S2I_ASN1_IA5STRING(3SSL)

💖 S2I_ASN1_IA5STRING 💖

okay bestie, welcome to S2I_ASN1_IA5STRING(3SSL), the OpenSSL page where we flip objects back and forth between ~vibes~ and ~bytes~. it lives in the 3SSL manual, and honestly? it's giving translator energy. 🦋

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✨ NAME ✨

i2s_ASN1_IA5STRING, s2i_ASN1_IA5STRING, i2s_ASN1_INTEGER, s2i_ASN1_INTEGER, i2s_ASN1_OCTET_STRING, s2i_ASN1_OCTET_STRING, i2s_ASN1_ENUMERATED, i2s_ASN1_ENUMERATED_TABLE, i2s_ASN1_UTF8STRING, s2i_ASN1_UTF8STRING — the whole squad that converts objects from/to ASN.1/string representation. no cap. 💅

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🌈 SYNOPSIS 🌈

#include <openssl/x509v3.h>

char *i2s_ASN1_IA5STRING(X509V3_EXT_METHOD *method, ASN1_IA5STRING *ia5);
ASN1_IA5STRING *s2i_ASN1_IA5STRING(X509V3_EXT_METHOD *method,
                                  X509V3_CTX *ctx, const char *str);
char *i2s_ASN1_INTEGER(X509V3_EXT_METHOD *method, const ASN1_INTEGER *a);
ASN1_INTEGER *s2i_ASN1_INTEGER(X509V3_EXT_METHOD *method, const char *value);
char *i2s_ASN1_OCTET_STRING(X509V3_EXT_METHOD *method,
                           const ASN1_OCTET_STRING *oct);
ASN1_OCTET_STRING *s2i_ASN1_OCTET_STRING(X509V3_EXT_METHOD *method,
                                        X509V3_CTX *ctx, const char *str);
char *i2s_ASN1_ENUMERATED(X509V3_EXT_METHOD *method, const ASN1_ENUMERATED *a);
char *i2s_ASN1_ENUMERATED_TABLE(X509V3_EXT_METHOD *method,
                               const ASN1_ENUMERATED *e);

char *i2s_ASN1_UTF8STRING(X509V3_EXT_METHOD *method,
                          ASN1_UTF8STRING *utf8);
ASN1_UTF8STRING *s2i_ASN1_UTF8STRING(X509V3_EXT_METHOD *method,
                                     X509V3_CTX *ctx, const char *str);

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🎀 DESCRIPTION 🎀

so basically, these functions convert OpenSSL objects to and from their ASN.1/string representation. the whole point of them is X509v3 extensions — that's where they get their main character moment. ✨

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🧚 NOTES 🧚

okay so the letters i and s in i2s and s2i stand for "internal" (meaning: an internal C structure) and string, respectively. so i2s_ASN1_IA5STRING() converts from internal to string. internal → string, string → internal, we stay flipping. 🔁

here's the part where you need to pay attention though — it is the caller's responsibility to free the returned string. and in the i2s_ASN1_IA5STRING() function the string is copied, so the ownership of the original string stays with the caller. don't be out here freeing things you don't own. 🙈

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👑 RETURN VALUES 👑

• i2s_ASN1_IA5STRING() — returns the pointer to a IA5 string, or NULL if an error occurs.
• s2i_ASN1_IA5STRING() — return a valid ASN1_IA5STRING structure, or NULL if an error occurs.
• i2s_ASN1_INTEGER() — return a valid string, or NULL if an error occurs.
• s2i_ASN1_INTEGER() — returns the pointer to a ASN1_INTEGER structure, or NULL if an error occurs.
• i2s_ASN1_OCTET_STRING() — returns the pointer to a OCTET_STRING string, or NULL if an error occurs.
• s2i_ASN1_OCTET_STRING() — return a valid ASN1_OCTET_STRING structure, or NULL if an error occurs.
• i2s_ASN1_ENUMERATED() — return a valid string, or NULL if an error occurs.
• s2i_ASN1_ENUMERATED() — returns the pointer to a ASN1_ENUMERATED structure, or NULL if an error occurs.
• s2i_ASN1_UTF8STRING() — return a valid ASN1_UTF8STRING structure, or NULL if an error occurs.
• i2s_ASN1_UTF8STRING() — returns the pointer to a UTF-8 string, or NULL if an error occurs.

bestie the recurring theme here is NULL means something went wrong. that's the vibe check failing. 😭

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🌸 HISTORY 🌸

i2s_ASN1_UTF8STRING() and s2i_ASN1_UTF8STRING() were made public in OpenSSL 3.0. they were lowkey private before that. now they're out here living their truth. 🫶

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💜 COPYRIGHT 💜

Copyright 2020-2021 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 whole page, bestie!! 💅✨ this was version 4.0.3, dated 2026-09-29, straight from OpenSSL — so the next time someone asks you how to convert ASN.1 objects to strings, you're gonna ate that question up. periodt. 🎀🦋💖