---
name: "asn1_get_tag_der"
section: "3"
platform: "linux"
package: "libtasn1"
version: "4.21.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/asn1_get_tag_der"
---

# asn1\_get\_tag\_der(3)

API function

## NAME

asn1\_get\_tag\_der - API function

## 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

- const unsigned char \* der

  DER data to decode.

- int der\_len

  Length of DER data to decode.

- unsigned char \* cls

  Output variable containing decoded class.

- int \* len

  Output variable containing the length of the DER TAG data.

- unsigned long \* tag

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

## DESCRIPTION

Decode the class and TAG from DER code.

## RETURNS

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

## 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

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/**