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
36       numbers, 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
41       created. If bn is NULL, it only computes the number's length in
42       hexadecimal digits. If the string starts with '-', the number is
43       negative.  A "negative zero" is converted to zero.  BN_dec2bn() is the
44       same using the decimal system.
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46       BN_print() and BN_print_fp() write the hexadecimal encoding of a, with
47       a leading '-' for negative numbers, to the BIO or FILE fp.
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49       BN_bn2mpi() and BN_mpi2bn() convert BIGNUMs from and to a format that
50       consists of the number's length in bytes represented as a 4-byte big-
51       endian number, and the number itself in big-endian format, where the
52       most significant bit signals a negative number (the representation of
53       numbers with the MSB set is prefixed with null byte).
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55       BN_bn2mpi() stores the representation of a at to, where to must be
56       large enough to hold the result. The size can be determined by calling
57       BN_bn2mpi(a, NULL).
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59       BN_mpi2bn() converts the len bytes long representation at s to a BIGNUM
60       and stores it at ret, or in a newly allocated BIGNUM if ret is NULL.
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RETURN VALUES

63       BN_bn2bin() returns the length of the big-endian number placed at to.
64       BN_bin2bn() returns the BIGNUM, NULL on error.
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66       BN_bn2hex() and BN_bn2dec() return a null-terminated string, or NULL on
67       error. BN_hex2bn() and BN_dec2bn() return the number of characters used
68       in parsing, or 0 on error, in which case no new BIGNUM will be created.
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70       BN_print_fp() and BN_print() return 1 on success, 0 on write errors.
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72       BN_bn2mpi() returns the length of the representation. BN_mpi2bn()
73       returns the BIGNUM, and NULL on error.
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75       The error codes can be obtained by ERR_get_error(3).
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SEE ALSO

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

82       BN_bn2bin(), BN_bin2bn(), BN_print_fp() and BN_print() are available in
83       all versions of SSLeay and OpenSSL.
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85       BN_bn2hex(), BN_bn2dec(), BN_hex2bn(), BN_dec2bn(), BN_bn2mpi() and
86       BN_mpi2bn() were added in SSLeay 0.9.0.
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901.0.2o                            2020-08-01                      BN_bn2bin(3)
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