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

# [NAME](#NAME)

asn1\_get\_length\_der - API function

# [SYNOPSIS](#SYNOPSIS)

**#include <libtasn1.h>**

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

# [ARGUMENTS](#ARGUMENTS)

[const unsigned char * der](#const)

DER data to decode.

[int der\_len](#int)

Length of DER data to decode.

[int * len](#int~2)

Output variable containing the length of the DER length field.

# [DESCRIPTION](#DESCRIPTION)

Extract a length field from DER data.

# [RETURNS](#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)

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_length_der(3) from libtasn1 4.21.0-r6 (Chainguard OS)
Source: https://gitlab.com/gnutls/libtasn1