1BN_bn2bin(3)                        OpenSSL                       BN_bn2bin(3)
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NAME

6       BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn,
7       BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions
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SYNOPSIS

10        #include <openssl/bn.h>
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12        int BN_bn2bin(const BIGNUM *a, unsigned char *to);
13        BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
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15        char *BN_bn2hex(const BIGNUM *a);
16        char *BN_bn2dec(const BIGNUM *a);
17        int BN_hex2bn(BIGNUM **a, const char *str);
18        int BN_dec2bn(BIGNUM **a, const char *str);
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20        int BN_print(BIO *fp, const BIGNUM *a);
21        int BN_print_fp(FILE *fp, const BIGNUM *a);
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23        int BN_bn2mpi(const BIGNUM *a, unsigned char *to);
24        BIGNUM *BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret);
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DESCRIPTION

27       BN_bn2bin() converts the absolute value of a into big-endian form and
28       stores it at to. to must point to BN_num_bytes(a) bytes of memory.
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30       BN_bin2bn() converts the positive integer in big-endian form of length
31       len at s into a BIGNUM and places it in ret. If ret is NULL, a new
32       BIGNUM is created.
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34       BN_bn2hex() and BN_bn2dec() return printable strings containing the
35       hexadecimal and decimal encoding of a respectively. For negative num‐
36       bers, the string is prefaced with a leading '-'. The string must be
37       freed later using OPENSSL_free().
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39       BN_hex2bn() converts the string str containing a hexadecimal number to
40       a BIGNUM and stores it in **bn. If *bn is NULL, a new BIGNUM is cre‐
41       ated. If bn is NULL, it only computes the number's length in hexadeci‐
42       mal digits. If the string starts with '-', the number is negative.
43       BN_dec2bn() is the same using the decimal system.
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45       BN_print() and BN_print_fp() write the hexadecimal encoding of a, with
46       a leading '-' for negative numbers, to the BIO or FILE fp.
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48       BN_bn2mpi() and BN_mpi2bn() convert BIGNUMs from and to a format that
49       consists of the number's length in bytes represented as a 4-byte big-
50       endian number, and the number itself in big-endian format, where the
51       most significant bit signals a negative number (the representation of
52       numbers with the MSB set is prefixed with null byte).
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54       BN_bn2mpi() stores the representation of a at to, where to must be
55       large enough to hold the result. The size can be determined by calling
56       BN_bn2mpi(a, NULL).
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58       BN_mpi2bn() converts the len bytes long representation at s to a BIGNUM
59       and stores it at ret, or in a newly allocated BIGNUM if ret is NULL.
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RETURN VALUES

62       BN_bn2bin() returns the length of the big-endian number placed at to.
63       BN_bin2bn() returns the BIGNUM, NULL on error.
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65       BN_bn2hex() and BN_bn2dec() return a null-terminated string, or NULL on
66       error. BN_hex2bn() and BN_dec2bn() return the number's length in hexa‐
67       decimal or decimal digits, and 0 on error.
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69       BN_print_fp() and BN_print() return 1 on success, 0 on write errors.
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71       BN_bn2mpi() returns the length of the representation. BN_mpi2bn()
72       returns the BIGNUM, and NULL on error.
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74       The error codes can be obtained by ERR_get_error(3).
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SEE ALSO

77       bn(3), ERR_get_error(3), BN_zero(3), ASN1_INTEGER_to_BN(3),
78       BN_num_bytes(3)
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HISTORY

81       BN_bn2bin(), BN_bin2bn(), BN_print_fp() and BN_print() are available in
82       all versions of SSLeay and OpenSSL.
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84       BN_bn2hex(), BN_bn2dec(), BN_hex2bn(), BN_dec2bn(), BN_bn2mpi() and
85       BN_mpi2bn() were added in SSLeay 0.9.0.
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890.9.8b                            2002-09-25                      BN_bn2bin(3)
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