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Editing: BN_bn2bin.3
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn \- format conversions .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/bn.h> \& \& int BN_bn2bin(const BIGNUM *a, unsigned char *to); \& BIGNUM *BN_bin2bn(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 .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBBN_bn2bin()\fR converts the absolute value of \fBa\fR into big-endian form and stores it at \fBto\fR. \fBto\fR must point to BN_num_bytes(\fBa\fR) bytes of memory. .PP \&\fBBN_bin2bn()\fR converts the positive integer in big-endian form of length \&\fBlen\fR at \fBs\fR into a \fB\s-1BIGNUM\s0\fR and places it in \fBret\fR. If \fBret\fR is \&\s-1NULL,\s0 a new \fB\s-1BIGNUM\s0\fR is created. .PP \&\fBBN_bn2hex()\fR and \fBBN_bn2dec()\fR return printable strings containing the hexadecimal and decimal encoding of \fBa\fR respectively. For negative numbers, the string is prefaced with a leading '\-'. The string must be freed later using \fBOPENSSL_free()\fR. .PP \&\fBBN_hex2bn()\fR converts the string \fBstr\fR containing a hexadecimal number to a \fB\s-1BIGNUM\s0\fR and stores it in **\fBa\fR. If *\fBa\fR is \s-1NULL,\s0 a new \&\fB\s-1BIGNUM\s0\fR is created. If \fBa\fR is \s-1NULL,\s0 it only computes the number's length in hexadecimal digits. If the string starts with '\-', the number is negative. A \*(L"negative zero\*(R" is converted to zero. \&\fBBN_dec2bn()\fR is the same using the decimal system. .PP \&\fBBN_print()\fR and \fBBN_print_fp()\fR write the hexadecimal encoding of \fBa\fR, with a leading '\-' for negative numbers, to the \fB\s-1BIO\s0\fR or \fB\s-1FILE\s0\fR \&\fBfp\fR. .PP \&\fBBN_bn2mpi()\fR and \fBBN_mpi2bn()\fR convert \fB\s-1BIGNUM\s0\fRs 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). .PP \&\fBBN_bn2mpi()\fR stores the representation of \fBa\fR at \fBto\fR, where \fBto\fR must be large enough to hold the result. The size can be determined by calling BN_bn2mpi(\fBa\fR, \s-1NULL\s0). .PP \&\fBBN_mpi2bn()\fR converts the \fBlen\fR bytes long representation at \fBs\fR to a \fB\s-1BIGNUM\s0\fR and stores it at \fBret\fR, or in a newly allocated \fB\s-1BIGNUM\s0\fR if \fBret\fR is \s-1NULL.\s0 .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBBN_bn2bin()\fR returns the length of the big-endian number placed at \fBto\fR. \&\fBBN_bin2bn()\fR returns the \fB\s-1BIGNUM\s0\fR, \s-1NULL\s0 on error. .PP \&\fBBN_bn2hex()\fR and \fBBN_bn2dec()\fR return a null-terminated string, or \s-1NULL\s0 on error. \fBBN_hex2bn()\fR and \fBBN_dec2bn()\fR return the number of characters used in parsing, or 0 on error, in which case no new \fB\s-1BIGNUM\s0\fR will be created. .PP \&\fBBN_print_fp()\fR and \fBBN_print()\fR return 1 on success, 0 on write errors. .PP \&\fBBN_bn2mpi()\fR returns the length of the representation. \fBBN_mpi2bn()\fR returns the \fB\s-1BIGNUM\s0\fR, and \s-1NULL\s0 on error. .PP The error codes can be obtained by \fBERR_get_error\fR\|(3). .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBbn\fR\|(3), \fBERR_get_error\fR\|(3), \fBBN_zero\fR\|(3), \&\fBASN1_INTEGER_to_BN\fR\|(3), \&\fBBN_num_bytes\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" \&\fBBN_bn2bin()\fR, \fBBN_bin2bn()\fR, \fBBN_print_fp()\fR and \fBBN_print()\fR are available in all versions of SSLeay and OpenSSL. .PP \&\fBBN_bn2hex()\fR, \fBBN_bn2dec()\fR, \fBBN_hex2bn()\fR, \fBBN_dec2bn()\fR, \fBBN_bn2mpi()\fR and \&\fBBN_mpi2bn()\fR were added in SSLeay 0.9.0.
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