1 RETURN VALUES 90 91BN_bn2bin() returns the length of the big-endian number placed at B<to>. 92BN_bin2bn() returns the B<BIGNUM>, NULL on error. 93 94BN_bn2binpad(), BN_bn2lebinpad(), and BN_bn2nativepad() return the number of bytes written or -1 if the supplied 95buffer is too small. 96 97BN_bn2hex() and BN_bn2dec() return a NUL-terminated string, or NULL 98on error. BN_hex2bn() and BN_dec2bn() return the number of characters 99used in parsing, or 0 on error, in which 100case no new B<BIGNUM> will be created. 101 102BN_print_fp() and BN_print() return 1 on success, 0 on write errors. 103 104BN_bn2mpi() returns the length of the representation. BN_mpi2bn() 105returns the B<BIGNUM>, and NULL on error. 106 107The error codes can be obtained by L<ERR_get_error(3)>. 108 109=head1 SEE ALSO 110 111L<ERR_get_error(3)>, L<BN_zero(3)>, 112L<ASN1_INTEGER_to_BN(3)>, 113L<BN_num_bytes(3)> 114 115=head1 COPYRIGHT 116 117Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. 118 119Licensed under the Apache License 2.0 (the "License"). You may not use 120this file except in compliance with the License. You can obtain a copy 121in the file LICENSE in the source distribution or at 122L<https://www.openssl.org/source/license.html>. 123 124=cut 125