OPENSSL_HEXCHAR2INT(3ossl)

🌸 NAME 🌸

Okay bestie, welcome to OPENSSL_HEXCHAR2INT(3ossl) — the hex glow-up page 💅. This is the whole little fam of hex encoding/decoding functions: OPENSSL_hexchar2int, OPENSSL_hexstr2buf_ex, OPENSSL_hexstr2buf, OPENSSL_buf2hexstr_ex, and OPENSSL_buf2hexstr. Hex characters in, bytes out, bytes in, hex characters out — it's giving ✨conversion✨.

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✨ 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, const char sep);
unsigned char *OPENSSL_hexstr2buf(const char *str, long *len);
int OPENSSL_buf2hexstr_ex(char *str, size_t str_n, size_t *strlength,
                          const unsigned char *buf, long buflen,
                          const char sep);
char *OPENSSL_buf2hexstr(const unsigned char *buf, long buflen);

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🦋 DESCRIPTION 🦋

💜 OPENSSL_hexchar2int()

Converts a hexadecimal character to its numeric equivalent. One char in, its number out. Tiny, iconic, does exactly what it says 🎀.

🎀 OPENSSL_hexstr2buf_ex()

Decodes the hex string str and places the resulting string of bytes in the given buf. The character sep is the separator between the bytes — setting this to '\0' means there is no separator, like, at all 🫶. buf_n gives the size of the buffer. If buflen is not NULL, it gets filled in with the result length. Want to know how big the result is gonna be? Call this function with NULL for buf first — vibe check the size, then commit 💅.

Also, lowkey important: colons between two-character hex "bytes" are accepted and ignored. But an odd number of hex digits? That's an error, no cap 😭.

🌈 OPENSSL_hexstr2buf()

Does the same thing as OPENSSL_hexstr2buf_ex(), but it allocates the space for the result and returns the result. It uses a default separator of ':'. The memory is allocated by calling OPENSSL_malloc() and should be released by calling OPENSSL_free() — yes bestie, you gotta free it yourself, that's the whole deal 🔥.

🦋 OPENSSL_buf2hexstr_ex()

Encodes the contents of the given buf with length buflen and places the resulting hexadecimal character string in the given str. The character sep is the separator between the bytes — setting this to '\0' means there is no separator ✨. str_n gives the size of the string buffer. If strlength is not NULL, it gets filled in with the result length. And to find out how large the result will be, call this function with NULL for str — same size-preview trick as above, iykyk 💖.

⭐ OPENSSL_buf2hexstr()

Does the same thing as OPENSSL_buf2hexstr_ex(), but it allocates the space for the result and returns the result. Default separator? ':', obviously 🎀. The memory is allocated by calling OPENSSL_malloc() and should be released by calling OPENSSL_free() — don't forget, or that's a leak and you'll cry 🫶.

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👑 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.

Quick vibe check: 1/0 for the _ex girlies, pointers (or NULL) for the allocating ones, and -1 when the single-char decoder is like "nope, not a hex digit." 🙈

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📜 COPYRIGHT 📜

Copyright 2016-2022 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 <https://www.openssl.org/source/license.html>.

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And that's the page, bestie 💖✨ This was OpenSSL 3.5.6, dated 2026-04-07, signing off as OPENSSL_HEXCHAR2INT(3ossl) — slay, stay hexed, and free your buffers 🎀🦋💅