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Title "BN_BN2BIN 3"
BN_BN2BIN 3 "2020-09-22" "1.1.1h" "OpenSSL"
For nroff, turn off justification. Always turn off hyphenation; it makes
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"NAME"
BN_bn2binpad, BN_bn2bin, BN_bin2bn, BN_bn2lebinpad, BN_lebin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions
"SYNOPSIS"
Header "SYNOPSIS" .Vb 1 #include <openssl/bn.h> \& int BN_bn2bin(const BIGNUM *a, unsigned char *to); int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen); BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret); \& int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen); BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret); \& char *BN_bn2hex(const BIGNUM *a); char *BN_bn2dec(const BIGNUM *a); int BN_hex2bn(BIGNUM **a, const char *str); int BN_dec2bn(BIGNUM **a, const char *str); \& int BN_print(BIO *fp, const BIGNUM *a); int BN_print_fp(FILE *fp, const BIGNUM *a); \& int BN_bn2mpi(const BIGNUM *a, unsigned char *to); BIGNUM *BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret); .Ve
"DESCRIPTION"
Header "DESCRIPTION" \fBBN_bn2bin() converts the absolute value of a into big-endian form and stores it at to. to must point to BN_num_bytes(a) bytes of memory.

\fBBN_bn2binpad() also converts the absolute value of a into big-endian form and stores it at to. tolen indicates the length of the output buffer \fBto. The result is padded with zeros if necessary. If tolen is less than BN_num_bytes(a) an error is returned.

\fBBN_bin2bn() converts the positive integer in big-endian form of length \fBlen at s into a \s-1BIGNUM\s0 and places it in ret. If ret is \s-1NULL,\s0 a new \s-1BIGNUM\s0 is created.

\fBBN_bn2lebinpad() and BN_lebin2bn() are identical to BN_bn2binpad() and \fBBN_bin2bn() except the buffer is in little-endian format.

\fBBN_bn2hex() and BN_bn2dec() return printable strings containing the hexadecimal and decimal encoding of a respectively. For negative numbers, the string is prefaced with a leading '-'. The string must be freed later using OPENSSL_free().

\fBBN_hex2bn() takes as many characters as possible from the string str, including the leading character '-' which means negative, to form a valid hexadecimal number representation and converts them to a \s-1BIGNUM\s0 and stores it in **a. If *a is \s-1NULL,\s0 a new \s-1BIGNUM\s0 is created. If \fBa is \s-1NULL,\s0 it only computes the length of valid representation. A \*(L"negative zero\*(R" is converted to zero. \fBBN_dec2bn() is the same using the decimal system.

\fBBN_print() and BN_print_fp() write the hexadecimal encoding of a, with a leading '-' for negative numbers, to the \s-1BIO\s0 or \s-1FILE\s0 \fBfp.

\fBBN_bn2mpi() and BN_mpi2bn() convert \s-1BIGNUM\s0s from and to a format that consists of the number's length in bytes represented as a 4-byte big-endian number, and the number itself in big-endian format, where the most significant bit signals a negative number (the representation of numbers with the \s-1MSB\s0 set is prefixed with null byte).

\fBBN_bn2mpi() stores the representation of a at to, where to must be large enough to hold the result. The size can be determined by calling BN_bn2mpi(a, \s-1NULL\s0).

\fBBN_mpi2bn() converts the len bytes long representation at s to a \s-1BIGNUM\s0 and stores it at ret, or in a newly allocated \s-1BIGNUM\s0 if ret is \s-1NULL.\s0

"RETURN VALUES"
Header "RETURN VALUES" \fBBN_bn2bin() returns the length of the big-endian number placed at to. \fBBN_bin2bn() returns the \s-1BIGNUM\s0, \s-1NULL\s0 on error.

\fBBN_bn2binpad() returns the number of bytes written or -1 if the supplied buffer is too small.

\fBBN_bn2hex() and BN_bn2dec() return a null-terminated string, or \s-1NULL\s0 on error. BN_hex2bn() and BN_dec2bn() return the number of characters used in parsing, or 0 on error, in which case no new \s-1BIGNUM\s0 will be created.

\fBBN_print_fp() and BN_print() return 1 on success, 0 on write errors.

\fBBN_bn2mpi() returns the length of the representation. BN_mpi2bn() returns the \s-1BIGNUM\s0, and \s-1NULL\s0 on error.

The error codes can be obtained by ERR_get_error\|(3).

"SEE ALSO"
Header "SEE ALSO" \fBERR_get_error\|(3), BN_zero\|(3), \fBASN1_INTEGER_to_BN\|(3), \fBBN_num_bytes\|(3)
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.