1=pod 2 3=head1 NAME 4 5BN_bn2binpad, BN_signed_bn2bin, BN_bn2bin, BN_bin2bn, BN_signed_bin2bn, 6BN_bn2lebinpad, BN_signed_bn2lebin, BN_lebin2bn, BN_signed_lebin2bn, 7BN_bn2nativepad, BN_signed_bn2native, BN_native2bn, BN_signed_native2bn, 8BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, 9BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions 10 11=head1 SYNOPSIS 12 13 #include <openssl/bn.h> 14 15 int BN_bn2bin(const BIGNUM *a, unsigned char *to); 16 int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen); 17 int BN_signed_bn2bin(const BIGNUM *a, unsigned char *to, int tolen); 18 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret); 19 BIGNUM *BN_signed_bin2bn(const unsigned char *s, int len, BIGNUM *ret); 20 21 int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen); 22 int BN_signed_bn2lebin(const BIGNUM *a, unsigned char *to, int tolen); 23 BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret); 24 BIGNUM *BN_signed_lebin2bn(const unsigned char *s, int len, BIGNUM *ret); 25 26 int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen); 27 int BN_signed_bn2native(const BIGNUM *a, unsigned char *to, int tolen); 28 BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret); 29 BIGNUM *BN_signed_native2bn(const unsigned char *s, int len, BIGNUM *ret); 30 31 char *BN_bn2hex(const BIGNUM *a); 32 char *BN_bn2dec(const BIGNUM *a); 33 int BN_hex2bn(BIGNUM **a, const char *str); 34 int BN_dec2bn(BIGNUM **a, const char *str); 35 36 int BN_print(BIO *fp, const BIGNUM *a); 37 int BN_print_fp(FILE *fp, const BIGNUM *a); 38 39 int BN_bn2mpi(const BIGNUM *a, unsigned char *to); 40 BIGNUM *BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret); 41 42=head1 DESCRIPTION 43 44BN_bn2bin() converts the absolute value of B<a> into big-endian form 45and stores it at B<to>. B<to> must point to BN_num_bytes(B<a>) bytes of 46memory. B<a> and B<to> B<MUST NOT> be NULL. 47 48BN_bn2binpad() also converts the absolute value of B<a> into big-endian form 49and stores it at B<to>. B<tolen> indicates the length of the output buffer 50B<to>. The result is padded with zeros if necessary. If B<tolen> is less than 51BN_num_bytes(B<a>) an error is returned. 52 53BN_signed_bn2bin() converts the value of B<a> into big-endian signed 2's 54complements form and stores it at B<to>. B<tolen> indicates the length of 55the output buffer B<to>. The result is signed extended (padded with 0x00 56for positive numbers or with 0xff for negative numbers) if necessary. 57If B<tolen> is smaller than the necessary size (which may be 58C<<BN_num_bytes(B<a>) + 1>>), an error is returned. 59 60BN_bin2bn() converts the positive integer in big-endian form of length 61B<len> at B<s> into a B<BIGNUM> and places it in B<ret>. If B<ret> is 62NULL, a new B<BIGNUM> is created. B<s> B<MUST NOT> be NULL. 63 64BN_signed_bin2bn() converts the integer in big-endian signed 2's complement 65form of length B<len> at B<s> into a B<BIGNUM> and places it in B<ret>. If 66B<ret> is NULL, a new B<BIGNUM> is created. 67 68BN_bn2lebinpad(), BN_signed_bn2lebin() and BN_lebin2bn() are identical to 69BN_bn2binpad(), BN_signed_bn2bin() and BN_bin2bn() except the buffer is in 70little-endian format. 71 72BN_bn2nativepad(), BN_signed_bn2native() and BN_native2bn() are identical 73to BN_bn2binpad(), BN_signed_bn2bin() and BN_bin2bn() except the buffer is 74in native format, i.e. most significant byte first on big-endian platforms, 75and least significant byte first on little-endian platforms. 76 77BN_bn2hex() and BN_bn2dec() return printable strings containing the 78hexadecimal and decimal encoding of B<a> respectively. For negative 79numbers, the string is prefaced with a leading '-'. The string must be 80freed later using OPENSSL_free(). 81 82BN_hex2bn() takes as many characters as possible from the string B<str>, 83including the leading character '-' which means negative, to form a valid 84hexadecimal number representation and converts them to a B<BIGNUM> and 85stores it in **B<a>. If *B<a> is NULL, a new B<BIGNUM> is created. If 86B<a> is NULL, it only computes the length of valid representation. 87A "negative zero" is converted to zero. 88BN_dec2bn() is the same using the decimal system. 89 90BN_print() and BN_print_fp() write the hexadecimal encoding of B<a>, 91with a leading '-' for negative numbers, to the B<BIO> or B<FILE> 92B<fp>. 93 94BN_bn2mpi() and BN_mpi2bn() convert B<BIGNUM>s from and to a format 95that consists of the number's length in bytes represented as a 4-byte 96big-endian number, and the number itself in big-endian format, where 97the most significant bit signals a negative number (the representation 98of numbers with the MSB set is prefixed with null byte). 99 100BN_bn2mpi() stores the representation of B<a> at B<to>, where B<to> 101must be large enough to hold the result. The size can be determined by 102calling BN_bn2mpi(B<a>, NULL). 103 104BN_mpi2bn() converts the B<len> bytes long representation at B<s> to 105a B<BIGNUM> and stores it at B<ret>, or in a newly allocated B<BIGNUM> 106if B<ret> is NULL. 107 108=head1 RETURN VALUES 109 110BN_bn2bin() returns the length of the big-endian number placed at B<to>. 111BN_bin2bn() returns the B<BIGNUM>, NULL on error. 112 113BN_bn2binpad(), BN_signed_bn2bin(), BN_bn2lebinpad(), BN_signed_bn2lebin(), 114BN_bn2nativepad(), and_signed BN_bn2native() return the number of bytes 115written or -1 if the supplied buffer is too small. 116 117BN_bn2hex() and BN_bn2dec() return a NUL-terminated string, or NULL 118on error. BN_hex2bn() and BN_dec2bn() return the number of characters 119used in parsing, or 0 on error, in which 120case no new B<BIGNUM> will be created. 121 122BN_print_fp() and BN_print() return 1 on success, 0 on write errors. 123 124BN_bn2mpi() returns the length of the representation. BN_mpi2bn() 125returns the B<BIGNUM>, and NULL on error. 126 127The error codes can be obtained by L<ERR_get_error(3)>. 128 129=head1 SEE ALSO 130 131L<ERR_get_error(3)>, L<BN_zero(3)>, 132L<ASN1_INTEGER_to_BN(3)>, 133L<BN_num_bytes(3)> 134 135=head1 HISTORY 136 137The functions BN_signed_bin2bn(), BN_signed_bn2bin(), BN_signed_lebin2bn(), 138BN_signed_bn2lebin(), BN_signed_native2bn(), BN_signed_bn2native() 139were added in OpenSSL 3.2. 140 141=head1 COPYRIGHT 142 143Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved. 144 145Licensed under the Apache License 2.0 (the "License"). You may not use 146this file except in compliance with the License. You can obtain a copy 147in the file LICENSE in the source distribution or at 148L<https://www.openssl.org/source/license.html>. 149 150=cut 151
