---
name: "asn1_get_length_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_length_der"
---

# asn1\_get\_length\_der(3)

API function

## NAME

asn1\_get\_length\_der - API function

## SYNOPSIS

**#include \<libtasn1.h\>**

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

## ARGUMENTS

- const unsigned char \* der

  DER data to decode.

- int der\_len

  Length of DER data to decode.

- int \* len

  Output variable containing the length of the DER length field.

## DESCRIPTION

Extract a length field from DER data.

## RETURNS

Return the decoded length value, or -1 on indefinite length, or -2 when the value was too big to fit in a int, or -4 when the decoded length value plus  *len* would exceed  *der\_len* .

## 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/**