asn1\_get\_tag\_der(3) libtasn1 asn1\_get\_tag\_der(3)

# [NAME](#NAME)

asn1\_get\_tag\_der - API function

# [SYNOPSIS](#SYNOPSIS)

**#include <libtasn1.h>**

**int asn1\_get\_tag\_der(const unsigned char * der, int der\_len, unsigned char * cls, int * len, unsigned long * tag);**

# [ARGUMENTS](#ARGUMENTS)

[const unsigned char * der](#const)

DER data to decode.

[int der\_len](#int)

Length of DER data to decode.

[unsigned char * cls](#unsigned)

Output variable containing decoded class.

[int * len](#int~2)

Output variable containing the length of the DER TAG data.

[unsigned long * tag](#unsigned~2)

Output variable containing the decoded tag (may be **NULL**).

# [DESCRIPTION](#DESCRIPTION)

Decode the class and TAG from DER code.

# [RETURNS](#RETURNS)

Returns **ASN1\_SUCCESS** on success, or an error.

# [COPYRIGHT](#COPYRIGHT)

Copyright © 2006-2025 Free Software Foundation, Inc..  
Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

# [SEE ALSO](#SEE_ALSO)

The full documentation for **libtasn1** is maintained as a Texinfo manual. If the **info** and **libtasn1** programs are properly installed at your site, the command

**info libtasn1**

should give you access to the complete manual. As an alternative you may obtain the manual from:

**https://www.gnu.org/software/libtasn1/manual/**

4.21.0 libtasn1

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Document: asn1_get_tag_der(3) from libtasn1 4.21.0-r8 (Chainguard OS)
Source: https://gitlab.com/gnutls/libtasn1