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=head1 NAME

OPENSSL_hexchar2int,
OPENSSL_hexstr2buf_ex, OPENSSL_hexstr2buf,
OPENSSL_buf2hexstr_ex, OPENSSL_buf2hexstr
- Hex encoding and decoding functions

=head1 SYNOPSIS

 #include <openssl/crypto.h>

 int OPENSSL_hexchar2int(unsigned char c);
 int OPENSSL_hexstr2buf_ex(unsigned char *buf, size_t buf_n, long *buflen,
                           const char *str);
 unsigned char *OPENSSL_hexstr2buf(const char *str, long *len);
 int OPENSSL_buf2hexstr_ex(char *str, size_t str_n, size_t *strlen,
                           const unsigned char *buf, long buflen);
 char *OPENSSL_buf2hexstr(const unsigned char *buf, long buflen);

=head1 DESCRIPTION

OPENSSL_hexchar2int() converts a hexadecimal character to its numeric
equivalent.

OPENSSL_hexstr2buf_ex() decodes the hex string B<str> and places the
resulting string of bytes in the given I<buf>.
I<buf_n> gives the size of the buffer.
If I<buflen> is not NULL, it is filled in with the result length.
To find out how large the result will be, call this function with NULL
for I<buf>.
Colons between two-character hex "bytes" are accepted and ignored.
An odd number of hex digits is an error.

OPENSSL_hexstr2buf() does the same thing as OPENSSL_hexstr2buf_ex(),
but allocates the space for the result, and returns the result.
The memory is allocated by calling OPENSSL_malloc() and should be
released by calling OPENSSL_free().

OPENSSL_buf2hexstr_ex() encodes the contents of the given I<buf> with
length I<buflen> and places the resulting hexadecimal character string
in the given I<str>.
I<str_n> gives the size of the of the string buffer.
If I<strlen> is not NULL, it is filled in with the result length.
To find out how large the result will be, call this function with NULL
for I<str>.

OPENSSL_buf2hexstr() does the same thing as OPENSSL_buf2hexstr_ex(),
but allocates the space for the result, and returns the result.
The memory is allocated by calling OPENSSL_malloc() and should be
released by calling OPENSSL_free().

=head1 RETURN VALUES

OPENSSL_hexchar2int returns the value of a decoded hex character,
or -1 on error.

OPENSSL_buf2hexstr() and OPENSSL_hexstr2buf()
return a pointer to allocated memory, or NULL on error.

OPENSSL_buf2hexstr_ex() and OPENSSL_hexstr2buf_ex() return 1 on
success, or 0 on error.

=head1 COPYRIGHT

Copyright 2016-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.

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