| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | BN_bn2binpad,
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| 6 | BN_bn2bin, BN_bin2bn, BN_bn2lebinpad, BN_lebin2bn, BN_bn2hex, BN_bn2dec,
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| 7 | BN_hex2bn, BN_dec2bn, BN_print, BN_print_fp, BN_bn2mpi,
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| 8 | BN_mpi2bn - format conversions
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| 9 |
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| 10 | =head1 SYNOPSIS
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| 11 |
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| 12 | #include <openssl/bn.h>
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| 13 |
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| 14 | int BN_bn2bin(const BIGNUM *a, unsigned char *to);
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| 15 | int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen);
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| 16 | BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
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| 17 |
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| 18 | int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen);
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| 19 | BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret);
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| 20 |
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| 21 | char *BN_bn2hex(const BIGNUM *a);
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| 22 | char *BN_bn2dec(const BIGNUM *a);
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| 23 | int BN_hex2bn(BIGNUM **a, const char *str);
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| 24 | int BN_dec2bn(BIGNUM **a, const char *str);
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| 25 |
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| 26 | int BN_print(BIO *fp, const BIGNUM *a);
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| 27 | int BN_print_fp(FILE *fp, const BIGNUM *a);
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| 28 |
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| 29 | int BN_bn2mpi(const BIGNUM *a, unsigned char *to);
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| 30 | BIGNUM *BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret);
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| 31 |
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| 32 | =head1 DESCRIPTION
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| 33 |
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| 34 | BN_bn2bin() converts the absolute value of B<a> into big-endian form
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| 35 | and stores it at B<to>. B<to> must point to BN_num_bytes(B<a>) bytes of
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| 36 | memory.
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| 37 |
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| 38 | BN_bn2binpad() also converts the absolute value of B<a> into big-endian form
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| 39 | and stores it at B<to>. B<tolen> indicates the length of the output buffer
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| 40 | B<to>. The result is padded with zeros if necessary. If B<tolen> is less than
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| 41 | BN_num_bytes(B<a>) an error is returned.
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| 42 |
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| 43 | BN_bin2bn() converts the positive integer in big-endian form of length
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| 44 | B<len> at B<s> into a B<BIGNUM> and places it in B<ret>. If B<ret> is
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| 45 | NULL, a new B<BIGNUM> is created.
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| 46 |
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| 47 | BN_bn2lebinpad() and BN_lebin2bn() are identical to BN_bn2binpad() and
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| 48 | BN_bin2bn() except the buffer is in little-endian format.
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| 49 |
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| 50 | BN_bn2hex() and BN_bn2dec() return printable strings containing the
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| 51 | hexadecimal and decimal encoding of B<a> respectively. For negative
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| 52 | numbers, the string is prefaced with a leading '-'. The string must be
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| 53 | freed later using OPENSSL_free().
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| 54 |
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| 55 | BN_hex2bn() takes as many characters as possible from the string B<str>,
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| 56 | including the leading character '-' which means negative, to form a valid
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| 57 | hexadecimal number representation and converts them to a B<BIGNUM> and
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| 58 | stores it in **B<a>. If *B<a> is NULL, a new B<BIGNUM> is created. If
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| 59 | B<a> is NULL, it only computes the length of valid representation.
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| 60 | A "negative zero" is converted to zero.
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| 61 | BN_dec2bn() is the same using the decimal system.
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| 62 |
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| 63 | BN_print() and BN_print_fp() write the hexadecimal encoding of B<a>,
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| 64 | with a leading '-' for negative numbers, to the B<BIO> or B<FILE>
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| 65 | B<fp>.
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| 66 |
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| 67 | BN_bn2mpi() and BN_mpi2bn() convert B<BIGNUM>s from and to a format
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| 68 | that consists of the number's length in bytes represented as a 4-byte
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| 69 | big-endian number, and the number itself in big-endian format, where
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| 70 | the most significant bit signals a negative number (the representation
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| 71 | of numbers with the MSB set is prefixed with null byte).
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| 72 |
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| 73 | BN_bn2mpi() stores the representation of B<a> at B<to>, where B<to>
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| 74 | must be large enough to hold the result. The size can be determined by
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| 75 | calling BN_bn2mpi(B<a>, NULL).
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| 76 |
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| 77 | BN_mpi2bn() converts the B<len> bytes long representation at B<s> to
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| 78 | a B<BIGNUM> and stores it at B<ret>, or in a newly allocated B<BIGNUM>
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| 79 | if B<ret> is NULL.
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| 80 |
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| 81 | =head1 RETURN VALUES
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| 82 |
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| 83 | BN_bn2bin() returns the length of the big-endian number placed at B<to>.
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| 84 | BN_bin2bn() returns the B<BIGNUM>, NULL on error.
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| 85 |
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| 86 | BN_bn2binpad() returns the number of bytes written or -1 if the supplied
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| 87 | buffer is too small.
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| 88 |
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| 89 | BN_bn2hex() and BN_bn2dec() return a null-terminated string, or NULL
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| 90 | on error. BN_hex2bn() and BN_dec2bn() return the number of characters
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| 91 | used in parsing, or 0 on error, in which
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| 92 | case no new B<BIGNUM> will be created.
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| 93 |
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| 94 | BN_print_fp() and BN_print() return 1 on success, 0 on write errors.
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| 95 |
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| 96 | BN_bn2mpi() returns the length of the representation. BN_mpi2bn()
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| 97 | returns the B<BIGNUM>, and NULL on error.
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| 98 |
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| 99 | The error codes can be obtained by L<ERR_get_error(3)>.
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| 100 |
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| 101 | =head1 SEE ALSO
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| 102 |
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| 103 | L<ERR_get_error(3)>, L<BN_zero(3)>,
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| 104 | L<ASN1_INTEGER_to_BN(3)>,
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| 105 | L<BN_num_bytes(3)>
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| 106 |
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| 107 | =head1 COPYRIGHT
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| 108 |
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| 109 | Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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| 110 |
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| 111 | Licensed under the OpenSSL license (the "License"). You may not use
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| 112 | this file except in compliance with the License. You can obtain a copy
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| 113 | in the file LICENSE in the source distribution or at
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| 114 | L<https://www.openssl.org/source/license.html>.
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| 115 |
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| 116 | =cut
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